diff --git a/setupTest.js b/setupTest.js
index c6223d215a..4d648782b3 100644
--- a/setupTest.js
+++ b/setupTest.js
@@ -1,3 +1,3 @@
 'use strict';
 
-jest.setTimeout(30000);
+jest.setTimeout(60000);
diff --git a/test/InvalidateCallback.test.js b/test/InvalidateCallback.test.js
deleted file mode 100644
index c95781f24e..0000000000
--- a/test/InvalidateCallback.test.js
+++ /dev/null
@@ -1,41 +0,0 @@
-'use strict';
-
-const webpack = require('webpack');
-const { noop } = require('webpack-dev-middleware/lib/util');
-const Server = require('../lib/Server');
-const config = require('./fixtures/simple-config/webpack.config');
-
-describe('Invalidate Callback', () => {
-  describe('Testing callback functions on calling invalidate without callback', () => {
-    it('should be `noop` (the default callback function)', (done) => {
-      const compiler = webpack(config);
-      const server = new Server(compiler);
-
-      server.invalidate();
-      expect(server.middleware.context.callbacks[0]).toBe(noop);
-
-      compiler.hooks.done.tap('webpack-dev-server', () => {
-        server.close(done);
-      });
-
-      compiler.run(() => {});
-    });
-  });
-
-  describe('Testing callback functions on calling invalidate with callback', () => {
-    it('should be `callback` function', (done) => {
-      const compiler = webpack(config);
-      const callback = jest.fn();
-      const server = new Server(compiler);
-      server.invalidate(callback);
-
-      expect(server.middleware.context.callbacks[0]).toBe(callback);
-
-      compiler.hooks.done.tap('webpack-dev-server', () => {
-        server.close(done);
-      });
-
-      compiler.run(() => {});
-    });
-  });
-});
diff --git a/test/MimeTypes.test.js b/test/MimeTypes.test.js
deleted file mode 100644
index dcf2f725e2..0000000000
--- a/test/MimeTypes.test.js
+++ /dev/null
@@ -1,58 +0,0 @@
-'use strict';
-
-const request = require('supertest');
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/simple-config/webpack.config');
-
-describe('MimeTypes configuration', () => {
-  afterEach(testServer.close);
-
-  it('remapping mime type without force should throw an error', () => {
-    expect(() => {
-      testServer.start(config, {
-        mimeTypes: { 'application/octet-stream': ['js'] },
-      });
-    }).toThrow(/Attempt to change mapping for/);
-  });
-
-  it('remapping mime type with force should not throw an error', (done) => {
-    testServer.start(
-      config,
-      {
-        mimeTypes: {
-          typeMap: { 'application/octet-stream': ['js'] },
-          force: true,
-        },
-      },
-      done
-    );
-  });
-});
-
-describe('custom mimeTypes', () => {
-  let server;
-  let req;
-
-  beforeAll((done) => {
-    server = testServer.start(
-      config,
-      {
-        mimeTypes: {
-          typeMap: { 'application/octet-stream': ['js'] },
-          force: true,
-        },
-      },
-      done
-    );
-    req = request(server.app);
-  });
-
-  afterAll(testServer.close);
-
-  it('request to bundle file with modified mime type', (done) => {
-    req
-      .get('/main.js')
-      .expect('Content-Type', /application\/octet-stream/)
-      .expect(200, done);
-  });
-});
diff --git a/test/Server.test.js b/test/Server.test.js
deleted file mode 100644
index 23acfaa9bf..0000000000
--- a/test/Server.test.js
+++ /dev/null
@@ -1,503 +0,0 @@
-'use strict';
-
-const { relative, sep } = require('path');
-const webpack = require('webpack');
-const request = require('supertest');
-// Mock opn before loading Server
-jest.mock('opn');
-// eslint-disable-next-line import/newline-after-import
-const opn = require('opn');
-opn.mockImplementation(() => {
-  return {
-    catch: jest.fn(),
-  };
-});
-jest.mock('sockjs/lib/transport');
-// eslint-disable-next-line import/newline-after-import
-const sockjs = require('sockjs/lib/transport');
-const Server = require('../lib/Server');
-const config = require('./fixtures/simple-config/webpack.config');
-const testServer = require('./helpers/test-server');
-
-describe('Server', () => {
-  describe('sockjs', () => {
-    it('add decorateConnection', () => {
-      expect(typeof sockjs.Session.prototype.decorateConnection).toEqual(
-        'function'
-      );
-    });
-  });
-
-  describe('addEntries', () => {
-    it('add hot option', (done) => {
-      const compiler = webpack(config);
-      const server = new Server(compiler, {
-        hot: true,
-      });
-
-      expect(
-        server.middleware.context.compiler.options.entry.map((p) => {
-          return relative('.', p).split(sep);
-        })
-      ).toMatchSnapshot();
-      expect(
-        server.middleware.context.compiler.options.plugins
-      ).toMatchSnapshot();
-
-      compiler.hooks.done.tap('webpack-dev-server', () => {
-        server.close(done);
-      });
-
-      compiler.run(() => {});
-    });
-
-    it('add hotOnly option', (done) => {
-      const compiler = webpack(config);
-      const server = new Server(compiler, {
-        hotOnly: true,
-      });
-
-      expect(
-        server.middleware.context.compiler.options.entry.map((p) => {
-          return relative('.', p).split(sep);
-        })
-      ).toMatchSnapshot();
-      expect(
-        server.middleware.context.compiler.options.plugins
-      ).toMatchSnapshot();
-
-      compiler.hooks.done.tap('webpack-dev-server', () => {
-        server.close(done);
-      });
-
-      compiler.run(() => {});
-    });
-  });
-
-  // issue: https://github.com/webpack/webpack-dev-server/issues/1724
-  describe('express.static.mine.types', () => {
-    beforeEach(() => {
-      jest.resetModules();
-    });
-
-    afterEach(() => {
-      jest.unmock('express');
-    });
-
-    it("should success even if mine.types doesn't exist", (done) => {
-      jest.mock('express', () => {
-        const data = jest.requireActual('express');
-        const { static: st } = data;
-        const { mime } = st;
-
-        delete mime.types;
-
-        expect(typeof mime.types).toEqual('undefined');
-
-        return Object.assign(data, {
-          static: Object.assign(st, {
-            mime,
-          }),
-        });
-      });
-
-      const compiler = webpack(config);
-      const server = new Server(compiler);
-
-      compiler.hooks.done.tap('webpack-dev-server', (s) => {
-        const output = server.getStats(s);
-        expect(output.errors.length).toEqual(0);
-
-        server.close(done);
-      });
-
-      compiler.run(() => {});
-      server.listen(8080, 'localhost');
-    });
-  });
-
-  describe('stats', () => {
-    it(`should works with difference stats values (contains 'hash', 'assets', 'warnings' and 'errors')`, () => {
-      const allStats = [
-        {},
-        // eslint-disable-next-line no-undefined
-        undefined,
-        false,
-        'errors-only',
-        {
-          assets: false,
-        },
-      ];
-
-      return allStats.reduce((p, stats) => {
-        return p.then(() => {
-          return new Promise((resolve) => {
-            const compiler = webpack(config);
-            const server = new Server(compiler, { stats });
-
-            compiler.hooks.done.tap('webpack-dev-server', (s) => {
-              expect(Object.keys(server.getStats(s))).toMatchSnapshot();
-
-              server.close(resolve);
-            });
-
-            compiler.run(() => {});
-            server.listen(8080, 'localhost');
-          });
-        });
-      }, Promise.resolve());
-    });
-
-    it('should respect warningsFilter', (done) => {
-      const compiler = webpack(config);
-      const server = new Server(compiler, {
-        stats: { warningsFilter: 'test' },
-      });
-
-      compiler.hooks.done.tap('webpack-dev-server', (s) => {
-        s.compilation.warnings = ['test', 'another warning'];
-
-        const output = server.getStats(s);
-
-        expect(output.warnings.length).toBe(1);
-        expect(output.warnings[0]).toBe('another warning');
-
-        server.close(done);
-      });
-
-      compiler.run(() => {});
-      server.listen(8080, 'localhost');
-    });
-
-    it('should open', (done) => {
-      const compiler = webpack(config);
-      const server = new Server(compiler, {
-        open: true,
-      });
-
-      compiler.hooks.done.tap('webpack-dev-server', () => {
-        expect(opn.mock.calls[0]).toEqual(['http://localhost:8080/', {}]);
-        expect(opn.mock.invocationCallOrder[0]).toEqual(1);
-        server.close(done);
-      });
-
-      compiler.run(() => {});
-      server.listen(8080, 'localhost');
-    });
-  });
-
-  describe('host', () => {
-    let server = null;
-    let req = null;
-
-    describe('is not be specified', () => {
-      beforeAll((done) => {
-        server = testServer.start(config, {}, done);
-        req = request(server.app);
-      });
-
-      it('server address', () => {
-        const address = server.listeningApp.address();
-
-        expect(address.address).toBe('127.0.0.1');
-        expect(address.port).toBe(8080);
-      });
-
-      it('Request to index', (done) => {
-        req.get('/').expect(200, done);
-      });
-
-      afterAll(testServer.close);
-    });
-
-    describe('is undefined', () => {
-      beforeAll((done) => {
-        server = testServer.start(
-          config,
-          {
-            // eslint-disable-next-line no-undefined
-            host: undefined,
-          },
-          done
-        );
-        req = request(server.app);
-      });
-
-      it('server address', () => {
-        const address = server.listeningApp.address();
-
-        expect(address.address).toBe('::');
-        expect(address.port).toBe(8080);
-      });
-
-      it('Request to index', (done) => {
-        req.get('/').expect(200, done);
-      });
-
-      afterAll(testServer.close);
-    });
-
-    describe('is null', () => {
-      beforeAll((done) => {
-        server = testServer.start(
-          config,
-          {
-            host: null,
-          },
-          done
-        );
-        req = request(server.app);
-      });
-
-      it('server address', () => {
-        const address = server.listeningApp.address();
-
-        expect(address.address).toBe('::');
-        expect(address.port).toBe(8080);
-      });
-
-      it('Request to index', (done) => {
-        req.get('/').expect(200, done);
-      });
-
-      afterAll(testServer.close);
-    });
-
-    describe('is 127.0.0.1 (IPv4)', () => {
-      beforeAll((done) => {
-        server = testServer.start(
-          config,
-          {
-            host: '127.0.0.1',
-          },
-          done
-        );
-        req = request(server.app);
-      });
-
-      it('server address', () => {
-        const address = server.listeningApp.address();
-
-        expect(address.address).toBe('127.0.0.1');
-        expect(address.port).toBe(8080);
-      });
-
-      it('Request to index', (done) => {
-        req.get('/').expect(200, done);
-      });
-
-      afterAll(testServer.close);
-    });
-
-    describe('is localhost', () => {
-      beforeAll((done) => {
-        server = testServer.start(
-          config,
-          {
-            host: 'localhost',
-          },
-          done
-        );
-        req = request(server.app);
-      });
-
-      it('server address', () => {
-        const address = server.listeningApp.address();
-
-        expect(address.address).toBe('127.0.0.1');
-        expect(address.port).toBe(8080);
-      });
-
-      it('Request to index', (done) => {
-        req.get('/').expect(200, done);
-      });
-
-      afterAll(testServer.close);
-    });
-
-    describe('is 0.0.0.0', () => {
-      beforeAll((done) => {
-        server = testServer.start(
-          config,
-          {
-            host: '0.0.0.0',
-          },
-          done
-        );
-        req = request(server.app);
-      });
-
-      it('server address', () => {
-        const address = server.listeningApp.address();
-
-        expect(address.address).toBe('0.0.0.0');
-        expect(address.port).toBe(8080);
-      });
-
-      it('Request to index', (done) => {
-        req.get('/').expect(200, done);
-      });
-
-      afterAll(testServer.close);
-    });
-  });
-
-  describe('port', () => {
-    let server = null;
-    let req = null;
-
-    describe('is not be specified', () => {
-      beforeAll((done) => {
-        server = testServer.start(config, {}, done);
-        req = request(server.app);
-      });
-
-      it('server address', () => {
-        const address = server.listeningApp.address();
-
-        expect(address.address).toBe('127.0.0.1');
-        // Random port
-        expect(address.port).toBeDefined();
-      });
-
-      it('Request to index', (done) => {
-        req.get('/').expect(200, done);
-      });
-
-      afterAll(testServer.close);
-    });
-
-    describe('is undefined', () => {
-      beforeAll((done) => {
-        server = testServer.start(
-          config,
-          {
-            // eslint-disable-next-line no-undefined
-            port: undefined,
-          },
-          done
-        );
-        req = request(server.app);
-      });
-
-      it('server address', () => {
-        const address = server.listeningApp.address();
-
-        expect(address.address).toBe('127.0.0.1');
-        // Random port
-        expect(address.port).toBeDefined();
-      });
-
-      it('Request to index', (done) => {
-        req.get('/').expect(200, done);
-      });
-
-      afterAll(testServer.close);
-    });
-
-    describe('is null', () => {
-      beforeAll((done) => {
-        server = testServer.start(
-          config,
-          {
-            port: null,
-          },
-          done
-        );
-        req = request(server.app);
-      });
-
-      it('server address', () => {
-        const address = server.listeningApp.address();
-
-        expect(address.address).toBe('127.0.0.1');
-        // Random port
-        expect(address.port).toBeDefined();
-      });
-
-      it('Request to index', (done) => {
-        req.get('/').expect(200, done);
-      });
-
-      afterAll(testServer.close);
-    });
-
-    describe('is "33333"', () => {
-      beforeAll((done) => {
-        server = testServer.start(
-          config,
-          {
-            port: '33333',
-          },
-          done
-        );
-        req = request(server.app);
-      });
-
-      it('server address', () => {
-        const address = server.listeningApp.address();
-
-        expect(address.address).toBe('127.0.0.1');
-        expect(address.port).toBe(33333);
-      });
-
-      it('Request to index', (done) => {
-        req.get('/').expect(200, done);
-      });
-
-      afterAll(testServer.close);
-    });
-
-    describe('is 33333', () => {
-      beforeAll((done) => {
-        server = testServer.start(
-          config,
-          {
-            port: '33333',
-          },
-          done
-        );
-        req = request(server.app);
-      });
-
-      it('server address', () => {
-        const address = server.listeningApp.address();
-
-        expect(address.address).toBe('127.0.0.1');
-        expect(address.port).toBe(33333);
-      });
-
-      it('Request to index', (done) => {
-        req.get('/').expect(200, done);
-      });
-
-      afterAll(testServer.close);
-    });
-  });
-
-  describe('WEBPACK_DEV_SERVER environment variable', () => {
-    const OLD_ENV = process.env;
-
-    beforeEach(() => {
-      // this is important - it clears the cache
-      jest.resetModules();
-
-      process.env = { ...OLD_ENV };
-
-      delete process.env.WEBPACK_DEV_SERVER;
-    });
-
-    afterEach(() => {
-      process.env = OLD_ENV;
-    });
-
-    it('should be present', () => {
-      expect(process.env.WEBPACK_DEV_SERVER).toBeUndefined();
-
-      // eslint-disable-next-line global-require
-      require('../lib/Server');
-
-      expect(process.env.WEBPACK_DEV_SERVER).toBe(true);
-    });
-  });
-});
diff --git a/test/__snapshots__/Server.test.js.snap b/test/__snapshots__/Server.test.js.snap
deleted file mode 100644
index afd2139df5..0000000000
--- a/test/__snapshots__/Server.test.js.snap
+++ /dev/null
@@ -1,116 +0,0 @@
-// Jest Snapshot v1, https://goo.gl/fbAQLP
-
-exports[`Server addEntries add hot option 1`] = `
-Array [
-  Array [
-    "client",
-    "index.js?http:",
-    "localhost",
-  ],
-  Array [
-    "node_modules",
-    "webpack",
-    "hot",
-    "dev-server.js",
-  ],
-  Array [
-    "foo.js",
-  ],
-]
-`;
-
-exports[`Server addEntries add hot option 2`] = `
-Array [
-  HotModuleReplacementPlugin {
-    "fullBuildTimeout": 200,
-    "multiStep": undefined,
-    "options": Object {},
-    "requestTimeout": 10000,
-  },
-]
-`;
-
-exports[`Server addEntries add hotOnly option 1`] = `
-Array [
-  Array [
-    "client",
-    "index.js?http:",
-    "localhost",
-  ],
-  Array [
-    "node_modules",
-    "webpack",
-    "hot",
-    "only-dev-server.js",
-  ],
-  Array [
-    "foo.js",
-  ],
-]
-`;
-
-exports[`Server addEntries add hotOnly option 2`] = `
-Array [
-  HotModuleReplacementPlugin {
-    "fullBuildTimeout": 200,
-    "multiStep": undefined,
-    "options": Object {},
-    "requestTimeout": 10000,
-  },
-]
-`;
-
-exports[`Server stats should works with difference stats values (contains 'hash', 'assets', 'warnings' and 'errors') 1`] = `
-Array [
-  "errors",
-  "warnings",
-  "hash",
-  "assetsByChunkName",
-  "assets",
-  "filteredAssets",
-]
-`;
-
-exports[`Server stats should works with difference stats values (contains 'hash', 'assets', 'warnings' and 'errors') 2`] = `
-Array [
-  "errors",
-  "warnings",
-  "hash",
-  "assetsByChunkName",
-  "assets",
-  "filteredAssets",
-]
-`;
-
-exports[`Server stats should works with difference stats values (contains 'hash', 'assets', 'warnings' and 'errors') 3`] = `
-Array [
-  "errors",
-  "warnings",
-  "hash",
-  "assetsByChunkName",
-  "assets",
-  "filteredAssets",
-]
-`;
-
-exports[`Server stats should works with difference stats values (contains 'hash', 'assets', 'warnings' and 'errors') 4`] = `
-Array [
-  "errors",
-  "warnings",
-  "hash",
-  "assetsByChunkName",
-  "assets",
-  "filteredAssets",
-]
-`;
-
-exports[`Server stats should works with difference stats values (contains 'hash', 'assets', 'warnings' and 'errors') 5`] = `
-Array [
-  "errors",
-  "warnings",
-  "hash",
-  "assetsByChunkName",
-  "assets",
-  "filteredAssets",
-]
-`;
diff --git a/test/cli.test.js b/test/cli/cli.test.js
similarity index 84%
rename from test/cli.test.js
rename to test/cli/cli.test.js
index d9b7b72b41..0a009c3503 100644
--- a/test/cli.test.js
+++ b/test/cli/cli.test.js
@@ -1,18 +1,18 @@
 'use strict';
 
-/* eslint-disable
-  array-bracket-spacing,
-*/
 const { unlink } = require('fs');
 const { join, resolve } = require('path');
 const execa = require('execa');
-const testBin = require('./helpers/test-bin');
+const testBin = require('../helpers/test-bin');
 
-const httpsCertificateDirectory = join(__dirname, 'fixtures/https-certificate');
-const caPath = join(httpsCertificateDirectory, 'ca.pem');
-const pfxPath = join(httpsCertificateDirectory, 'server.pfx');
-const keyPath = join(httpsCertificateDirectory, 'server.key');
-const certPath = join(httpsCertificateDirectory, 'server.crt');
+const httpsCertificateDirectory = resolve(
+  __dirname,
+  '../fixtures/https-certificate'
+);
+const caPath = resolve(httpsCertificateDirectory, 'ca.pem');
+const pfxPath = resolve(httpsCertificateDirectory, 'server.pfx');
+const keyPath = resolve(httpsCertificateDirectory, 'server.key');
+const certPath = resolve(httpsCertificateDirectory, 'server.crt');
 
 describe('CLI', () => {
   it('--progress', (done) => {
@@ -92,6 +92,7 @@ describe('CLI', () => {
           done();
         } else {
           expect(output.stdout.includes(socketPath)).toBe(true);
+
           unlink(socketPath, () => {
             done();
           });
@@ -103,7 +104,7 @@ describe('CLI', () => {
   it('should accept the promise function of webpack.config.js', (done) => {
     testBin(
       false,
-      resolve(__dirname, 'fixtures/promise-config/webpack.config.js')
+      resolve(__dirname, '../fixtures/promise-config/webpack.config.js')
     )
       .then((output) => {
         expect(output.code).toEqual(0);
@@ -117,14 +118,16 @@ describe('CLI', () => {
   });
 
   it('should exit the process when SIGINT is detected', (done) => {
-    const cliPath = resolve(__dirname, '../bin/webpack-dev-server.js');
-    const examplePath = resolve(__dirname, '../examples/cli/public');
+    const cliPath = resolve(__dirname, '../../bin/webpack-dev-server.js');
+    const examplePath = resolve(__dirname, '../../examples/cli/public');
     const cp = execa('node', [cliPath], { cwd: examplePath });
 
     cp.stdout.on('data', (data) => {
       const bits = data.toString();
+
       if (/Compiled successfully/.test(bits)) {
         expect(cp.pid !== 0).toBe(true);
+
         cp.kill('SIGINT');
       }
     });
@@ -135,16 +138,18 @@ describe('CLI', () => {
   });
 
   it('should exit the process when SIGINT is detected, even before the compilation is done', (done) => {
-    const cliPath = resolve(__dirname, '../bin/webpack-dev-server.js');
-    const examplePath = resolve(__dirname, '../examples/cli/public');
+    const cliPath = resolve(__dirname, '../../bin/webpack-dev-server.js');
+    const examplePath = resolve(__dirname, '../../examples/cli/public');
     const cp = execa('node', [cliPath], { cwd: examplePath });
     let killed = false;
 
     cp.stdout.on('data', () => {
       if (!killed) {
         expect(cp.pid !== 0).toBe(true);
+
         cp.kill('SIGINT');
       }
+
       killed = true;
     });
 
@@ -154,8 +159,8 @@ describe('CLI', () => {
   });
 
   it('should use different random port when multiple instances are started on different processes', (done) => {
-    const cliPath = resolve(__dirname, '../bin/webpack-dev-server.js');
-    const examplePath = resolve(__dirname, '../examples/cli/public');
+    const cliPath = resolve(__dirname, '../../bin/webpack-dev-server.js');
+    const examplePath = resolve(__dirname, '../../examples/cli/public');
 
     const cp = execa('node', [cliPath], { cwd: examplePath });
     const cp2 = execa('node', [cliPath], { cwd: examplePath });
diff --git a/test/client/default/__snapshots__/index.test.js.snap b/test/client/__snapshots__/index.test.js.snap
similarity index 100%
rename from test/client/default/__snapshots__/index.test.js.snap
rename to test/client/__snapshots__/index.test.js.snap
diff --git a/test/SockJSClient.test.js b/test/client/clients/SockJSClient.test.js
similarity index 90%
rename from test/SockJSClient.test.js
rename to test/client/clients/SockJSClient.test.js
index b6fbed8ac3..ceb6fdc26e 100644
--- a/test/SockJSClient.test.js
+++ b/test/client/clients/SockJSClient.test.js
@@ -3,7 +3,7 @@
 const http = require('http');
 const express = require('express');
 const sockjs = require('sockjs');
-const SockJSClient = require('../client-src/clients/SockJSClient');
+const SockJSClient = require('../../../client-src/clients/SockJSClient');
 
 describe('SockJSClient', () => {
   let socketServer;
@@ -12,6 +12,7 @@ describe('SockJSClient', () => {
   beforeAll((done) => {
     // eslint-disable-next-line new-cap
     const app = new express();
+
     listeningApp = http.createServer(app);
     listeningApp.listen(8080, 'localhost', () => {
       socketServer = sockjs.createServer();
@@ -23,15 +24,18 @@ describe('SockJSClient', () => {
   });
 
   describe('client', () => {
-    it('should open, recieve message, and close', (done) => {
+    it('should open, receive message, and close', (done) => {
       socketServer.on('connection', (connection) => {
         connection.write('hello world');
+
         setTimeout(() => {
           connection.close();
         }, 1000);
       });
+
       const client = new SockJSClient('http://localhost:8080/sockjs-node');
       const data = [];
+
       client.onOpen(() => {
         data.push('open');
       });
@@ -41,6 +45,7 @@ describe('SockJSClient', () => {
       client.onMessage((msg) => {
         data.push(msg);
       });
+
       setTimeout(() => {
         expect(data.length).toEqual(3);
         expect(data[0]).toEqual('open');
diff --git a/test/client/default/index.test.js b/test/client/index.test.js
similarity index 87%
rename from test/client/default/index.test.js
rename to test/client/index.test.js
index 935ecb04be..053ee295bc 100644
--- a/test/client/default/index.test.js
+++ b/test/client/index.test.js
@@ -21,41 +21,41 @@ describe('index', () => {
     self.location.reload = jest.fn();
 
     // log
-    jest.setMock('../../../client-src/default/utils/log.js', {
+    jest.setMock('../../client-src/default/utils/log.js', {
       log: {
         info: jest.fn(),
         warn: jest.fn(),
         error: jest.fn(),
       },
     });
-    log = require('../../../client-src/default/utils/log');
+    log = require('../../client-src/default/utils/log');
 
     // socket
-    jest.setMock('../../../client-src/default/socket.js', jest.fn());
-    socket = require('../../../client-src/default/socket');
+    jest.setMock('../../client-src/default/socket.js', jest.fn());
+    socket = require('../../client-src/default/socket');
 
     // overlay
-    jest.setMock('../../../client-src/default/overlay.js', {
+    jest.setMock('../../client-src/default/overlay.js', {
       clear: jest.fn(),
       showMessage: jest.fn(),
     });
-    overlay = require('../../../client-src/default/overlay');
+    overlay = require('../../client-src/default/overlay');
 
     // reloadApp
-    jest.setMock('../../../client-src/default/utils/reloadApp.js', jest.fn());
-    reloadApp = require('../../../client-src/default/utils/reloadApp');
+    jest.setMock('../../client-src/default/utils/reloadApp.js', jest.fn());
+    reloadApp = require('../../client-src/default/utils/reloadApp');
 
     // sendMessage
-    jest.setMock('../../../client-src/default/utils/sendMessage.js', jest.fn());
-    sendMessage = require('../../../client-src/default/utils/sendMessage');
+    jest.setMock('../../client-src/default/utils/sendMessage.js', jest.fn());
+    sendMessage = require('../../client-src/default/utils/sendMessage');
 
     // createSocketUrl
     jest.setMock(
-      '../../../client-src/default/utils/createSocketUrl.js',
+      '../../client-src/default/utils/createSocketUrl.js',
       () => 'mock-url'
     );
 
-    require('../../../client-src/default');
+    require('../../client-src/default');
     onSocketMessage = socket.mock.calls[0][1];
   });
 
diff --git a/test/client/default/utils/__snapshots__/createSocketUrl.test.js.snap b/test/client/utils/__snapshots__/createSocketUrl.test.js.snap
similarity index 100%
rename from test/client/default/utils/__snapshots__/createSocketUrl.test.js.snap
rename to test/client/utils/__snapshots__/createSocketUrl.test.js.snap
diff --git a/test/client/default/utils/__snapshots__/getCurrentScriptSource.test.js.snap b/test/client/utils/__snapshots__/getCurrentScriptSource.test.js.snap
similarity index 100%
rename from test/client/default/utils/__snapshots__/getCurrentScriptSource.test.js.snap
rename to test/client/utils/__snapshots__/getCurrentScriptSource.test.js.snap
diff --git a/test/client/default/utils/__snapshots__/log.test.js.snap b/test/client/utils/__snapshots__/log.test.js.snap
similarity index 100%
rename from test/client/default/utils/__snapshots__/log.test.js.snap
rename to test/client/utils/__snapshots__/log.test.js.snap
diff --git a/test/client/default/utils/__snapshots__/reloadApp.test.js.snap b/test/client/utils/__snapshots__/reloadApp.test.js.snap
similarity index 100%
rename from test/client/default/utils/__snapshots__/reloadApp.test.js.snap
rename to test/client/utils/__snapshots__/reloadApp.test.js.snap
diff --git a/test/client/default/utils/__snapshots__/sendMessage.test.js.snap b/test/client/utils/__snapshots__/sendMessage.test.js.snap
similarity index 100%
rename from test/client/default/utils/__snapshots__/sendMessage.test.js.snap
rename to test/client/utils/__snapshots__/sendMessage.test.js.snap
diff --git a/test/client/default/utils/createSocketUrl.test.js b/test/client/utils/createSocketUrl.test.js
similarity index 85%
rename from test/client/default/utils/createSocketUrl.test.js
rename to test/client/utils/createSocketUrl.test.js
index cd2aab7f66..892e8204eb 100644
--- a/test/client/default/utils/createSocketUrl.test.js
+++ b/test/client/utils/createSocketUrl.test.js
@@ -17,12 +17,12 @@ describe('createSocketUrl', () => {
 
   samples.forEach((url) => {
     jest.doMock(
-      '../../../../client-src/default/utils/getCurrentScriptSource.js',
+      '../../../client-src/default/utils/getCurrentScriptSource.js',
       () => () => url
     );
 
     // eslint-disable-next-line global-require
-    const createSocketUrl = require('../../../../client-src/default/utils/createSocketUrl');
+    const createSocketUrl = require('../../../client-src/default/utils/createSocketUrl');
 
     test(`should return the url when __resourceQuery is ${url}`, () => {
       expect(createSocketUrl(url)).toMatchSnapshot();
diff --git a/test/client/default/utils/getCurrentScriptSource.test.js b/test/client/utils/getCurrentScriptSource.test.js
similarity index 91%
rename from test/client/default/utils/getCurrentScriptSource.test.js
rename to test/client/utils/getCurrentScriptSource.test.js
index a7cf0777d6..8fb953b1f3 100644
--- a/test/client/default/utils/getCurrentScriptSource.test.js
+++ b/test/client/utils/getCurrentScriptSource.test.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const getCurrentScriptSource = require('../../../../client-src/default/utils/getCurrentScriptSource');
+const getCurrentScriptSource = require('../../../client-src/default/utils/getCurrentScriptSource');
 
 describe('getCurrentScriptSource', () => {
   afterEach(() => {
diff --git a/test/client/default/utils/log.test.js b/test/client/utils/log.test.js
similarity index 94%
rename from test/client/default/utils/log.test.js
rename to test/client/utils/log.test.js
index b18f8d815c..79021d13d7 100644
--- a/test/client/default/utils/log.test.js
+++ b/test/client/utils/log.test.js
@@ -18,8 +18,7 @@ describe('log', () => {
     });
 
     // eslint-disable-next-line global-require
-    setLogLevel = require('../../../../client-src/default/utils/log')
-      .setLogLevel;
+    setLogLevel = require('../../../client-src/default/utils/log').setLogLevel;
   });
 
   afterEach(() => {
diff --git a/test/client/default/utils/reloadApp.test.js b/test/client/utils/reloadApp.test.js
similarity index 97%
rename from test/client/default/utils/reloadApp.test.js
rename to test/client/utils/reloadApp.test.js
index d4c4261929..13a392b117 100644
--- a/test/client/default/utils/reloadApp.test.js
+++ b/test/client/utils/reloadApp.test.js
@@ -9,10 +9,12 @@ describe('reloadApp', () => {
 
   beforeEach(() => {
     locationValue = self.location;
+
     self.postMessage = jest.fn();
     self.location.reload = jest.fn();
 
     jest.mock('loglevel');
+
     // eslint-disable-next-line global-require
     log = require('loglevel');
     log.getLogger.mockImplementation(() => {
@@ -23,7 +25,7 @@ describe('reloadApp', () => {
     });
 
     // eslint-disable-next-line global-require
-    reloadApp = require('../../../../client-src/default/utils/reloadApp');
+    reloadApp = require('../../../client-src/default/utils/reloadApp');
   });
 
   afterEach(() => {
diff --git a/test/client/default/utils/sendMessage.test.js b/test/client/utils/sendMessage.test.js
similarity index 81%
rename from test/client/default/utils/sendMessage.test.js
rename to test/client/utils/sendMessage.test.js
index 11e176175f..a60f2548bc 100644
--- a/test/client/default/utils/sendMessage.test.js
+++ b/test/client/utils/sendMessage.test.js
@@ -2,7 +2,7 @@
 
 /* global self */
 
-const sendMessage = require('../../../../client-src/default/utils/sendMessage');
+const sendMessage = require('../../../client-src/default/utils/sendMessage');
 
 describe('sendMessage', () => {
   afterEach(() => {
@@ -11,7 +11,9 @@ describe('sendMessage', () => {
 
   test('should run self.postMessage', () => {
     self.postMessage = jest.fn();
+
     sendMessage('foo', 'bar');
+
     expect(self.postMessage).toBeCalled();
     expect(self.postMessage.mock.calls[0]).toMatchSnapshot();
   });
diff --git a/test/MultiCompiler.test.js b/test/integration/MultiCompiler.test.js
similarity index 66%
rename from test/MultiCompiler.test.js
rename to test/integration/MultiCompiler.test.js
index a59fa2df77..2b203a7065 100644
--- a/test/MultiCompiler.test.js
+++ b/test/integration/MultiCompiler.test.js
@@ -1,12 +1,13 @@
 'use strict';
 
 const request = require('supertest');
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/multi-compiler-config/webpack.config');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/multi-compiler-config/webpack.config');
 
-describe('MultiCompiler', () => {
+describe('multi compiler', () => {
   let server;
   let req;
+
   beforeAll((done) => {
     server = testServer.start(config, {}, done);
     req = request(server.app);
@@ -15,7 +16,7 @@ describe('MultiCompiler', () => {
   afterAll(testServer.close);
 
   // TODO: this is a very basic test, optimally it should test multiple configs etc.
-  it('GET request to bundle', (done) => {
+  it('should handle GET request to bundle', (done) => {
     req
       .get('/main.js')
       .expect('Content-Type', 'application/javascript; charset=UTF-8')
diff --git a/test/UniversalCompiler.test.js b/test/integration/UniversalCompiler.test.js
similarity index 87%
rename from test/UniversalCompiler.test.js
rename to test/integration/UniversalCompiler.test.js
index 2588a47391..1eaec5ed70 100644
--- a/test/UniversalCompiler.test.js
+++ b/test/integration/UniversalCompiler.test.js
@@ -1,12 +1,13 @@
 'use strict';
 
 const request = require('supertest');
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/universal-compiler-config/webpack.config');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/universal-compiler-config/webpack.config');
 
-describe('UniversalCompiler', () => {
+describe('universal compiler', () => {
   let server;
   let req;
+
   beforeAll((done) => {
     server = testServer.start(config, { inline: true }, done);
     req = request(server.app);
diff --git a/test/server/Server.test.js b/test/server/Server.test.js
new file mode 100644
index 0000000000..b2b44731e2
--- /dev/null
+++ b/test/server/Server.test.js
@@ -0,0 +1,170 @@
+'use strict';
+
+const { relative, sep } = require('path');
+const webpack = require('webpack');
+const sockjs = require('sockjs/lib/transport');
+const { noop } = require('webpack-dev-middleware/lib/util');
+const Server = require('../../lib/Server');
+const config = require('../fixtures/simple-config/webpack.config');
+
+jest.mock('sockjs/lib/transport');
+
+describe('Server', () => {
+  describe('sockjs', () => {
+    it('add decorateConnection', () => {
+      expect(typeof sockjs.Session.prototype.decorateConnection).toEqual(
+        'function'
+      );
+    });
+  });
+
+  describe('addEntries', () => {
+    it('add hot option', (done) => {
+      const compiler = webpack(config);
+      const server = new Server(compiler, {
+        hot: true,
+      });
+
+      expect(
+        server.middleware.context.compiler.options.entry.map((p) => {
+          return relative('.', p).split(sep);
+        })
+      ).toMatchSnapshot();
+      expect(
+        server.middleware.context.compiler.options.plugins
+      ).toMatchSnapshot();
+
+      compiler.hooks.done.tap('webpack-dev-server', () => {
+        server.close(done);
+      });
+
+      compiler.run(() => {});
+    });
+
+    it('add hotOnly option', (done) => {
+      const compiler = webpack(config);
+      const server = new Server(compiler, {
+        hotOnly: true,
+      });
+
+      expect(
+        server.middleware.context.compiler.options.entry.map((p) => {
+          return relative('.', p).split(sep);
+        })
+      ).toMatchSnapshot();
+      expect(
+        server.middleware.context.compiler.options.plugins
+      ).toMatchSnapshot();
+
+      compiler.hooks.done.tap('webpack-dev-server', () => {
+        server.close(done);
+      });
+
+      compiler.run(() => {});
+    });
+  });
+
+  // issue: https://github.com/webpack/webpack-dev-server/issues/1724
+  describe('express.static.mine.types', () => {
+    beforeEach(() => {
+      jest.resetModules();
+    });
+
+    afterEach(() => {
+      jest.unmock('express');
+    });
+
+    it("should success even if mine.types doesn't exist", (done) => {
+      jest.mock('express', () => {
+        const data = jest.requireActual('express');
+        const { static: st } = data;
+        const { mime } = st;
+
+        delete mime.types;
+
+        expect(typeof mime.types).toEqual('undefined');
+
+        return Object.assign(data, {
+          static: Object.assign(st, {
+            mime,
+          }),
+        });
+      });
+
+      const compiler = webpack(config);
+      const server = new Server(compiler);
+
+      compiler.hooks.done.tap('webpack-dev-server', (s) => {
+        const output = server.getStats(s);
+        expect(output.errors.length).toEqual(0);
+
+        server.close(done);
+      });
+
+      compiler.run(() => {});
+      server.listen(8080, 'localhost');
+    });
+  });
+
+  describe('WEBPACK_DEV_SERVER environment variable', () => {
+    const OLD_ENV = process.env;
+
+    beforeEach(() => {
+      // this is important - it clears the cache
+      jest.resetModules();
+
+      process.env = { ...OLD_ENV };
+
+      delete process.env.WEBPACK_DEV_SERVER;
+    });
+
+    afterEach(() => {
+      process.env = OLD_ENV;
+    });
+
+    it('should be present', () => {
+      expect(process.env.WEBPACK_DEV_SERVER).toBeUndefined();
+
+      // eslint-disable-next-line global-require
+      require('../../lib/Server');
+
+      expect(process.env.WEBPACK_DEV_SERVER).toBe(true);
+    });
+  });
+
+  describe('Invalidate Callback', () => {
+    describe('Testing callback functions on calling invalidate without callback', () => {
+      it('should be `noop` (the default callback function)', (done) => {
+        const compiler = webpack(config);
+        const server = new Server(compiler);
+
+        server.invalidate();
+        expect(server.middleware.context.callbacks[0]).toBe(noop);
+
+        compiler.hooks.done.tap('webpack-dev-server', () => {
+          server.close(done);
+        });
+
+        compiler.run(() => {});
+      });
+    });
+
+    describe('Testing callback functions on calling invalidate with callback', () => {
+      it('should be `callback` function', (done) => {
+        const compiler = webpack(config);
+        const callback = jest.fn();
+        const server = new Server(compiler);
+
+        server.invalidate(callback);
+
+        expect(server.middleware.context.callbacks[0]).toBe(callback);
+
+        compiler.hooks.done.tap('webpack-dev-server', () => {
+          server.close(done);
+        });
+
+        compiler.run(() => {});
+      });
+    });
+  });
+});
diff --git a/test/server/__snapshots__/Server.test.js.snap b/test/server/__snapshots__/Server.test.js.snap
new file mode 100644
index 0000000000..b606b0561f
--- /dev/null
+++ b/test/server/__snapshots__/Server.test.js.snap
@@ -0,0 +1,61 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Server addEntries add hot option 1`] = `
+Array [
+  Array [
+    "client",
+    "index.js?http:",
+    "localhost",
+  ],
+  Array [
+    "node_modules",
+    "webpack",
+    "hot",
+    "dev-server.js",
+  ],
+  Array [
+    "foo.js",
+  ],
+]
+`;
+
+exports[`Server addEntries add hot option 2`] = `
+Array [
+  HotModuleReplacementPlugin {
+    "fullBuildTimeout": 200,
+    "multiStep": undefined,
+    "options": Object {},
+    "requestTimeout": 10000,
+  },
+]
+`;
+
+exports[`Server addEntries add hotOnly option 1`] = `
+Array [
+  Array [
+    "client",
+    "index.js?http:",
+    "localhost",
+  ],
+  Array [
+    "node_modules",
+    "webpack",
+    "hot",
+    "only-dev-server.js",
+  ],
+  Array [
+    "foo.js",
+  ],
+]
+`;
+
+exports[`Server addEntries add hotOnly option 2`] = `
+Array [
+  HotModuleReplacementPlugin {
+    "fullBuildTimeout": 200,
+    "multiStep": undefined,
+    "options": Object {},
+    "requestTimeout": 10000,
+  },
+]
+`;
diff --git a/test/server/__snapshots__/stats-option.test.js.snap b/test/server/__snapshots__/stats-option.test.js.snap
new file mode 100644
index 0000000000..b5405f897e
--- /dev/null
+++ b/test/server/__snapshots__/stats-option.test.js.snap
@@ -0,0 +1,56 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`stats option should works with difference stats values (contains 'hash', 'assets', 'warnings' and 'errors') 1`] = `
+Array [
+  "errors",
+  "warnings",
+  "hash",
+  "assetsByChunkName",
+  "assets",
+  "filteredAssets",
+]
+`;
+
+exports[`stats option should works with difference stats values (contains 'hash', 'assets', 'warnings' and 'errors') 2`] = `
+Array [
+  "errors",
+  "warnings",
+  "hash",
+  "assetsByChunkName",
+  "assets",
+  "filteredAssets",
+]
+`;
+
+exports[`stats option should works with difference stats values (contains 'hash', 'assets', 'warnings' and 'errors') 3`] = `
+Array [
+  "errors",
+  "warnings",
+  "hash",
+  "assetsByChunkName",
+  "assets",
+  "filteredAssets",
+]
+`;
+
+exports[`stats option should works with difference stats values (contains 'hash', 'assets', 'warnings' and 'errors') 4`] = `
+Array [
+  "errors",
+  "warnings",
+  "hash",
+  "assetsByChunkName",
+  "assets",
+  "filteredAssets",
+]
+`;
+
+exports[`stats option should works with difference stats values (contains 'hash', 'assets', 'warnings' and 'errors') 5`] = `
+Array [
+  "errors",
+  "warnings",
+  "hash",
+  "assetsByChunkName",
+  "assets",
+  "filteredAssets",
+]
+`;
diff --git a/test/server/after-option.test.js b/test/server/after-option.test.js
new file mode 100644
index 0000000000..69f0b48f1a
--- /dev/null
+++ b/test/server/after-option.test.js
@@ -0,0 +1,49 @@
+'use strict';
+
+const request = require('supertest');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/simple-config/webpack.config');
+
+describe('after option', () => {
+  let server;
+  let req;
+
+  beforeAll((done) => {
+    server = testServer.start(
+      config,
+      {
+        after: (appArg, serverArg, compilerArg) => {
+          if (!appArg) {
+            throw new Error('app is not defined');
+          }
+
+          if (!serverArg) {
+            throw new Error('server is not defined');
+          }
+
+          if (!compilerArg) {
+            throw new Error('compiler is not defined');
+          }
+
+          appArg.get('/after/some/path', (_, response) => {
+            response.send('after');
+          });
+        },
+      },
+      done
+    );
+    req = request(server.app);
+  });
+
+  afterAll(testServer.close);
+
+  it('should handle after route', () => {
+    return req
+      .get('/after/some/path')
+      .expect('Content-Type', 'text/html; charset=utf-8')
+      .expect(200)
+      .then((response) => {
+        expect(response.text).toBe('after');
+      });
+  });
+});
diff --git a/test/BeforeAndAfter.test.js b/test/server/before-option.test.js
similarity index 52%
rename from test/BeforeAndAfter.test.js
rename to test/server/before-option.test.js
index c6e4a5b817..0966d28e18 100644
--- a/test/BeforeAndAfter.test.js
+++ b/test/server/before-option.test.js
@@ -1,10 +1,10 @@
 'use strict';
 
 const request = require('supertest');
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/simple-config/webpack.config');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/simple-config/webpack.config');
 
-describe('Before And After options', () => {
+describe('before option', () => {
   let server;
   let req;
 
@@ -29,23 +29,6 @@ describe('Before And After options', () => {
             response.send('before');
           });
         },
-        after: (appArg, serverArg, compilerArg) => {
-          if (!appArg) {
-            throw new Error('app is not defined');
-          }
-
-          if (!serverArg) {
-            throw new Error('server is not defined');
-          }
-
-          if (!compilerArg) {
-            throw new Error('compiler is not defined');
-          }
-
-          appArg.get('/after/some/path', (_, response) => {
-            response.send('after');
-          });
-        },
       },
       done
     );
@@ -63,14 +46,4 @@ describe('Before And After options', () => {
         expect(response.text).toBe('before');
       });
   });
-
-  it('should handle after route', () => {
-    return req
-      .get('/after/some/path')
-      .expect('Content-Type', 'text/html; charset=utf-8')
-      .expect(200)
-      .then((response) => {
-        expect(response.text).toBe('after');
-      });
-  });
 });
diff --git a/test/Compress.test.js b/test/server/compress-option.test.js
similarity index 86%
rename from test/Compress.test.js
rename to test/server/compress-option.test.js
index 4329cecb37..451639fa79 100644
--- a/test/Compress.test.js
+++ b/test/server/compress-option.test.js
@@ -6,14 +6,14 @@
 'use strict';
 
 const request = require('supertest');
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/simple-config-other/webpack.config');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/simple-config-other/webpack.config');
 
-describe('Compress', () => {
+describe('compress option', () => {
   let server;
   let req;
 
-  describe('undefined', () => {
+  describe('not specify', () => {
     beforeAll((done) => {
       server = testServer.start(config, {}, done);
       req = request(server.app);
@@ -33,7 +33,7 @@ describe('Compress', () => {
     });
   });
 
-  describe('true', () => {
+  describe('as a true', () => {
     beforeAll((done) => {
       server = testServer.start(
         config,
@@ -55,7 +55,7 @@ describe('Compress', () => {
     });
   });
 
-  describe('false', () => {
+  describe('as a false', () => {
     beforeAll((done) => {
       server = testServer.start(
         config,
diff --git a/test/ContentBase.test.js b/test/server/contentBase-option.test.js
similarity index 94%
rename from test/ContentBase.test.js
rename to test/server/contentBase-option.test.js
index 24311dc396..9187c16e77 100644
--- a/test/ContentBase.test.js
+++ b/test/server/contentBase-option.test.js
@@ -3,24 +3,24 @@
 const path = require('path');
 const fs = require('fs');
 const request = require('supertest');
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/contentbase-config/webpack.config');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/contentbase-config/webpack.config');
 
-const contentBasePublic = path.join(
+const contentBasePublic = path.resolve(
   __dirname,
-  'fixtures/contentbase-config/public'
+  '../fixtures/contentbase-config/public'
 );
-const contentBaseOther = path.join(
+const contentBaseOther = path.resolve(
   __dirname,
-  'fixtures/contentbase-config/other'
+  '../fixtures/contentbase-config/other'
 );
 
-describe('ContentBase', () => {
+describe('contentBase option', () => {
   let server;
   let req;
 
   describe('to directory', () => {
-    const nestedFile = path.join(contentBasePublic, 'assets/example.txt');
+    const nestedFile = path.resolve(contentBasePublic, 'assets/example.txt');
 
     beforeAll((done) => {
       server = testServer.start(
@@ -38,6 +38,7 @@ describe('ContentBase', () => {
       testServer.close(() => {
         done();
       });
+
       fs.truncateSync(nestedFile);
     });
 
@@ -112,6 +113,7 @@ describe('ContentBase', () => {
       req.get('/bar/').expect(200, /Heyo/, done);
     });
   });
+
   describe('test listing files in folders without index.html using the option serveIndex:true', () => {
     beforeAll((done) => {
       server = testServer.start(
@@ -140,6 +142,7 @@ describe('ContentBase', () => {
       req.get('/bar/').expect(200, /Heyo/, done);
     });
   });
+
   describe('test listing files in folders without index.html using the option serveIndex default (true)', () => {
     beforeAll((done) => {
       server = testServer.start(
@@ -167,6 +170,7 @@ describe('ContentBase', () => {
       req.get('/bar/').expect(200, /Heyo/, done);
     });
   });
+
   describe('to directories', () => {
     beforeAll((done) => {
       server = testServer.start(
@@ -258,6 +262,7 @@ describe('ContentBase', () => {
   describe('default to PWD', () => {
     beforeAll((done) => {
       jest.spyOn(process, 'cwd').mockImplementation(() => contentBasePublic);
+
       server = testServer.start(config, {}, done);
       req = request(server.app);
     });
@@ -278,6 +283,7 @@ describe('ContentBase', () => {
       // This is a somewhat weird test, but it is important that we mock
       // the PWD here, and test if /other.html in our "fake" PWD really is not requested.
       jest.spyOn(process, 'cwd').mockImplementation(() => contentBasePublic);
+
       server = testServer.start(
         config,
         {
diff --git a/test/Headers.test.js b/test/server/headers-option.test.js
similarity index 88%
rename from test/Headers.test.js
rename to test/server/headers-option.test.js
index 5d7a79689f..813635511f 100644
--- a/test/Headers.test.js
+++ b/test/server/headers-option.test.js
@@ -1,10 +1,10 @@
 'use strict';
 
 const request = require('supertest');
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/simple-config/webpack.config');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/simple-config/webpack.config');
 
-describe('Headers', () => {
+describe('headers option', () => {
   let server;
   let req;
 
diff --git a/test/HistoryApiFallback.test.js b/test/server/historyApiFallback-option.test.js
similarity index 86%
rename from test/HistoryApiFallback.test.js
rename to test/server/historyApiFallback-option.test.js
index 996a1875f2..51ad09c506 100644
--- a/test/HistoryApiFallback.test.js
+++ b/test/server/historyApiFallback-option.test.js
@@ -2,12 +2,12 @@
 
 const path = require('path');
 const request = require('supertest');
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/historyapifallback-config/webpack.config');
-const config2 = require('./fixtures/historyapifallback-2-config/webpack.config');
-const config3 = require('./fixtures/historyapifallback-3-config/webpack.config');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/historyapifallback-config/webpack.config');
+const config2 = require('../fixtures/historyapifallback-2-config/webpack.config');
+const config3 = require('../fixtures/historyapifallback-3-config/webpack.config');
 
-describe('HistoryApiFallback', () => {
+describe('historyApiFallback option', () => {
   let server;
   let req;
 
@@ -60,9 +60,9 @@ describe('HistoryApiFallback', () => {
       server = testServer.start(
         config2,
         {
-          contentBase: path.join(
+          contentBase: path.resolve(
             __dirname,
-            'fixtures/historyapifallback-2-config'
+            '../fixtures/historyapifallback-2-config'
           ),
           historyApiFallback: {
             index: '/bar.html',
@@ -96,7 +96,9 @@ describe('HistoryApiFallback', () => {
           if (err) {
             done(err);
           }
+
           expect(res.body.toString().trim()).toEqual('Random file');
+
           done();
         });
     });
@@ -130,9 +132,9 @@ describe('HistoryApiFallback', () => {
       server = testServer.start(
         config2,
         {
-          contentBase: path.join(
+          contentBase: path.resolve(
             __dirname,
-            'fixtures/historyapifallback-2-config'
+            '../fixtures/historyapifallback-2-config'
           ),
           historyApiFallback: {
             rewrites: [
@@ -179,9 +181,9 @@ describe('HistoryApiFallback', () => {
       server = testServer.start(
         config3,
         {
-          contentBase: path.join(
+          contentBase: path.resolve(
             __dirname,
-            'fixtures/historyapifallback-3-config'
+            '../fixtures/historyapifallback-3-config'
           ),
           historyApiFallback: true,
         },
diff --git a/test/server/host-option.test.js b/test/server/host-option.test.js
new file mode 100644
index 0000000000..043c7d5536
--- /dev/null
+++ b/test/server/host-option.test.js
@@ -0,0 +1,161 @@
+'use strict';
+
+const request = require('supertest');
+const config = require('../fixtures/simple-config/webpack.config');
+const testServer = require('../helpers/test-server');
+
+describe('host option', () => {
+  let server = null;
+  let req = null;
+
+  describe('is not be specified', () => {
+    beforeAll((done) => {
+      server = testServer.start(config, {}, done);
+      req = request(server.app);
+    });
+
+    it('server address', () => {
+      const address = server.listeningApp.address();
+
+      expect(address.address).toBe('127.0.0.1');
+      expect(address.port).toBe(8080);
+    });
+
+    it('Request to index', (done) => {
+      req.get('/').expect(200, done);
+    });
+
+    afterAll(testServer.close);
+  });
+
+  describe('is undefined', () => {
+    beforeAll((done) => {
+      server = testServer.start(
+        config,
+        {
+          // eslint-disable-next-line no-undefined
+          host: undefined,
+        },
+        done
+      );
+      req = request(server.app);
+    });
+
+    it('server address', () => {
+      const address = server.listeningApp.address();
+
+      expect(address.address).toBe('::');
+      expect(address.port).toBe(8080);
+    });
+
+    it('Request to index', (done) => {
+      req.get('/').expect(200, done);
+    });
+
+    afterAll(testServer.close);
+  });
+
+  describe('is null', () => {
+    beforeAll((done) => {
+      server = testServer.start(
+        config,
+        {
+          host: null,
+        },
+        done
+      );
+      req = request(server.app);
+    });
+
+    it('server address', () => {
+      const address = server.listeningApp.address();
+
+      expect(address.address).toBe('::');
+      expect(address.port).toBe(8080);
+    });
+
+    it('Request to index', (done) => {
+      req.get('/').expect(200, done);
+    });
+
+    afterAll(testServer.close);
+  });
+
+  describe('is 127.0.0.1 (IPv4)', () => {
+    beforeAll((done) => {
+      server = testServer.start(
+        config,
+        {
+          host: '127.0.0.1',
+        },
+        done
+      );
+      req = request(server.app);
+    });
+
+    it('server address', () => {
+      const address = server.listeningApp.address();
+
+      expect(address.address).toBe('127.0.0.1');
+      expect(address.port).toBe(8080);
+    });
+
+    it('Request to index', (done) => {
+      req.get('/').expect(200, done);
+    });
+
+    afterAll(testServer.close);
+  });
+
+  describe('is localhost', () => {
+    beforeAll((done) => {
+      server = testServer.start(
+        config,
+        {
+          host: 'localhost',
+        },
+        done
+      );
+      req = request(server.app);
+    });
+
+    it('server address', () => {
+      const address = server.listeningApp.address();
+
+      expect(address.address).toBe('127.0.0.1');
+      expect(address.port).toBe(8080);
+    });
+
+    it('Request to index', (done) => {
+      req.get('/').expect(200, done);
+    });
+
+    afterAll(testServer.close);
+  });
+
+  describe('is 0.0.0.0', () => {
+    beforeAll((done) => {
+      server = testServer.start(
+        config,
+        {
+          host: '0.0.0.0',
+        },
+        done
+      );
+      req = request(server.app);
+    });
+
+    it('server address', () => {
+      const address = server.listeningApp.address();
+
+      expect(address.address).toBe('0.0.0.0');
+      expect(address.port).toBe(8080);
+    });
+
+    it('Request to index', (done) => {
+      req.get('/').expect(200, done);
+    });
+
+    afterAll(testServer.close);
+  });
+});
diff --git a/test/Hot.test.js b/test/server/hot-option.test.js
similarity index 72%
rename from test/Hot.test.js
rename to test/server/hot-option.test.js
index 3109340a9e..3754e6ea7d 100644
--- a/test/Hot.test.js
+++ b/test/server/hot-option.test.js
@@ -1,11 +1,11 @@
 'use strict';
 
 const request = require('supertest');
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/client-config/webpack.config');
-const multiCompilerConfig = require('./fixtures/multi-compiler-config/webpack.config');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/client-config/webpack.config');
+const multiCompilerConfig = require('../fixtures/multi-compiler-config/webpack.config');
 
-describe('Hot Module Replacement (hot/hotOnly options)', () => {
+describe('hot option', () => {
   let server;
   let req;
 
@@ -30,29 +30,6 @@ describe('Hot Module Replacement (hot/hotOnly options)', () => {
     });
   });
 
-  describe('simple hotOnly config entries', () => {
-    beforeAll((done) => {
-      const options = {
-        port: 9000,
-        inline: true,
-        hotOnly: true,
-        watchOptions: {
-          poll: true,
-        },
-      };
-      server = testServer.startAwaitingCompilation(config, options, done);
-      req = request(server.app);
-    });
-
-    afterAll(testServer.close);
-
-    it('should include hotOnly script in the bundle', (done) => {
-      req
-        .get('/main.js')
-        .expect(200, /webpack\/hot\/only-dev-server\.js/, done);
-    });
-  });
-
   describe('multi compiler hot config entries', () => {
     beforeAll((done) => {
       const options = {
@@ -142,40 +119,6 @@ describe('Hot Module Replacement (hot/hotOnly options)', () => {
     afterAll(testServer.close);
   });
 
-  describe('simple hotOnly config HMR plugin', () => {
-    it('should register the HMR plugin before compilation is complete', (done) => {
-      let pluginFound = false;
-      const options = {
-        port: 9000,
-        inline: true,
-        hotOnly: true,
-        watchOptions: {
-          poll: true,
-        },
-      };
-      const fullSetup = testServer.startAwaitingCompilationFullSetup(
-        config,
-        options,
-        () => {
-          expect(pluginFound).toBeTruthy();
-          done();
-        }
-      );
-
-      const compiler = fullSetup.compiler;
-      compiler.hooks.compilation.intercept({
-        register: (tapInfo) => {
-          if (tapInfo.name === 'HotModuleReplacementPlugin') {
-            pluginFound = true;
-          }
-          return tapInfo;
-        },
-      });
-    });
-
-    afterAll(testServer.close);
-  });
-
   describe('multi compiler hot config HMR plugin', () => {
     it('should register the HMR plugin before compilation is complete', (done) => {
       let pluginFound = false;
diff --git a/test/server/hotOnly-option.test.js b/test/server/hotOnly-option.test.js
new file mode 100644
index 0000000000..0e48019381
--- /dev/null
+++ b/test/server/hotOnly-option.test.js
@@ -0,0 +1,67 @@
+'use strict';
+
+const request = require('supertest');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/client-config/webpack.config');
+
+describe('hotOnly options', () => {
+  let server;
+  let req;
+
+  describe('simple hotOnly config entries', () => {
+    beforeAll((done) => {
+      const options = {
+        port: 9000,
+        inline: true,
+        hotOnly: true,
+        watchOptions: {
+          poll: true,
+        },
+      };
+      server = testServer.startAwaitingCompilation(config, options, done);
+      req = request(server.app);
+    });
+
+    afterAll(testServer.close);
+
+    it('should include hotOnly script in the bundle', (done) => {
+      req
+        .get('/main.js')
+        .expect(200, /webpack\/hot\/only-dev-server\.js/, done);
+    });
+  });
+
+  describe('simple hotOnly config HMR plugin', () => {
+    it('should register the HMR plugin before compilation is complete', (done) => {
+      let pluginFound = false;
+      const options = {
+        port: 9000,
+        inline: true,
+        hotOnly: true,
+        watchOptions: {
+          poll: true,
+        },
+      };
+      const fullSetup = testServer.startAwaitingCompilationFullSetup(
+        config,
+        options,
+        () => {
+          expect(pluginFound).toBeTruthy();
+          done();
+        }
+      );
+
+      const compiler = fullSetup.compiler;
+      compiler.hooks.compilation.intercept({
+        register: (tapInfo) => {
+          if (tapInfo.name === 'HotModuleReplacementPlugin') {
+            pluginFound = true;
+          }
+          return tapInfo;
+        },
+      });
+    });
+
+    afterAll(testServer.close);
+  });
+});
diff --git a/test/Http2.test.js b/test/server/http2-option.test.js
similarity index 92%
rename from test/Http2.test.js
rename to test/server/http2-option.test.js
index 4433006c74..1dd74c68e9 100644
--- a/test/Http2.test.js
+++ b/test/server/http2-option.test.js
@@ -3,15 +3,15 @@
 const path = require('path');
 const request = require('supertest');
 const semver = require('semver');
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/contentbase-config/webpack.config');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/contentbase-config/webpack.config');
 
-const contentBasePublic = path.join(
+const contentBasePublic = path.resolve(
   __dirname,
-  'fixtures/contentbase-config/public'
+  '../fixtures/contentbase-config/public'
 );
 
-describe('http2', () => {
+describe('http2 option', () => {
   let server;
   let req;
 
diff --git a/test/Https.test.js b/test/server/https-option.test.js
similarity index 84%
rename from test/Https.test.js
rename to test/server/https-option.test.js
index 8f780ac9f3..189bd48286 100644
--- a/test/Https.test.js
+++ b/test/server/https-option.test.js
@@ -3,25 +3,25 @@
 const path = require('path');
 const fs = require('fs');
 const request = require('supertest');
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/contentbase-config/webpack.config');
-const skipTestOnWindows = require('./helpers/conditional-test')
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/contentbase-config/webpack.config');
+const skipTestOnWindows = require('../helpers/conditional-test')
   .skipTestOnWindows;
 
-const httpsCertificateDirectory = path.join(
+const httpsCertificateDirectory = path.resolve(
   __dirname,
-  'fixtures/https-certificate'
+  '../fixtures/https-certificate'
 );
-const contentBasePublic = path.join(
+const contentBasePublic = path.resolve(
   __dirname,
-  'fixtures/contentbase-config/public'
+  '../fixtures/contentbase-config/public'
 );
 
-describe('HTTPS', () => {
+describe('https option', () => {
   let server;
   let req;
 
-  describe('is boolean', () => {
+  describe('as a boolean', () => {
     beforeAll((done) => {
       server = testServer.start(
         config,
@@ -43,7 +43,7 @@ describe('HTTPS', () => {
     });
   });
 
-  describe('ca, pfx, key and cert are buffer', () => {
+  describe('as an object when ca, pfx, key and cert are buffer', () => {
     beforeAll((done) => {
       server = testServer.start(
         config,
@@ -73,7 +73,7 @@ describe('HTTPS', () => {
     });
   });
 
-  describe('ca, pfx, key and cert are paths', () => {
+  describe('as an object when ca, pfx, key and cert are paths', () => {
     beforeAll((done) => {
       server = testServer.start(
         config,
@@ -97,7 +97,7 @@ describe('HTTPS', () => {
     });
   });
 
-  describe('ca, pfx, key and cert are symlinks', () => {
+  describe('as an object when ca, pfx, key and cert are symlinks', () => {
     if (skipTestOnWindows('Symlinks are not supported on Windows')) {
       return;
     }
@@ -127,7 +127,7 @@ describe('HTTPS', () => {
     afterAll(testServer.close);
   });
 
-  describe('ca, pfx, key and cert are raw strings', () => {
+  describe('as an object when ca, pfx, key and cert are raw strings', () => {
     beforeAll((done) => {
       server = testServer.start(
         config,
diff --git a/test/Inline.test.js b/test/server/inline-option.test.js
similarity index 89%
rename from test/Inline.test.js
rename to test/server/inline-option.test.js
index 00f7a273c7..c25b953401 100644
--- a/test/Inline.test.js
+++ b/test/server/inline-option.test.js
@@ -1,11 +1,11 @@
 'use strict';
 
 const request = require('supertest');
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/client-config/webpack.config');
-const multiCompilerConfig = require('./fixtures/multi-compiler-config/webpack.config');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/client-config/webpack.config');
+const multiCompilerConfig = require('../fixtures/multi-compiler-config/webpack.config');
 
-describe('inline', () => {
+describe('inline option', () => {
   let server;
   let req;
 
diff --git a/test/Lazy.test.js b/test/server/lazy-option.test.js
similarity index 75%
rename from test/Lazy.test.js
rename to test/server/lazy-option.test.js
index 4641c7f1c9..515126f8ed 100644
--- a/test/Lazy.test.js
+++ b/test/server/lazy-option.test.js
@@ -1,9 +1,9 @@
 'use strict';
 
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/simple-config/webpack.config');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/simple-config/webpack.config');
 
-describe('Lazy', () => {
+describe('lazy option', () => {
   afterEach(testServer.close);
 
   it('without filename option it should throw an error', () => {
diff --git a/test/LiveReload.test.js b/test/server/liveReload-option.test.js
similarity index 90%
rename from test/LiveReload.test.js
rename to test/server/liveReload-option.test.js
index a4f66c15b2..6226f4d771 100644
--- a/test/LiveReload.test.js
+++ b/test/server/liveReload-option.test.js
@@ -2,16 +2,17 @@
 
 const path = require('path');
 const fs = require('fs');
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/contentbase-config/webpack.config');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/contentbase-config/webpack.config');
 
-const contentBasePublic = path.join(
+const contentBasePublic = path.resolve(
   __dirname,
-  'fixtures/contentbase-config/public'
+  '../fixtures/contentbase-config/public'
 );
 
-describe('liveReload', () => {
+describe('liveReload option', () => {
   let server;
+
   describe('Test disabling live reloading', () => {
     const nestedFile = path.join(contentBasePublic, 'assets/example.txt');
 
diff --git a/test/server/mimeTypes-option.test.js b/test/server/mimeTypes-option.test.js
new file mode 100644
index 0000000000..2fcde68a67
--- /dev/null
+++ b/test/server/mimeTypes-option.test.js
@@ -0,0 +1,60 @@
+'use strict';
+
+const request = require('supertest');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/simple-config/webpack.config');
+
+describe('mimeTypes option', () => {
+  describe('as an object', () => {
+    afterEach(testServer.close);
+
+    it('should remapping mime type without force should throw an error', () => {
+      expect(() => {
+        testServer.start(config, {
+          mimeTypes: { 'application/octet-stream': ['js'] },
+        });
+      }).toThrow(/Attempt to change mapping for/);
+    });
+
+    it('should remapping mime type with force should not throw an error', (done) => {
+      testServer.start(
+        config,
+        {
+          mimeTypes: {
+            typeMap: { 'application/octet-stream': ['js'] },
+            force: true,
+          },
+        },
+        done
+      );
+    });
+  });
+
+  describe('as an object with force option', () => {
+    let server;
+    let req;
+
+    beforeAll((done) => {
+      server = testServer.start(
+        config,
+        {
+          mimeTypes: {
+            typeMap: { 'application/octet-stream': ['js'] },
+            force: true,
+          },
+        },
+        done
+      );
+      req = request(server.app);
+    });
+
+    afterAll(testServer.close);
+
+    it('request to bundle file with modified mime type', (done) => {
+      req
+        .get('/main.js')
+        .expect('Content-Type', /application\/octet-stream/)
+        .expect(200, done);
+    });
+  });
+});
diff --git a/test/onListening.test.js b/test/server/onListening-option.test.js
similarity index 67%
rename from test/onListening.test.js
rename to test/server/onListening-option.test.js
index 249507aca5..43db18eec8 100644
--- a/test/onListening.test.js
+++ b/test/server/onListening-option.test.js
@@ -1,9 +1,9 @@
 'use strict';
 
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/simple-config/webpack.config');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/simple-config/webpack.config');
 
-describe('Before And After options', () => {
+describe('onListening option', () => {
   let onListeningIsRunning = false;
 
   beforeAll((done) => {
@@ -24,7 +24,7 @@ describe('Before And After options', () => {
 
   afterAll(testServer.close);
 
-  it('should handle before route', () => {
+  it('should runs onListening callback', () => {
     expect(onListeningIsRunning).toBe(true);
   });
 });
diff --git a/test/server/open-option.test.js b/test/server/open-option.test.js
new file mode 100644
index 0000000000..c0f1768b99
--- /dev/null
+++ b/test/server/open-option.test.js
@@ -0,0 +1,32 @@
+'use strict';
+
+jest.mock('opn');
+
+const webpack = require('webpack');
+const opn = require('opn');
+const Server = require('../../lib/Server');
+const config = require('../fixtures/simple-config/webpack.config');
+
+opn.mockImplementation(() => {
+  return {
+    catch: jest.fn(),
+  };
+});
+
+describe('open option', () => {
+  it('should open', (done) => {
+    const compiler = webpack(config);
+    const server = new Server(compiler, {
+      open: true,
+    });
+
+    compiler.hooks.done.tap('webpack-dev-server', () => {
+      expect(opn.mock.calls[0]).toEqual(['http://localhost:8080/', {}]);
+      expect(opn.mock.invocationCallOrder[0]).toEqual(1);
+      server.close(done);
+    });
+
+    compiler.run(() => {});
+    server.listen(8080, 'localhost');
+  });
+});
diff --git a/test/server/port-option.test.js b/test/server/port-option.test.js
new file mode 100644
index 0000000000..0cb2046962
--- /dev/null
+++ b/test/server/port-option.test.js
@@ -0,0 +1,138 @@
+'use strict';
+
+const request = require('supertest');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/simple-config/webpack.config');
+
+describe('port', () => {
+  let server = null;
+  let req = null;
+
+  describe('is not be specified', () => {
+    beforeAll((done) => {
+      server = testServer.start(config, {}, done);
+      req = request(server.app);
+    });
+
+    it('server address', () => {
+      const address = server.listeningApp.address();
+
+      expect(address.address).toBe('127.0.0.1');
+      // Random port
+      expect(address.port).toBeDefined();
+    });
+
+    it('Request to index', (done) => {
+      req.get('/').expect(200, done);
+    });
+
+    afterAll(testServer.close);
+  });
+
+  describe('is undefined', () => {
+    beforeAll((done) => {
+      server = testServer.start(
+        config,
+        {
+          // eslint-disable-next-line no-undefined
+          port: undefined,
+        },
+        done
+      );
+      req = request(server.app);
+    });
+
+    it('server address', () => {
+      const address = server.listeningApp.address();
+
+      expect(address.address).toBe('127.0.0.1');
+      // Random port
+      expect(address.port).toBeDefined();
+    });
+
+    it('Request to index', (done) => {
+      req.get('/').expect(200, done);
+    });
+
+    afterAll(testServer.close);
+  });
+
+  describe('is null', () => {
+    beforeAll((done) => {
+      server = testServer.start(
+        config,
+        {
+          port: null,
+        },
+        done
+      );
+      req = request(server.app);
+    });
+
+    it('server address', () => {
+      const address = server.listeningApp.address();
+
+      expect(address.address).toBe('127.0.0.1');
+      // Random port
+      expect(address.port).toBeDefined();
+    });
+
+    it('Request to index', (done) => {
+      req.get('/').expect(200, done);
+    });
+
+    afterAll(testServer.close);
+  });
+
+  describe('is "33333"', () => {
+    beforeAll((done) => {
+      server = testServer.start(
+        config,
+        {
+          port: '33333',
+        },
+        done
+      );
+      req = request(server.app);
+    });
+
+    it('server address', () => {
+      const address = server.listeningApp.address();
+
+      expect(address.address).toBe('127.0.0.1');
+      expect(address.port).toBe(33333);
+    });
+
+    it('Request to index', (done) => {
+      req.get('/').expect(200, done);
+    });
+
+    afterAll(testServer.close);
+  });
+
+  describe('is 33333', () => {
+    beforeAll((done) => {
+      server = testServer.start(
+        config,
+        {
+          port: '33333',
+        },
+        done
+      );
+      req = request(server.app);
+    });
+
+    it('server address', () => {
+      const address = server.listeningApp.address();
+
+      expect(address.address).toBe('127.0.0.1');
+      expect(address.port).toBe(33333);
+    });
+
+    it('Request to index', (done) => {
+      req.get('/').expect(200, done);
+    });
+
+    afterAll(testServer.close);
+  });
+});
diff --git a/test/Proxy.test.js b/test/server/proxy-option.test.js
similarity index 93%
rename from test/Proxy.test.js
rename to test/server/proxy-option.test.js
index 954e8efb59..e28c8e6126 100644
--- a/test/Proxy.test.js
+++ b/test/server/proxy-option.test.js
@@ -5,11 +5,11 @@ const request = require('supertest');
 const express = require('express');
 const bodyParser = require('body-parser');
 const WebSocket = require('ws');
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/proxy-config/webpack.config');
+const testServer = require('../helpers/test-server');
+const config = require('../fixtures/proxy-config/webpack.config');
 
 const WebSocketServer = WebSocket.Server;
-const contentBase = path.join(__dirname, 'fixtures/proxy-config');
+const contentBase = path.resolve(__dirname, '../fixtures/proxy-config');
 
 const proxyOptionPathsAsProperties = {
   '/proxy1': {
@@ -21,6 +21,7 @@ const proxyOptionPathsAsProperties = {
   },
   '/foo': {
     bypass(req) {
+      console.log(req.path);
       if (/\.html$/.test(req.path)) {
         return '/index.html';
       }
@@ -57,6 +58,7 @@ function startProxyServers() {
   const listeners = [];
   const proxy1 = express();
   const proxy2 = express();
+
   proxy1.get('/proxy1', (req, res) => {
     res.send('from proxy1');
   });
@@ -66,8 +68,10 @@ function startProxyServers() {
   proxy2.get('/proxy2', (req, res) => {
     res.send('from proxy2');
   });
+
   listeners.push(proxy1.listen(9000));
   listeners.push(proxy2.listen(9001));
+
   // return a function to shutdown proxy servers
   return function proxy() {
     listeners.forEach((listener) => {
@@ -76,8 +80,8 @@ function startProxyServers() {
   };
 }
 
-describe('Proxy', () => {
-  describe('proxy options is an object of paths as properties', () => {
+describe('proxy option', () => {
+  describe('as an object of paths with properties', () => {
     let server;
     let req;
     let closeProxyServers;
@@ -133,7 +137,7 @@ describe('Proxy', () => {
     });
   });
 
-  describe('proxy option is an object', () => {
+  describe('as an option is an object', () => {
     let server;
     let req;
     let closeProxyServers;
@@ -163,7 +167,7 @@ describe('Proxy', () => {
     });
   });
 
-  describe('proxy option is an array', () => {
+  describe('as an array', () => {
     let server;
     let req;
     let closeProxyServers;
@@ -197,7 +201,7 @@ describe('Proxy', () => {
     });
   });
 
-  describe('sharing a proxy option', () => {
+  describe('should sharing a proxy option', () => {
     let server;
     let req;
     let listener;
@@ -207,10 +211,13 @@ describe('Proxy', () => {
 
     beforeAll((done) => {
       const proxy = express();
+
       proxy.get('*', (proxyReq, res) => {
         res.send('from proxy');
       });
+
       listener = proxy.listen(9000);
+
       server = testServer.start(
         config,
         {
@@ -241,7 +248,7 @@ describe('Proxy', () => {
     });
   });
 
-  describe('External websocket upgrade', () => {
+  describe('should handles external websocket upgrade', () => {
     let ws;
     let wsServer;
     let responseMessage;
@@ -291,7 +298,7 @@ describe('Proxy', () => {
     });
   });
 
-  describe('should support http methods', () => {
+  describe('should supports http methods', () => {
     let server;
     let req;
     let listener;
diff --git a/test/ServerMode.test.js b/test/server/serverMode-option.test.js
similarity index 82%
rename from test/ServerMode.test.js
rename to test/server/serverMode-option.test.js
index 288322e1f4..ebe5aff3a8 100644
--- a/test/ServerMode.test.js
+++ b/test/server/serverMode-option.test.js
@@ -5,12 +5,12 @@
 */
 const request = require('supertest');
 const sockjs = require('sockjs');
-const SockJSServer = require('../lib/servers/SockJSServer');
-const config = require('./fixtures/simple-config/webpack.config');
-const testServer = require('./helpers/test-server');
-const BaseServer = require('./../lib/servers/BaseServer');
+const SockJSServer = require('../../lib/servers/SockJSServer');
+const config = require('../fixtures/simple-config/webpack.config');
+const testServer = require('../helpers/test-server');
+const BaseServer = require('../../lib/servers/BaseServer');
 
-describe('serverMode', () => {
+describe('serverMode option', () => {
   let server;
   let req;
 
@@ -19,7 +19,8 @@ describe('serverMode', () => {
     req = null;
     server = null;
   });
-  describe("supplying 'sockjs' as a string", () => {
+
+  describe('as a string ("sockjs")', () => {
     beforeEach((done) => {
       server = testServer.start(
         config,
@@ -36,12 +37,12 @@ describe('serverMode', () => {
     });
   });
 
-  describe('supplying path to sockjs implementation', () => {
+  describe('as a path ("sockjs")', () => {
     beforeEach((done) => {
       server = testServer.start(
         config,
         {
-          serverMode: require.resolve('../lib/servers/SockJSServer'),
+          serverMode: require.resolve('../../lib/servers/SockJSServer'),
         },
         done
       );
@@ -53,7 +54,7 @@ describe('serverMode', () => {
     });
   });
 
-  describe('supplying sockjs implementation class', () => {
+  describe('as a class ("sockjs")', () => {
     beforeEach((done) => {
       server = testServer.start(
         config,
@@ -70,7 +71,7 @@ describe('serverMode', () => {
     });
   });
 
-  describe('custom sockjs implementation', () => {
+  describe('as a class (custom "sockjs" implementation)', () => {
     it('uses supplied server implementation', (done) => {
       server = testServer.start(
         config,
@@ -117,7 +118,7 @@ describe('serverMode', () => {
     });
   });
 
-  describe('supplying nonexistent path', () => {
+  describe('as a path with nonexistent path', () => {
     it('should throw an error', () => {
       expect(() => {
         server = testServer.start(
diff --git a/test/SockJSServer.test.js b/test/server/servers/SockJSServer.test.js
similarity index 95%
rename from test/SockJSServer.test.js
rename to test/server/servers/SockJSServer.test.js
index 9456f277f0..86335b5c7a 100644
--- a/test/SockJSServer.test.js
+++ b/test/server/servers/SockJSServer.test.js
@@ -3,7 +3,7 @@
 const http = require('http');
 const express = require('express');
 const SockJS = require('sockjs-client/dist/sockjs');
-const SockJSServer = require('../lib/servers/SockJSServer');
+const SockJSServer = require('../../../lib/servers/SockJSServer');
 
 describe('SockJSServer', () => {
   let socketServer;
@@ -12,6 +12,7 @@ describe('SockJSServer', () => {
   beforeAll((done) => {
     // eslint-disable-next-line new-cap
     const app = new express();
+
     listeningApp = http.createServer(app);
     listeningApp.listen(8080, 'localhost', () => {
       const server = {
@@ -22,7 +23,9 @@ describe('SockJSServer', () => {
         sockPath: '/sockjs-node',
         listeningApp,
       };
+
       socketServer = new SockJSServer(server);
+
       done();
     });
   });
@@ -30,6 +33,7 @@ describe('SockJSServer', () => {
   describe('server', () => {
     it('should recieve connection, send message, and close client', (done) => {
       const data = [];
+
       socketServer.onConnection((connection) => {
         data.push('open');
         socketServer.send(connection, 'hello world');
diff --git a/test/Socket.test.js b/test/server/sockPath-option.test.js
similarity index 87%
rename from test/Socket.test.js
rename to test/server/sockPath-option.test.js
index 0220b60eb0..5542dc985d 100644
--- a/test/Socket.test.js
+++ b/test/server/sockPath-option.test.js
@@ -1,10 +1,10 @@
 'use strict';
 
 const request = require('supertest');
-const config = require('./fixtures/simple-config/webpack.config');
-const testServer = require('./helpers/test-server');
+const config = require('../fixtures/simple-config/webpack.config');
+const testServer = require('../helpers/test-server');
 
-describe('socket options', () => {
+describe('sockPath options', () => {
   let server;
   let req;
 
@@ -13,6 +13,7 @@ describe('socket options', () => {
     req = null;
     server = null;
   });
+
   describe('default behavior', () => {
     beforeEach((done) => {
       server = testServer.start(config, {}, done);
@@ -30,6 +31,7 @@ describe('socket options', () => {
 
   describe('socksPath option', () => {
     const path = '/foo/test/bar';
+
     beforeEach((done) => {
       server = testServer.start(
         config,
diff --git a/test/server/stats-option.test.js b/test/server/stats-option.test.js
new file mode 100644
index 0000000000..299ce7aa63
--- /dev/null
+++ b/test/server/stats-option.test.js
@@ -0,0 +1,59 @@
+'use strict';
+
+const webpack = require('webpack');
+const Server = require('../../lib/Server');
+const config = require('../fixtures/simple-config/webpack.config');
+
+describe('stats option', () => {
+  it(`should works with difference stats values (contains 'hash', 'assets', 'warnings' and 'errors')`, () => {
+    const allStats = [
+      {},
+      // eslint-disable-next-line no-undefined
+      undefined,
+      false,
+      'errors-only',
+      {
+        assets: false,
+      },
+    ];
+
+    return allStats.reduce((p, stats) => {
+      return p.then(() => {
+        return new Promise((resolve) => {
+          const compiler = webpack(config);
+          const server = new Server(compiler, { stats });
+
+          compiler.hooks.done.tap('webpack-dev-server', (s) => {
+            expect(Object.keys(server.getStats(s))).toMatchSnapshot();
+
+            server.close(resolve);
+          });
+
+          compiler.run(() => {});
+          server.listen(8080, 'localhost');
+        });
+      });
+    }, Promise.resolve());
+  });
+
+  it('should respect warningsFilter', (done) => {
+    const compiler = webpack(config);
+    const server = new Server(compiler, {
+      stats: { warningsFilter: 'test' },
+    });
+
+    compiler.hooks.done.tap('webpack-dev-server', (s) => {
+      s.compilation.warnings = ['test', 'another warning'];
+
+      const output = server.getStats(s);
+
+      expect(output.warnings.length).toBe(1);
+      expect(output.warnings[0]).toBe('another warning');
+
+      server.close(done);
+    });
+
+    compiler.run(() => {});
+    server.listen(8080, 'localhost');
+  });
+});
diff --git a/test/__snapshots__/CreateConfig.test.js.snap b/test/server/utils/__snapshots__/createConfig.test.js.snap
similarity index 100%
rename from test/__snapshots__/CreateConfig.test.js.snap
rename to test/server/utils/__snapshots__/createConfig.test.js.snap
diff --git a/test/__snapshots__/Util.test.js.snap b/test/server/utils/__snapshots__/findPort.test.js.snap
similarity index 100%
rename from test/__snapshots__/Util.test.js.snap
rename to test/server/utils/__snapshots__/findPort.test.js.snap
diff --git a/test/Entry.test.js b/test/server/utils/addEntries.test.js
similarity index 85%
rename from test/Entry.test.js
rename to test/server/utils/addEntries.test.js
index 0ee7538b82..608bd61a30 100644
--- a/test/Entry.test.js
+++ b/test/server/utils/addEntries.test.js
@@ -1,23 +1,15 @@
 'use strict';
 
-/* eslint-disable
-  import/order,
-  arrow-parens,
-  array-bracket-spacing
-*/
 const path = require('path');
-
 const webpack = require('webpack');
-
-const addEntries = require('../lib/utils/addEntries');
-
-const config = require('./fixtures/simple-config/webpack.config');
-const configEntryAsFunction = require('./fixtures/entry-as-function/webpack.config');
+const addEntries = require('../../../lib/utils/addEntries');
+const config = require('./../../fixtures/simple-config/webpack.config');
+const configEntryAsFunction = require('./../../fixtures/entry-as-function/webpack.config');
 
 const normalize = (entry) => entry.split(path.sep).join('/');
 
-describe('Entry', () => {
-  it('adds devServer entry points to a single entry point', () => {
+describe('addEntries util', () => {
+  it('should adds devServer entry points to a single entry point', () => {
     const webpackOptions = Object.assign({}, config);
     const devServerOptions = {};
 
@@ -30,7 +22,7 @@ describe('Entry', () => {
     expect(normalize(webpackOptions.entry[1])).toEqual('./foo.js');
   });
 
-  it('adds devServer entry points to a multi-module entry point', () => {
+  it('should adds devServer entry points to a multi-module entry point', () => {
     const webpackOptions = Object.assign({}, config, {
       entry: ['./foo.js', './bar.js'],
     });
@@ -47,7 +39,7 @@ describe('Entry', () => {
     expect(webpackOptions.entry[2]).toEqual('./bar.js');
   });
 
-  it('adds devServer entry points to a multi entry point object', () => {
+  it('should adds devServer entry points to a multi entry point object', () => {
     const webpackOptions = Object.assign({}, config, {
       entry: {
         foo: './foo.js',
@@ -68,7 +60,7 @@ describe('Entry', () => {
     expect(webpackOptions.entry.bar[1]).toEqual('./bar.js');
   });
 
-  it('defaults to src if no entry point is given', () => {
+  it('should set defaults to src if no entry point is given', () => {
     const webpackOptions = {};
     const devServerOptions = {};
 
@@ -78,7 +70,7 @@ describe('Entry', () => {
     expect(webpackOptions.entry[1]).toEqual('./src');
   });
 
-  it('preserves dynamic entry points', (done) => {
+  it('should preserves dynamic entry points', (done) => {
     let i = 0;
     const webpackOptions = {
       // simulate dynamic entry
@@ -108,7 +100,7 @@ describe('Entry', () => {
       .catch(done);
   });
 
-  it('preserves asynchronous dynamic entry points', (done) => {
+  it('should preserves asynchronous dynamic entry points', (done) => {
     let i = 0;
     const webpackOptions = {
       // simulate async dynamic entry
@@ -140,7 +132,7 @@ describe('Entry', () => {
       .catch(done);
   });
 
-  it("prepends webpack's hot reload client script", () => {
+  it("should prepends webpack's hot reload client script", () => {
     const webpackOptions = Object.assign({}, config, {
       entry: {
         app: './app.js',
@@ -161,7 +153,7 @@ describe('Entry', () => {
     expect(hotClientScript).toEqual(require.resolve(hotClientScript));
   });
 
-  it("prepends webpack's hot-only client script", () => {
+  it("should prepends webpack's hot-only client script", () => {
     const webpackOptions = Object.assign({}, config, {
       entry: {
         app: './app.js',
@@ -182,7 +174,7 @@ describe('Entry', () => {
     expect(hotClientScript).toEqual(require.resolve(hotClientScript));
   });
 
-  it("doesn't add the HMR plugin if not hot and no plugins", () => {
+  it("should doesn't add the HMR plugin if not hot and no plugins", () => {
     const webpackOptions = Object.assign({}, config);
     const devServerOptions = {};
 
@@ -191,7 +183,7 @@ describe('Entry', () => {
     expect('plugins' in webpackOptions).toBeFalsy();
   });
 
-  it("doesn't add the HMR plugin if not hot and empty plugins", () => {
+  it("should doesn't add the HMR plugin if not hot and empty plugins", () => {
     const webpackOptions = Object.assign({}, config, { plugins: [] });
     const devServerOptions = {};
 
@@ -200,7 +192,7 @@ describe('Entry', () => {
     expect(webpackOptions.plugins).toEqual([]);
   });
 
-  it("doesn't add the HMR plugin if not hot and some plugins", () => {
+  it("should doesn't add the HMR plugin if not hot and some plugins", () => {
     const existingPlugin1 = new webpack.BannerPlugin('happy birthday');
     const existingPlugin2 = new webpack.DefinePlugin({ foo: 'bar' });
     const webpackOptions = Object.assign({}, config, {
@@ -213,7 +205,7 @@ describe('Entry', () => {
     expect(webpackOptions.plugins).toEqual([existingPlugin1, existingPlugin2]);
   });
 
-  it('adds the HMR plugin if hot', () => {
+  it('should adds the HMR plugin if hot', () => {
     const existingPlugin = new webpack.BannerPlugin('bruce');
     const webpackOptions = Object.assign({}, config, {
       plugins: [existingPlugin],
@@ -228,7 +220,7 @@ describe('Entry', () => {
     ]);
   });
 
-  it('adds the HMR plugin if hot-only', () => {
+  it('should adds the HMR plugin if hot-only', () => {
     const webpackOptions = Object.assign({}, config);
     const devServerOptions = { hotOnly: true };
 
@@ -239,7 +231,7 @@ describe('Entry', () => {
     ]);
   });
 
-  it("doesn't add the HMR plugin again if it's already there", () => {
+  it("should doesn't add the HMR plugin again if it's already there", () => {
     const existingPlugin = new webpack.BannerPlugin('bruce');
     const webpackOptions = Object.assign({}, config, {
       plugins: [new webpack.HotModuleReplacementPlugin(), existingPlugin],
@@ -254,7 +246,7 @@ describe('Entry', () => {
     ]);
   });
 
-  it('can prevent duplicate entries from successive calls', () => {
+  it('should can prevent duplicate entries from successive calls', () => {
     const webpackOptions = Object.assign({}, config);
     const devServerOptions = { hot: true };
 
@@ -269,7 +261,7 @@ describe('Entry', () => {
     expect(result.length).toEqual(1);
   });
 
-  it('supports entry as Function', () => {
+  it('should supports entry as Function', () => {
     const webpackOptions = Object.assign({}, configEntryAsFunction);
     const devServerOptions = {};
 
@@ -278,7 +270,7 @@ describe('Entry', () => {
     expect(typeof webpackOptions.entry === 'function').toBe(true);
   });
 
-  it('only prepends devServer entry points to web targets by default', () => {
+  it('should only prepends devServer entry points to web targets by default', () => {
     const webpackOptions = [
       Object.assign({}, config),
       Object.assign({ target: 'web' }, config),
@@ -310,7 +302,7 @@ describe('Entry', () => {
     });
   });
 
-  it('allows selecting compilations to inline the client into', () => {
+  it('should allows selecting compilations to inline the client into', () => {
     const webpackOptions = [
       Object.assign({}, config),
       Object.assign({ target: 'web' }, config),
@@ -342,7 +334,7 @@ describe('Entry', () => {
     });
   });
 
-  it('when hot, prepends the hot runtime to all targets by default', () => {
+  it('should prepends the hot runtime to all targets by default (when hot)', () => {
     const webpackOptions = [
       Object.assign({ target: 'web' }, config),
       Object.assign({ target: 'node' }, config),
@@ -369,7 +361,7 @@ describe('Entry', () => {
     });
   });
 
-  it('allows selecting which compilations to inject the hot runtime into', () => {
+  it('should allows selecting which compilations to inject the hot runtime into', () => {
     const webpackOptions = [
       Object.assign({ target: 'web' }, config),
       Object.assign({ target: 'node' }, config),
diff --git a/test/CreateConfig.test.js b/test/server/utils/createConfig.test.js
similarity index 98%
rename from test/CreateConfig.test.js
rename to test/server/utils/createConfig.test.js
index a0b99047e2..67431598c4 100644
--- a/test/CreateConfig.test.js
+++ b/test/server/utils/createConfig.test.js
@@ -1,9 +1,9 @@
 'use strict';
 
 const path = require('path');
-const createConfig = require('../lib/utils/createConfig');
-const webpackConfig = require('./fixtures/schema/webpack.config.simple');
-const webpackConfigNoStats = require('./fixtures/schema/webpack.config.no-dev-stats');
+const createConfig = require('../../../lib/utils/createConfig');
+const webpackConfig = require('./../../fixtures/schema/webpack.config.simple');
+const webpackConfigNoStats = require('./../../fixtures/schema/webpack.config.no-dev-stats');
 
 const argv = {
   port: 8080,
diff --git a/test/Util.test.js b/test/server/utils/createDomain.test.js
similarity index 56%
rename from test/Util.test.js
rename to test/server/utils/createDomain.test.js
index 9b71e85106..08b839c585 100644
--- a/test/Util.test.js
+++ b/test/server/utils/createDomain.test.js
@@ -1,12 +1,10 @@
 'use strict';
 
-const http = require('http');
 const webpack = require('webpack');
 const internalIp = require('internal-ip');
-const Server = require('../lib/Server');
-const createDomain = require('../lib/utils/createDomain');
-const findPort = require('../lib/utils/findPort');
-const config = require('./fixtures/simple-config/webpack.config');
+const Server = require('../../../lib/Server');
+const createDomain = require('../../../lib/utils/createDomain');
+const config = require('./../../fixtures/simple-config/webpack.config');
 
 describe('check utility functions', () => {
   let compiler;
@@ -116,67 +114,3 @@ describe('check utility functions', () => {
     });
   });
 });
-
-describe('findPort cli utility function', () => {
-  let dummyServers = [];
-
-  afterEach(() => {
-    delete process.env.DEFAULT_PORT_RETRY;
-
-    return dummyServers
-      .reduce((p, server) => {
-        return p.then(() => {
-          return new Promise((resolve) => {
-            server.close(resolve);
-          });
-        });
-      }, Promise.resolve())
-      .then(() => {
-        dummyServers = [];
-      });
-  });
-
-  function createDummyServers(n) {
-    return [...new Array(n)].reduce((p, _, i) => {
-      return p.then(() => {
-        return new Promise((resolve) => {
-          const server = http.createServer();
-          dummyServers.push(server);
-          server.listen(8080 + i, resolve);
-        });
-      });
-    }, Promise.resolve());
-  }
-
-  it('should return the port when the port is specified', () => {
-    process.env.DEFAULT_PORT_RETRY = 5;
-
-    return findPort(8082).then((port) => {
-      expect(port).toEqual(8082);
-    });
-  });
-
-  it('should retry finding the port for up to defaultPortRetry times', () => {
-    const retryCount = 5;
-
-    process.env.DEFAULT_PORT_RETRY = retryCount;
-
-    return createDummyServers(retryCount)
-      .then(findPort)
-      .then((port) => {
-        expect(port).toEqual(8080 + retryCount);
-      });
-  });
-
-  it("should throw the error when the port isn't found", () => {
-    const retryCount = 5;
-
-    process.env.DEFAULT_PORT_RETRY = retryCount;
-
-    return createDummyServers(10)
-      .then(findPort)
-      .catch((err) => {
-        expect(err.message).toMatchSnapshot();
-      });
-  });
-});
diff --git a/test/server/utils/findPort.test.js b/test/server/utils/findPort.test.js
new file mode 100644
index 0000000000..d618a82505
--- /dev/null
+++ b/test/server/utils/findPort.test.js
@@ -0,0 +1,66 @@
+'use strict';
+
+const http = require('http');
+const findPort = require('../../../lib/utils/findPort');
+
+describe('findPort cli utility function', () => {
+  let dummyServers = [];
+
+  afterEach(() => {
+    delete process.env.DEFAULT_PORT_RETRY;
+
+    return dummyServers
+      .reduce((p, server) => {
+        return p.then(() => {
+          return new Promise((resolve) => {
+            server.close(resolve);
+          });
+        });
+      }, Promise.resolve())
+      .then(() => {
+        dummyServers = [];
+      });
+  });
+
+  function createDummyServers(n) {
+    return [...new Array(n)].reduce((p, _, i) => {
+      return p.then(() => {
+        return new Promise((resolve) => {
+          const server = http.createServer();
+          dummyServers.push(server);
+          server.listen(8080 + i, resolve);
+        });
+      });
+    }, Promise.resolve());
+  }
+
+  it('should return the port when the port is specified', () => {
+    process.env.DEFAULT_PORT_RETRY = 5;
+
+    return findPort(8082).then((port) => {
+      expect(port).toEqual(8082);
+    });
+  });
+
+  it('should retry finding the port for up to defaultPortRetry times', () => {
+    const retryCount = 5;
+
+    process.env.DEFAULT_PORT_RETRY = retryCount;
+
+    return createDummyServers(retryCount)
+      .then(findPort)
+      .then((port) => {
+        expect(port).toEqual(8080 + retryCount);
+      });
+  });
+
+  it("should throw the error when the port isn't found", () => {
+    process.env.DEFAULT_PORT_RETRY = 5;
+
+    return createDummyServers(10)
+      .then(findPort)
+      .catch((err) => {
+        expect(err.message).toMatchSnapshot();
+      });
+  });
+});
diff --git a/test/GetSocketServerImplementation.test.js b/test/server/utils/getSocketServerImplementation.test.js
similarity index 77%
rename from test/GetSocketServerImplementation.test.js
rename to test/server/utils/getSocketServerImplementation.test.js
index 830f49513f..51bcdf9143 100644
--- a/test/GetSocketServerImplementation.test.js
+++ b/test/server/utils/getSocketServerImplementation.test.js
@@ -1,9 +1,9 @@
 'use strict';
 
-const getSocketServerImplementation = require('../lib/utils/getSocketServerImplementation');
-const SockJSServer = require('../lib/servers/SockJSServer');
+const getSocketServerImplementation = require('../../../lib/utils/getSocketServerImplementation');
+const SockJSServer = require('../../../lib/servers/SockJSServer');
 
-describe('getSocketServerImplementation', () => {
+describe('getSocketServerImplementation util', () => {
   it("should work with serverMode: 'sockjs'", () => {
     let result;
 
@@ -33,7 +33,7 @@ describe('getSocketServerImplementation', () => {
 
     expect(() => {
       result = getSocketServerImplementation({
-        serverMode: require.resolve('../lib/servers/SockJSServer'),
+        serverMode: require.resolve('../../../lib/servers/SockJSServer'),
       });
     }).not.toThrow();
 
diff --git a/test/Routes.test.js b/test/server/utils/routes.test.js
similarity index 72%
rename from test/Routes.test.js
rename to test/server/utils/routes.test.js
index 75d485fc58..53e1029601 100644
--- a/test/Routes.test.js
+++ b/test/server/utils/routes.test.js
@@ -1,10 +1,10 @@
 'use strict';
 
 const request = require('supertest');
-const testServer = require('./helpers/test-server');
-const config = require('./fixtures/simple-config/webpack.config');
+const testServer = require('../../helpers/test-server');
+const config = require('../../fixtures/simple-config/webpack.config');
 
-describe('Routes', () => {
+describe('routes util', () => {
   let server;
   let req;
 
@@ -15,7 +15,7 @@ describe('Routes', () => {
 
   afterAll(testServer.close);
 
-  it('GET request to live bundle', (done) => {
+  it('should handles GET request to live bundle', (done) => {
     req.get('/__webpack_dev_server__/live.bundle.js').then(({ res }) => {
       expect(res.headers['content-type']).toEqual('application/javascript');
       expect(res.statusCode).toEqual(200);
@@ -23,7 +23,7 @@ describe('Routes', () => {
     });
   });
 
-  it('HEAD request to live bundle', (done) => {
+  it('should handles HEAD request to live bundle', (done) => {
     req.head('/__webpack_dev_server__/live.bundle.js').then(({ res }) => {
       expect(res.headers['content-type']).toEqual('application/javascript');
       expect(res.statusCode).toEqual(200);
@@ -31,7 +31,7 @@ describe('Routes', () => {
     });
   });
 
-  it('GET request to sockjs bundle', (done) => {
+  it('should handles GET request to sockjs bundle', (done) => {
     req.get('/__webpack_dev_server__/sockjs.bundle.js').then(({ res }) => {
       expect(res.headers['content-type']).toEqual('application/javascript');
       expect(res.statusCode).toEqual(200);
@@ -39,7 +39,7 @@ describe('Routes', () => {
     });
   });
 
-  it('HEAD request to sockjs bundle', (done) => {
+  it('should handles HEAD request to sockjs bundle', (done) => {
     req.head('/__webpack_dev_server__/sockjs.bundle.js').then(({ res }) => {
       expect(res.headers['content-type']).toEqual('application/javascript');
       expect(res.statusCode).toEqual(200);
@@ -47,7 +47,7 @@ describe('Routes', () => {
     });
   });
 
-  it('GET request to inline bundle', (done) => {
+  it('should handles GET request to inline bundle', (done) => {
     req.get('/webpack-dev-server.js').then(({ res }) => {
       expect(res.headers['content-type']).toEqual('application/javascript');
       expect(res.statusCode).toEqual(200);
@@ -55,7 +55,7 @@ describe('Routes', () => {
     });
   });
 
-  it('HEAD request to inline bundle', (done) => {
+  it('should handles HEAD request to inline bundle', (done) => {
     req.head('/webpack-dev-server.js').then(({ res }) => {
       expect(res.headers['content-type']).toEqual('application/javascript');
       expect(res.statusCode).toEqual(200);
@@ -63,7 +63,7 @@ describe('Routes', () => {
     });
   });
 
-  it('GET request to live html', (done) => {
+  it('should handles GET request to live html', (done) => {
     req.get('/webpack-dev-server/').then(({ res }) => {
       expect(res.headers['content-type']).toEqual('text/html');
       expect(res.statusCode).toEqual(200);
@@ -71,7 +71,7 @@ describe('Routes', () => {
     });
   });
 
-  it('HEAD request to live html', (done) => {
+  it('should handles HEAD request to live html', (done) => {
     req.head('/webpack-dev-server/').then(({ res }) => {
       expect(res.headers['content-type']).toEqual('text/html');
       expect(res.statusCode).toEqual(200);
@@ -79,7 +79,7 @@ describe('Routes', () => {
     });
   });
 
-  it('GET request to directory index', (done) => {
+  it('should handles GET request to directory index', (done) => {
     req.get('/webpack-dev-server').then(({ res }) => {
       expect(res.headers['content-type']).toEqual('text/html');
       expect(res.statusCode).toEqual(200);
@@ -87,7 +87,7 @@ describe('Routes', () => {
     });
   });
 
-  it('HEAD request to directory index', (done) => {
+  it('should handles HEAD request to directory index', (done) => {
     req.head('/webpack-dev-server').then(({ res }) => {
       expect(res.headers['content-type']).toEqual('text/html');
       expect(res.statusCode).toEqual(200);
@@ -95,28 +95,28 @@ describe('Routes', () => {
     });
   });
 
-  it('GET request to magic html', (done) => {
+  it('should handles GET request to magic html', (done) => {
     req.get('/main').then(({ res }) => {
       expect(res.statusCode).toEqual(200);
       done();
     });
   });
 
-  it('HEAD request to magic html', (done) => {
+  it('should handles HEAD request to magic html', (done) => {
     req.head('/main').then(({ res }) => {
       expect(res.statusCode).toEqual(200);
       done();
     });
   });
 
-  it('GET request to main chunk', (done) => {
+  it('should handles GET request to main chunk', (done) => {
     req.get('/main.js').then(({ res }) => {
       expect(res.statusCode).toEqual(200);
       done();
     });
   });
 
-  it('HEAD request to main chunk', (done) => {
+  it('should handles HEAD request to main chunk', (done) => {
     req.head('/main.js').then(({ res }) => {
       expect(res.statusCode).toEqual(200);
       done();