Refactor webpack-dev-server middleware application logic

lib/Server.js

@@ -552,6 +552,21 @@ class Server {
           searchParams.set("password", webSocketURL.password);
         }
 
+              // Initialize an array to keep track of applied middleware
+                  const appliedMiddleware = [];
+
+                  // Function to apply middleware only once
+                  function applyMiddlewareOnce(app, middleware) {
+                    // Check if the middleware has already been applied
+                    if (!appliedMiddleware.includes(middleware)) {
+                      // Apply the middleware
+                      app.use(middleware);
+
+                      // Add the middleware to the applied middleware array
+                      appliedMiddleware.push(middleware);
+                    }
+                  }
+
         /** @type {string} */
         let hostname;
 

test/server/open-option.test.js

@@ -959,3 +959,42 @@ describe('"open" option', () => {
     loggerWarnSpy.mockRestore();
   });
 });
+
+// applyMiddlewareOnce-test
+
+const { applyMiddlewareOnce } = require('../../lib/Server');
+
+describe('applyMiddlewareOnce', () => {
+  let app;
+
+  beforeEach(() => {
+    // Mock Express app
+    app = {
+      use: jest.fn()
+    };
+  });
+
+  afterEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it('should apply middleware only once', () => {
+    const middlewareFunction = jest.fn();
+    applyMiddlewareOnce(app, middlewareFunction);
+    applyMiddlewareOnce(app, middlewareFunction);
+
+    expect(app.use).toHaveBeenCalledTimes(1);
+    expect(app.use).toHaveBeenCalledWith(middlewareFunction);
+  });
+
+  it('should apply different middleware functions separately', () => {
+    const middlewareFunction1 = jest.fn();
+    const middlewareFunction2 = jest.fn();
+    applyMiddlewareOnce(app, middlewareFunction1);
+    applyMiddlewareOnce(app, middlewareFunction2);
+
+    expect(app.use).toHaveBeenCalledTimes(2);
+    expect(app.use).toHaveBeenCalledWith(middlewareFunction1);
+    expect(app.use).toHaveBeenCalledWith(middlewareFunction2);
+  });
+});

test/server/proxy-option.test.js

@@ -1035,3 +1035,43 @@ describe("proxy option", () => {
     });
   });
 });
+
+
+// applyMiddlewareOnce-test
+
+const { applyMiddlewareOnce } = require('../../lib/Server');
+
+describe('applyMiddlewareOnce', () => {
+  let app;
+
+  beforeEach(() => {
+    // Mock Express app
+    app = {
+      use: jest.fn()
+    };
+  });
+
+  afterEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it('should apply middleware only once', () => {
+    const middlewareFunction = jest.fn();
+    applyMiddlewareOnce(app, middlewareFunction);
+    applyMiddlewareOnce(app, middlewareFunction);
+
+    expect(app.use).toHaveBeenCalledTimes(1);
+    expect(app.use).toHaveBeenCalledWith(middlewareFunction);
+  });
+
+  it('should apply different middleware functions separately', () => {
+    const middlewareFunction1 = jest.fn();
+    const middlewareFunction2 = jest.fn();
+    applyMiddlewareOnce(app, middlewareFunction1);
+    applyMiddlewareOnce(app, middlewareFunction2);
+
+    expect(app.use).toHaveBeenCalledTimes(2);
+    expect(app.use).toHaveBeenCalledWith(middlewareFunction1);
+    expect(app.use).toHaveBeenCalledWith(middlewareFunction2);
+  });
+});