fix: check existence of res.getHeader and set the correct Content-T…

…ype (#385)

lib/middleware.js

@@ -103,7 +103,7 @@ module.exports = function wrapper(context) {
           contentType += '; charset=UTF-8';
         }
 
-        if (!res.getHeader('Content-Type')) {
+        if (!res.getHeader || !res.getHeader('Content-Type')) {
           res.setHeader('Content-Type', contentType);
         }
 

test/mock-express/index.js

@@ -0,0 +1,42 @@
+'use strict';
+
+const mockRequest = (options = {}) =>
+  Object.assign(
+    {
+      body: {},
+      cookies: {},
+      query: {},
+      params: {},
+      get: jest.fn(),
+    },
+    options
+  );
+
+const mockResponse = (options = {}) => {
+  const res = Object.assign(
+    {
+      cookie: jest.fn(),
+      clearCookie: jest.fn(),
+      download: jest.fn(),
+      format: jest.fn(),
+      json: jest.fn(),
+      jsonp: jest.fn(),
+      send: jest.fn(),
+      sendFile: jest.fn(),
+      sendStatus: jest.fn(),
+      setHeader: jest.fn(),
+      redirect: jest.fn(),
+      render: jest.fn(),
+      end: jest.fn(),
+      set: jest.fn(),
+      type: jest.fn(),
+      get: jest.fn(),
+    },
+    options
+  );
+  res.status = jest.fn(() => res);
+  res.vary = jest.fn(() => res);
+  return res;
+};
+
+module.exports = { mockRequest, mockResponse };

test/server.test.js

@@ -9,6 +9,8 @@ const request = require('supertest');
 
 const middleware = require('../');
 
+const { mockRequest, mockResponse } = require('./mock-express');
+
 const webpackConfig = require('./fixtures/server-test/webpack.config');
 const webpackMultiConfig = require('./fixtures/server-test/webpack.array.config');
 const webpackQuerystringConfig = require('./fixtures/server-test/webpack.querystring.config');
@@ -311,6 +313,35 @@ describe('Server', () => {
     });
   });
 
+  /**
+   * ref: #385, for that koa-webpack@4.x doesn't pass in res.getHeader method.
+   */
+  describe('Should work when res.getHeader is undefined', () => {
+    it('should not throw error', (done) => {
+      const req = mockRequest({
+        url: '/',
+        method: 'GET',
+        headers: {
+          Range: 'bytes=6000-',
+        },
+      });
+
+      const res = mockResponse({
+        getHeader: undefined,
+        setHeader: jest.fn(),
+      });
+
+      const compiler = webpack(webpackConfig);
+      instance = middleware(compiler, {
+        stats: 'errors-only',
+        logLevel,
+      });
+
+      instance(req, res, jest.fn()).then(done);
+    });
+    afterAll(close);
+  });
+
   describe('custom mimeTypes', () => {
     beforeAll((done) => {
       app = express();