feat: remove support for running dart code in the browser (#3592)

As Dartium browser is no more, there are no browsers left, which support running Dart applications natively and therefore we can remove such support from Karma to reduce the maintenance effort.

BREAKING CHANGE: Using Karma to run Dart code in the browser is no longer supported. Use your favorite Dart-to-JS compiler instead.

`dart` file type has been removed without a replacement.

`customFileHandlers` DI token has been removed. Use [`middleware`](http://karma-runner.github.io/5.2/config/configuration-file.html#middleware) to achieve similar functionality.

`customScriptTypes` DI token has been removed. It had no effect, so no replacement is provided.

Author: devoto13

docs/config/02-files.md

@@ -31,7 +31,6 @@ Each pattern is either a simple string or an object with the following propertie
   * `css` - Include using `<link rel="stylesheet">` tag.
   * `html` - Include using [HTML Imports](https://developer.mozilla.org/en-US/docs/Web/Web_Components/HTML_Imports). Note that this feature is obsolete and does not work in the modern browsers. 
   * `js` - Include using `<script></script>` tag.
-  * `dart` - Include using `<script type="application/dart"></script>` tag. Note that this does not work in the modern browsers.
   * `module` - Include using `<script type="module"></script>` tag.
   * `dom` - Inline content of the file in the page. This can be used, for example, to test components combining HTML and JS.
 * **Description.** The type determines the mechanism for including the file.

docs/dev/05-plugins.md

@@ -34,7 +34,7 @@ A preprocessor is a function that accepts three arguments (`content`, `file`, an
 - user NPM keywords `karma-plugin`, `karma-preprocessor`
 
 ## Crazier stuff
-Karma is assembled by Dependency Injection and a plugin is just an additional DI module (see [node-di] for more), that can be loaded by Karma. Therefore, it can ask for pretty much any Karma component and interact with it. There are a couple of plugins that do more interesting stuff like this, check out [karma-closure], [karma-intellij], [karma-dart].
+Karma is assembled by Dependency Injection and a plugin is just an additional DI module (see [node-di] for more), that can be loaded by Karma. Therefore, it can ask for pretty much any Karma component and interact with it. There are a couple of plugins that do more interesting stuff like this, check out [karma-closure], [karma-intellij].
 
 
 [karma-jasmine]: https://github.com/karma-runner/karma-jasmine
@@ -49,7 +49,6 @@ Karma is assembled by Dependency Injection and a plugin is just an additional DI
 [karma-ng-html2js-preprocessor]: https://github.com/karma-runner/karma-ng-html2js-preprocessor
 [karma-closure]: https://github.com/karma-runner/karma-closure
 [karma-intellij]: https://github.com/karma-runner/karma-intellij
-[karma-dart]: https://github.com/karma-runner/karma-dart
 [node-di]: https://github.com/vojtajina/node-di
 [karma-material-reporter]: https://github.com/ameerthehacker/karma-material-reporter
 

lib/middleware/karma.js

@@ -20,14 +20,12 @@ const common = require('./common')
 const VERSION = require('../constants').VERSION
 const SCRIPT_TYPE = {
   js: 'text/javascript',
-  dart: 'application/dart',
   module: 'module'
 }
 const FILE_TYPES = [
   'css',
   'html',
   'js',
-  'dart',
   'module',
   'dom'
 ]

lib/server.js

@@ -82,10 +82,6 @@ class Server extends KarmaEventEmitter {
       filesPromise: ['factory', createFilesPromise],
       socketServer: ['factory', createSocketIoServer],
       executor: ['factory', Executor.factory],
-      // TODO(vojta): remove
-      customFileHandlers: ['value', []],
-      // TODO(vojta): remove, once karma-dart does not rely on it
-      customScriptTypes: ['value', []],
       reporter: ['factory', reporter.createReporters],
       capturedBrowsers: ['factory', BrowserCollection.factory],
       args: ['value', {}],

lib/web-server.js

@@ -16,17 +16,6 @@ const proxyMiddleware = require('./middleware/proxy')
 
 const log = require('./logger').create('web-server')
 
-function createCustomHandler (customFileHandlers, config) {
-  return function (request, response, next) {
-    const handler = customFileHandlers.find((handler) => handler.urlRegex.test(request.url))
-    return handler
-      ? handler.handler(request, response, 'fake/static', 'fake/adapter', config.basePath, 'fake/root')
-      : next()
-  }
-}
-
-createCustomHandler.$inject = ['customFileHandlers', 'config']
-
 function createFilesPromise (emitter, fileList) {
   // Set an empty list of files to avoid race issues with
   // file_list_modified not having been emitted yet
@@ -69,9 +58,6 @@ function createWebServer (injector, config) {
   handler.use(injector.invoke(sourceFilesMiddleware.create))
   // TODO(vojta): extract the proxy into a plugin
   handler.use(proxyMiddlewareInstance)
-  // TODO(vojta): remove, this is only here because of karma-dart
-  // we need a better way of custom handlers
-  handler.use(injector.invoke(createCustomHandler))
 
   if (config.middleware) {
     config.middleware.forEach((middleware) => handler.use(injector.get('middleware:' + middleware)))

test/unit/middleware/karma.spec.js

@@ -202,12 +202,12 @@ describe('middleware.karma', () => {
   it('should serve context.html with replaced script tags', (done) => {
     includedFiles([
       new MockFile('/first.js', 'sha123'),
-      new MockFile('/second.dart', 'sha456')
+      new MockFile('/second.js', 'sha456')
     ])
 
     response.once('end', () => {
       expect(nextSpy).not.to.have.been.called
-      expect(response).to.beServedAs(200, 'CONTEXT\n<script type="text/javascript" src="/__proxy__/__karma__/absolute/first.js?sha123" crossorigin="anonymous"></script>\n<script type="application/dart" src="/__proxy__/__karma__/absolute/second.dart?sha456" crossorigin="anonymous"></script>')
+      expect(response).to.beServedAs(200, 'CONTEXT\n<script type="text/javascript" src="/__proxy__/__karma__/absolute/first.js?sha123" crossorigin="anonymous"></script>\n<script type="text/javascript" src="/__proxy__/__karma__/absolute/second.js?sha456" crossorigin="anonymous"></script>')
       done()
     })
 

test/unit/web-server.spec.js

@@ -31,7 +31,7 @@ describe('web-server', () => {
   // NOTE(vojta): only loading once, to speed things up
   // this relies on the fact that none of these tests mutate fs
   const m = mocks.loadFile(path.join(__dirname, '/../../lib/web-server.js'), _mocks, _globals)
-  let customFileHandlers = server = emitter = null
+  server = emitter = null
   let beforeMiddlewareActive = false
   let middlewareActive = false
   const servedFiles = (files) => {
@@ -40,7 +40,6 @@ describe('web-server', () => {
 
   describe('request', () => {
     beforeEach(() => {
-      customFileHandlers = []
       emitter = new EventEmitter()
       const config = {
         basePath: '/base/path',
@@ -57,7 +56,6 @@ describe('web-server', () => {
 
       const injector = new di.Injector([{
         config: ['value', config],
-        customFileHandlers: ['value', customFileHandlers],
         emitter: ['value', emitter],
         fileList: ['value', { files: { served: [], included: [] } }],
         filesPromise: ['factory', m.createFilesPromise],
@@ -182,23 +180,6 @@ describe('web-server', () => {
         })
     })
 
-    it('should load custom handlers', () => {
-      servedFiles(new Set())
-
-      // TODO(vojta): change this, only keeping because karma-dart is relying on it
-      customFileHandlers.push({
-        urlRegex: /\/some\/weird/,
-        handler (request, response, staticFolder, adapterFolder, baseFolder, urlRoot) {
-          response.writeHead(222)
-          response.end('CONTENT')
-        }
-      })
-
-      return request(server)
-        .get('/some/weird/url')
-        .expect(222, 'CONTENT')
-    })
-
     it('should serve 404 for non-existing files', () => {
       servedFiles(new Set())
 
@@ -215,7 +196,6 @@ describe('web-server', () => {
         cert: fs.readFileSync(path.join(__dirname, '/certificates/server.crt'))
       }
 
-      customFileHandlers = []
       emitter = new EventEmitter()
 
       const injector = new di.Injector([{
@@ -226,7 +206,6 @@ describe('web-server', () => {
           httpsServerOptions: credentials,
           client: { useIframe: true, useSingleWindow: false }
         }],
-        customFileHandlers: ['value', customFileHandlers],
         emitter: ['value', emitter],
         fileList: ['value', { files: { served: [], included: [] } }],
         filesPromise: ['factory', m.createFilesPromise],
@@ -265,12 +244,10 @@ describe('web-server', () => {
         cert: fs.readFileSync(path.join(__dirname, '/certificates/server.crt'))
       }
 
-      customFileHandlers = []
       emitter = new EventEmitter()
 
       const injector = new di.Injector([{
         config: ['value', { basePath: '/base/path', urlRoot: '/', httpModule: http2, protocol: 'https:', httpsServerOptions: credentials }],
-        customFileHandlers: ['value', customFileHandlers],
         emitter: ['value', emitter],
         fileList: ['value', { files: { served: [], included: [] } }],
         filesPromise: ['factory', m.createFilesPromise],