feat(bundler): add a bundler layer

The input config supplies 'patterns' which FileList expands into Files.
These files are preprocessed and then 'file-list-modified' is fired.
The event offers a pair of file lists, {included, served}.
The bundle layer maps this pair to a new pair where fewer files are included.
By default the bundler copies the inputs to outputs.

Fixes #3633

lib/middleware/karma.js

@@ -59,7 +59,7 @@ function getXUACompatibleUrl (url) {
 }
 
 function createKarmaMiddleware (
-  currentFiles,
+  currentWebFiles,
   serveStaticFile,
   serveFile,
   injector,
@@ -132,7 +132,6 @@ function createKarmaMiddleware (
     const isRequestingDebugFile = requestUrl === '/debug.html'
     const isRequestingClientContextFile = requestUrl === '/client_with_context.html'
     if (isRequestingContextFile || isRequestingDebugFile || isRequestingClientContextFile) {
-      const files = currentFiles.files
       let fileServer
       let requestedFileUrl
       log.debug('custom files', customContextFile, customDebugFile, customClientContextFile)
@@ -157,7 +156,7 @@ function createKarmaMiddleware (
       fileServer(requestedFileUrl, requestedRangeHeader, response, function (data) {
         common.setNoCacheHeaders(response)
         const scriptTags = []
-        for (const file of files.included) {
+        for (const file of currentWebFiles.included) {
           let filePath = file.path
           const fileType = file.type || file.detectType()
 
@@ -212,7 +211,7 @@ function createKarmaMiddleware (
           }
         }
 
-        const mappings = data.includes('%MAPPINGS%') ? files.served.map((file) => {
+        const mappings = data.includes('%MAPPINGS%') ? currentWebFiles.served.map((file) => {
           const filePath = filePathToUrlPath(file.path, basePath, urlRoot, proxyPath)
             .replace(/\\/g, '\\\\') // Windows paths contain backslashes and generate bad IDs if not escaped
             .replace(/'/g, '\\\'') // Escape single quotes - double quotes should not be allowed!
@@ -228,11 +227,10 @@ function createKarmaMiddleware (
           .replace('\n%X_UA_COMPATIBLE%', getXUACompatibleMetaElement(request.url))
       })
     } else if (requestUrl === '/context.json') {
-      const files = currentFiles.files
       common.setNoCacheHeaders(response)
       response.writeHead(200)
       response.end(JSON.stringify({
-        files: files.included.map((file) => filePathToUrlPath(file.path + '?' + file.sha, basePath, urlRoot, proxyPath))
+        files: currentWebFiles.included.map((file) => filePathToUrlPath(file.path + '?' + file.sha, basePath, urlRoot, proxyPath))
       }))
     } else {
       next()
@@ -241,7 +239,7 @@ function createKarmaMiddleware (
 }
 
 createKarmaMiddleware.$inject = [
-  'currentFiles',
+  'currentWebFiles',
   'serveStaticFile',
   'serveFile',
   'injector',

lib/middleware/source_files.js

@@ -18,7 +18,7 @@ function composeUrl (url, basePath, urlRoot) {
 }
 
 // Source Files middleware is responsible for serving all the source files under the test.
-function createSourceFilesMiddleware (currentFiles, serveFile, basePath, urlRoot) {
+function createSourceFilesMiddleware (currentWebFiles, serveFile, basePath, urlRoot) {
   return function (request, response, next) {
     const requestedFilePath = composeUrl(request.url, basePath, urlRoot)
     // When a path contains HTML-encoded characters (e.g %2F used by Jenkins for branches with /)
@@ -29,9 +29,8 @@ function createSourceFilesMiddleware (currentFiles, serveFile, basePath, urlRoot
     log.debug(`Requesting ${request.url}`)
     log.debug(`Fetching ${requestedFilePath}`)
 
-    const files = currentFiles.files
     // TODO(vojta): change served to be a map rather then an array
-    const file = findByPath(files.served, requestedFilePath) || findByPath(files.served, requestedFilePathUnescaped)
+    const file = findByPath(currentWebFiles.served, requestedFilePath) || findByPath(currentWebFiles.served, requestedFilePathUnescaped)
     const rangeHeader = request.headers.range
 
     if (file) {
@@ -60,7 +59,7 @@ function createSourceFilesMiddleware (currentFiles, serveFile, basePath, urlRoot
 }
 
 createSourceFilesMiddleware.$inject = [
-  'currentFiles', 'serveFile', 'config.basePath', 'config.urlRoot'
+  'currentWebFiles', 'serveFile', 'config.basePath', 'config.urlRoot'
 ]
 
 exports.create = createSourceFilesMiddleware

lib/server.js

@@ -19,8 +19,9 @@ const plugin = require('./plugin')
 
 const createServeFile = require('./web-server').createServeFile
 const createServeStaticFile = require('./web-server').createServeStaticFile
-const createCurrentFiles = require('./web-server').createCurrentFiles
+const createFilesPromise = require('./web-server').createFilesPromise
 const createWebServer = require('./web-server').createWebServer
+const createWebFiles = require('./web-files').createWebFiles
 const preprocessor = require('./preprocessor')
 const Launcher = require('./launcher').Launcher
 const FileList = require('./file-list')
@@ -82,7 +83,10 @@ class Server extends KarmaEventEmitter {
       webServer: ['factory', createWebServer],
       serveFile: ['factory', createServeFile],
       serveStaticFile: ['factory', createServeStaticFile],
-      currentFiles: ['factory', createCurrentFiles],
+      // Obsolete, do not use
+      filesPromise: ['factory', createFilesPromise],
+      // The files to be included/served to browser for test
+      currentWebFiles: ['factory', createWebFiles],
       socketServer: ['factory', createSocketIoServer],
       executor: ['factory', Executor.factory],
       // TODO: Deprecated. Remove in the next major
@@ -343,8 +347,8 @@ class Server extends KarmaEventEmitter {
     }
 
     if (config.autoWatch) {
-      this.on('file_list_modified', () => {
-        this.log.debug('List of files has changed, trying to execute')
+      this.on('web_files_modified', () => {
+        this.log.debug('List of included/served files has changed, trying to execute')
         if (config.restartOnFileChange) {
           socketServer.sockets.emit('stop')
         }

lib/web-files.js

@@ -0,0 +1,45 @@
+/**
+  Container class for the files included in context.html and served upon
+  request. Two instances fit into the files pipeline:
+    1. The result from FileList.files, the list of preprocessed input files.
+    2. The result of bundling #1 stored in currentWebFiles
+*/
+class WebFiles {
+  constructor (included, served) {
+    this.included = [...included]
+    this.served = [...served]
+  }
+}
+
+let currentWebFiles = new WebFiles([], [])
+
+function noOpBundler (webFiles) {
+  return new WebFiles(webFiles.included, webFiles.served)
+}
+
+let bundler = noOpBundler
+
+function registerBundler (emitter) {
+  emitter.on('file_list_modified', (modifiedWebFiles) => {
+    // Any bundler is expected to return a WebFiles object.
+    // For sourcemap support, //# sourceUrl in the bundler result should
+    // point back to the input files.
+    currentWebFiles = Object.assign(currentWebFiles, bundler(modifiedWebFiles))
+    emitter.emit('web_files_modified', currentWebFiles)
+  })
+}
+
+function createWebFiles (configBundler, instantiatePlugin, emitter) {
+  if (configBundler) {
+    bundler = instantiatePlugin('bundler', configBundler)
+  }
+  registerBundler(emitter)
+  return currentWebFiles
+}
+
+createWebFiles.$inject = ['config.bundler', 'instantiatePlugin', 'emitter']
+
+module.exports = {
+  createWebFiles,
+  WebFiles
+}

lib/web-server.js

@@ -46,13 +46,6 @@ function createFilesPromise (emitter, fileList) {
       return Promise.resolve(files).then(...args)
     }
   }
-
-function createCurrentFiles (emitter, fileList) {
-  const currentFileList = { files: fileList.files }
-  emitter.on('file_list_modified', (modifiedFiles) => {
-    currentFileList.files = modifiedFiles
-  })
-  return currentFileList
 }
 
 function createServeStaticFile (config) {
@@ -121,5 +114,5 @@ module.exports = {
   createWebServer,
   createServeFile,
   createServeStaticFile,
-  createCurrentFiles
+  createFilesPromise
 }