feat(config): add support for ES modules

- Add support for ES modules via `esModule` property in file config object

docs/config/02-files.md

@@ -52,6 +52,11 @@ Each pattern is either a simple string or an object with four properties:
 * **Default.** `true`
 * **Description.** Should the files be served by Karma's webserver?
 
+### `esModule`
+* **Type.** Boolean
+* **Default.** `false`
+* **Description.** Should the files be loaded as ECMAScript modules?
+
 ### `nocache`
 * **Type.** Boolean
 * **Default.** `false`

lib/config.js

@@ -30,11 +30,12 @@ try {
   TYPE_SCRIPT_AVAILABLE = true
 } catch (e) {}
 
-var Pattern = function (pattern, served, included, watched, nocache) {
+var Pattern = function (pattern, served, included, watched, nocache, esModule) {
   this.pattern = pattern
   this.served = helper.isDefined(served) ? served : true
   this.included = helper.isDefined(included) ? included : true
   this.watched = helper.isDefined(watched) ? watched : true
+  this.esModule = helper.isDefined(esModule) ? esModule : false
   this.nocache = helper.isDefined(nocache) ? nocache : false
   this.weight = helper.mmPatternWeight(pattern)
 }
@@ -44,7 +45,7 @@ Pattern.prototype.compare = function (other) {
 }
 
 var UrlPattern = function (url) {
-  Pattern.call(this, url, false, true, false, false)
+  Pattern.call(this, url, false, true, false, false, false)
 }
 
 var createPatternObject = function (pattern) {
@@ -61,7 +62,8 @@ var createPatternObject = function (pattern) {
           pattern.served,
           pattern.included,
           pattern.watched,
-          pattern.nocache)
+          pattern.nocache,
+          pattern.esModule)
     }
 
     log.warn('Invalid pattern %s!\n\tObject is missing "pattern" property.', pattern)

lib/file-list.js

@@ -183,7 +183,8 @@ List.prototype._refresh = function () {
 
       var mtime = mg.statCache[path].mtime
       var doNotCache = patternObject.nocache
-      var file = new File(path, mtime, doNotCache)
+      var esModule = patternObject.esModule
+      var file = new File(path, mtime, doNotCache, esModule)
 
       if (file.doNotCache) {
         log.debug('Not preprocessing "%s" due to nocache')

lib/file.js

@@ -9,7 +9,7 @@
 var _ = require('lodash')
 
 // Constructor
-var File = function (path, mtime, doNotCache) {
+var File = function (path, mtime, doNotCache, esModule) {
   // used for serving (processed path, eg some/file.coffee -> some/file.coffee.js)
   this.path = path
 
@@ -23,6 +23,7 @@ var File = function (path, mtime, doNotCache) {
   this.isUrl = false
 
   this.doNotCache = _.isUndefined(doNotCache) ? false : doNotCache
+  this.esModule = esModule
 }
 
 File.prototype.toString = function () {

lib/middleware/karma.js

@@ -178,6 +178,7 @@ var createKarmaMiddleware = function (
             var file = files.included[i]
             var filePath = file.path
             var fileExt = path.extname(filePath)
+            var esModule = fileExt.endsWith('js') && file.esModule
 
             if (!files.included.hasOwnProperty(i)) {
               continue
@@ -204,7 +205,7 @@ var createKarmaMiddleware = function (
             }
 
             // The script tag to be placed
-            var scriptType = (SCRIPT_TYPE[fileExt] || 'text/javascript')
+            var scriptType = esModule ? 'module' : (SCRIPT_TYPE[fileExt] || 'text/javascript')
 
             // In case there is a JavaScript version specified and this is a Firefox browser
             if (jsVersion && jsVersion > 0 && isFirefox(request)) {

test/e2e/module-types.feature

@@ -0,0 +1,25 @@
+Feature: ES Modules
+  In order to use Karma
+  As a person who wants to write great tests
+  I want to use different script types with Karma.
+
+  Scenario: Simple middleware
+    Given a configuration with:
+      """
+      files = [
+        { pattern: 'modules/plus.js', esModule: false },
+        { pattern: 'modules/minus.mjs', esModule: true },
+        'modules/test.js'
+      ];
+      browsers = ['Firefox'];
+      plugins = [
+        'karma-jasmine',
+        'karma-firefox-launcher'
+      ];
+      """
+    When I start Karma
+    Then it passes with:
+      """
+      .
+      Firefox
+      """

test/e2e/support/modules/minus.mjs

@@ -0,0 +1,15 @@
+// Some code under test
+function minus (a, b) {
+  return a - b
+}
+
+describe('minus', function () {
+  it('should pass', function () {
+    expect(true).toBe(true)
+  })
+
+  it('should work', function () {
+    expect(minus(3, 2)).toBe(1)
+  })
+})
+

test/e2e/support/modules/plus.js

@@ -0,0 +1,5 @@
+/* eslint-disable no-unused-vars */
+// Some code under test
+function plus (a, b) {
+  return a + b
+}

test/e2e/support/modules/test.js

@@ -0,0 +1,10 @@
+/* globals plus */
+describe('plus', function () {
+  it('should pass', function () {
+    expect(true).toBe(true)
+  })
+
+  it('should work', function () {
+    expect(plus(1, 2)).toBe(3)
+  })
+})