Add a karma:watch command

CHANGELOG

@@ -47,6 +47,7 @@ Motions:
 - Show motion identifier in (current) list of speakers [#3442]
 - Added navigation between single motions [#3459].
 - Improved the multiselect state filter [#3459]. 
+- Added karma:watch command [#3466].
 
 Elections:
 - Added pagination for list view [#3393].

DEVELOPMENT.rst

@@ -139,6 +139,9 @@ Run client tests by starting karma::
 
     $ yarn run karma
 
+Watch for file changes and run the tests automatically after each change::
+
+    $ yarn run karma:watch
 
 OpenSlides in big mode
 ======================

package.json

@@ -3,7 +3,8 @@
   "private": true,
   "scripts": {
     "prepublish": "bower install && gulp",
-    "karma": "karma start tests/karma/karma.conf.js"
+    "karma": "karma start tests/karma/karma.conf.js",
+    "karma:watch": "karma start tests/karma/karma.conf.js --single-run=false"
   },
   "devDependencies": {
     "angular-mocks": "~1.5.11",