Provides support for the Karma TestRunner (formally Testacular).
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When running Karma against an artifact that is being used in a team development environment in Java-land, there are typically a few problems you encounter:

  • You have people on a variety of operating systems, so what browsers, ports and so forth are available to you are different between people even if the javascript tests are the same

  • Servlet 3 JARs - these are considerably better in that they allow you modularity in your Servlet container. But each jar may have a set of static resources located in /META-INF/resources - and Karma Runner takes care of those.

Version 2 supports Karma 0.12 and drops support for War Overlays.

What this plugin lets you do is specify a common configuration file for your Karma settings, let the plugin specify where the files needed for each overlay come from (if any) and also include personal overrides as necessary.

Apache Maven Central

The karma-runner plugin is now in Apache Maven Central and is currently version 2.1


  • Java 7 - no mucking around with obsolete versions of Java

  • Maven 3.0.4+ - its been out forever, really, you should be using it

  • Karma (I’m using 0.12+) and all its requirements (nodejs, npm, etc)

How it works

To support overlays, the plugin looks for war dependencies and extracts them into target/karma/overlay-artifact-id.

(it always deletes the directory first), so for example, these dependencies:

      <scope>test</scope>  <!-- this is a Servlet 3 jar -->

will be extracted into


It will make a variable


available with the directory the files were extracted to, but if there is a - in the artifact, it will be replaced with _ (to make a valid Java variable name), so you would get


added to the binding given to your template file.

A look in the tests show a sample karma file:

    files: [

Overriding Artifacts

This is an important part of debugging. You may get into situations where you want to ship your front end with your mock data, yet have the option to later only use it for testing (so you don’t get stuck in the functional testing loop). We separate the front-end into two artifacts - "user" and "user-test" (as an example) - these are then combined in another artifact (a war artifact). This means for initial customer demos, you can have "user-test" as a full dependency in "war", and a test dependendency in "user". When you have a real-backend, you can swap out the "user-test" for that backend in your "war" artifact.

This also happens when we are working on shared Angular directives and they have an impact on our current tests. Ensuring that our Karma is pointing to the latest source code (and not the released artifacts or installed snapshots) is incredibly useful and a productive use of time.

To point to a location on disk instead of having the plugin extract the contents of your jar/war file, you can provide a system property with the name:

mvn -Dkarma.common.javascript=../shared-test-resources/src/main/resources/META-INF/resources karma:voyeur

and this will override the extraction (which will not happen) if you are working with that project directly on disk and want Karma to have live updates from it. This can be a relative path but that karma-runner will turn it into an absolute path. The reason it does this is that the final karma-runner file gets created in the target directory.

Providing extra configuration

You can provide an extra configuration file that gets appended based on matching. This means you can replace any property that is already defined (as the file is javascript), and typically you would do this for browser support which tends to vary. It is also useful for headless Continuous Integration servers like Jenkins, Team City, and Bamboo.

The default file location is ${user.home}/.karma

And if it finds the line


it will insert that file ${user.home}/.karma/karma.local.js

A typical example of a Karma local file would be to change the browsers available on your machine. For example:

	  browsers: ['Chrome', 'Firefox', 'Safari']

Maven Configuration

     <nodeLocation>node</nodeLocation> <!-- The command needed to run node, wherever it may be ->
     <karmaLocation>karma</karma> <!-- The command needed to run karma, wherever it may be -->
     <templateFile>karma-template.cfg.js</templateFile> <!-- the file the plugin picks up and replaces stuff in -->
     <karmaFile>karma-runner.cfg.js</karmaFile> <!-- this is the file that gets generated, that Karma runs -->
     <karmaLocalisation>${user.home}/.karma</karmaLocalisation> <!-- where to find the local karma file -->

None of the configuration options are required, those listed are the defaults. The minimum configuration is:


I recommend you put this in your war or war-overlay functional parent. It will not fail if it cannot find the karma template, if it doesn’t find it, it just issues a warning and exits.

Running the plugin

The plugin is run from the command line with:


This puts Karma into a single run, no auto watch mode.



This puts Karma into its mode of auto watching for file updates and re-running tests.

Making the plugin part of your tests

If you wish to ensure that Karma gets run as part of your tests, you can include the karma-runner as an execution.



2.1 - support for Karma 0.12 and probably 0.10 and dropping support for War overlays (they are not tested for) 1.6 - fixes a path bug in Windows 1.5 - fixes a bug in the override path that prevented it from being used properly. Updated the documentation. 1.4 - first release to the public.