Karma

September 30, 2024

What is Karma?

Karma is a Javascript test runner that allows you to execute your tests in real browsers, ensuring that your code works as expected across different environments. Karma can be used for both unit testing, meaning it tests parts of a codebase in isolation, as well as integration testing where the parts are combined and tested to see how they work together.

As Karma only runs the tests, it is often used in conjunction with testing libraries such as Mocha, Jasmin, and Chai.

Enabling XML Output

Karma can be configured to produce JUnit XML output by adding the karma-junit-reporter package to your codebase.

1npm install --save-dev karma-junit-reporter

Also add the junit reporter to your karma config file. ex:

1reporters: ['progress','junit'],

Now run Karma from the command line or inside your CI system as:

1karma start <your-config.cjs>

Test Suite naming

The XML output can be customized by adding a junitReporter section to your Karma config file. You can set the name of the test suite using the suite attribute. You can customize the output directory and output file name using the outputDir and outputFile attributes. Names and classnames can be customized by providing formatter functions. Ex:

1junitReporter:{
2 outputDir: 'test-output',
3 outputFile:'karma-output.xml',
4 suite:'my-test-suite',
5 useBrowserName:false,
6 // function (browser, result) to customize the name attribute in xml testcase element
7 nameFormatter: function(browser, result) { return "cool-name"},
8 // function (browser, result) to customize the classname attribute in xml testcase element
9 // classNameFormatter: undefined,
10 classNameFormatter: function(browser,result) { return "cool-class-name" }
11},

Handling Retries

By default, when the browser crashes Karma will try to load the browser again up to two times. You can increase this using the retryLimit setting in the config file.

Karma will retry unit tests in the browser continuously. To run the tests only once use the --single-run command line argument or set the singleRun attribute to false in the config file. See the Karma Config File documentation for more details.

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