karma-jasmine

What is karma-jasmine?

The karma-jasmine npm package is a plugin for the Karma test runner that allows you to run and write tests using the Jasmine framework. Jasmine is a behavior-driven development framework for testing JavaScript code. Karma serves as a test environment that can run tests in multiple real browsers, which is useful for integration and unit testing.

What are karma-jasmine's main functionalities?

Testing Framework Integration

Integrates Jasmine with Karma to run tests written in Jasmine style within a browser environment.

module.exports = function(config) {
  config.set({
    frameworks: ['jasmine'],
    files: [
      'src/**/*.js',
      'test/**/*.spec.js'
    ],
    browsers: ['Chrome'],
    singleRun: true
  });
};

Describe and It Blocks

Allows writing test suites and specifications using Jasmine's global functions 'describe' and 'it'.

describe('A suite', function() {
  it('contains a spec with an expectation', function() {
    expect(true).toBe(true);
  });
});

Matchers

Provides a rich set of matchers (assertions) that can be used to test expected outcomes.

describe('Matchers', function() {
  it('allows for using Jasmine matchers', function() {
    expect(1 + 2).toEqual(3);
    expect(true).toBe(true);
    expect([1, 2, 3]).toContain(2);
  });
});

Spies

Supports Jasmine spies to track calls to functions and their arguments.

describe('A spy', function() {
  var foo, bar = null;

  beforeEach(function() {
    foo = {
      setBar: function(value) {
        bar = value;
      }
    };

    spyOn(foo, 'setBar');

    foo.setBar(123);
    foo.setBar(456, 'another param');
  });

  it('tracks that the spy was called', function() {
    expect(foo.setBar).toHaveBeenCalled();
  });
});

Asynchronous Support

Handles asynchronous operations in tests with Jasmine's done function.

describe('Async code', function() {
  var value;
  beforeEach(function(done) {
    setTimeout(function() {
      value = 0;
      done();
    }, 1);
  });

  it('should support async execution of test preparation and expectations', function(done) {
    value++;
    expect(value).toBeGreaterThan(0);
    done();
  });
});

Other packages similar to karma-jasmine

mocha

Mocha is a feature-rich JavaScript test framework running on Node.js and in the browser, making asynchronous testing simple. It's often compared to Jasmine, as both are behavior-driven development frameworks, but Mocha is more flexible in terms of assertion libraries, mock/stub utilities, and reporting.

jest

Jest is a delightful JavaScript Testing Framework with a focus on simplicity. It works out of the box for any React project and is often favored for its snapshot testing feature. Jest provides its own assertion library and test runner, and it can be used as an alternative to the Karma-Jasmine setup.

chai

Chai is an assertion library for node and the browser that can be delightfully paired with any javascript testing framework. It's often used with Mocha as an alternative to Jasmine's assertion syntax, offering both BDD and TDD assertion styles.

ava

AVA is a test runner for Node.js with a concise API, detailed error output, and process isolation that lets you develop with confidence. It differs from Karma-Jasmine in that it's designed to run tests concurrently, which can improve performance for large test suites.

tape

Tape is a tap-producing test harness for node and browsers requiring minimal configuration. Unlike Karma-Jasmine, Tape is more simplistic and doesn't need a DOM, making it suitable for Node.js testing, but less so for browser-specific tests.

README

karma-jasmine

Adapter for the Jasmine testing framework.

Installation

npm install karma-jasmine --save-dev

Configuration

// karma.conf.js
module.exports = function(config) {
  config.set({
    frameworks: ['jasmine'],
    files: [
      '*.js'
    ]
  })
}

If you want to run only some tests whose name match a given pattern you can do this in the following way

$ karma start &
$ karma run -- --grep=<pattern>

where pattern is either a string (e.g --grep=#slow runs tests containing "#slow") or a Regex (e.g --grep=/^(?!.*#slow).*$/ runs tests not containing "#slow").

You can also pass it to karma.config.js:

module.exports = function(config) {
  config.set({
    // ...
    client: {
      args: ['--grep', '<pattern>'],
      // ...
    }
  })
}

If you want to pass configuration options directly to jasmine you can do this in the following way

module.exports = function(config) {
  config.set({
    client: {
      jasmine: {
        random: true,
        seed: '4321',
        oneFailurePerSpec: true,
        failFast: true,
        timeoutInterval: 1000
      }
    }
  })
}

Debug by URL

Failing tests print a debug URL with ?spec=. Use it with --no_single_run and paste it into your browser to focus on a single failing test.

Sharding

By setting config.client.shardIndex and config.client.totalShards, you can run a subset of the full set of specs. Complete sharding support needs to be done in the process that calls karma, and would need to support test result integration across shards.

Custom spec filter

Providing a custom spec filter is also supported.

Example:

// Users are able to set a custom specFilter themselves

jasmine.getEnv().configure({
  specFilter: function (spec) {
    return spec.getFullName() === 'spec that succeeds'
  }
})

describe('spec', () => {
  it('that fails', () => {
    fail('This spec should not run!')
  })

  it('that succeeds', () => {
    expect(1).toBe(1)
  })
})

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For more information on Karma see the homepage.