Karma Testing Skill

Core Patterns

karma.conf.js

module.exports = function(config) {
  config.set({
    basePath: '',
    frameworks: ['jasmine'],
    files: [
      'src/**/*.js',
      'test/**/*.spec.js'
    ],
    preprocessors: {
      'src/**/*.js': ['coverage']
    },
    reporters: ['progress', 'coverage'],
    coverageReporter: {
      type: 'html',
      dir: 'coverage/'
    },
    port: 9876,
    colors: true,
    logLevel: config.LOG_INFO,
    autoWatch: true,
    browsers: ['Chrome', 'Firefox'],
    singleRun: false,
    concurrency: Infinity,

    // LambdaTest cloud browsers
    customLaunchers: {
      ChromeLT: {
        base: 'WebDriver',
        config: {
          hostname: 'hub.lambdatest.com',
          port: 80
        },
        browserName: 'Chrome',
        version: 'latest',
        name: 'Karma Test',
        tunnel: true,
        user: process.env.LT_USERNAME,
        accessKey: process.env.LT_ACCESS_KEY
      }
    }
  });
};

Test with Jasmine Framework

describe('StringUtils', () => {
  it('should capitalize first letter', () => {
    expect(StringUtils.capitalize('hello')).toBe('Hello');
  });

  it('should handle empty string', () => {
    expect(StringUtils.capitalize('')).toBe('');
  });
});

Angular Integration

// karma.conf.js for Angular
frameworks: ['jasmine', '@angular-devkit/build-angular'],
plugins: [
  require('karma-jasmine'),
  require('karma-chrome-launcher'),
  require('karma-coverage'),
  require('@angular-devkit/build-angular/plugins/karma')
],

Setup: npm install karma karma-jasmine karma-chrome-launcher karma-coverage --save-dev

Run: npx karma start or npx karma start --single-run

Init: npx karma init karma.conf.js

Deep Patterns

See reference/playbook.md for production-grade patterns:

| Section | What You Get | |---------|-------------| | §1 Production Configuration | Full karma.conf.js with coverage thresholds, reporters, CI launchers | | §2 Component Testing | Service mocking, DOM interaction, form validation patterns | | §3 HTTP Service Testing | HttpTestingController, error handling, retry testing | | §4 Directive & Pipe Testing | Host component pattern, custom pipes with edge cases | | §5 RxJS & Async Patterns | debounceTime, switchMap cancellation, subscription cleanup | | §6 Router & NgRx Testing | RouterTestingModule, MockStore, selector overrides | | §7 LambdaTest Integration | Cloud browser configuration for cross-browser testing | | §8 CI/CD Integration | GitHub Actions with coverage, test reporting | | §9 Debugging Table | 12 common problems with causes and fixes | | §10 Best Practices | 14-item checklist for production Angular testing |