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