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 |