Why is the Karma configuration file exclude option is not working?

Question

I have two spec files in my sample Angular app. The spec files names are src/app/app.component.spec.ts & src/app/app.component-two.spec.ts. I want to run only the tests in file src/app/app.component.spec.ts. So, I added the other file as exclude in the karma.conf.js file (pasted below), still the tests mentioned in the exclude option are being executed. Any help is greatly appreciated.

// Karma configuration file, see link for more information
// https://karma-runner.github.io/1.0/config/configuration-file.html

module.exports = function (config) {
  config.set({
    basePath: '',
    exclude: [
      'src/app/app.component-two.spec.ts'
    ],
    frameworks: ['jasmine', '@angular/cli'],
    plugins: [
      require('karma-jasmine'),
      require('karma-chrome-launcher'),
      require('karma-jasmine-html-reporter'),
      require('karma-coverage-istanbul-reporter'),
      require('@angular/cli/plugins/karma')
    ],
    client:{
      clearContext: false // leave Jasmine Spec Runner output visible in browser
    },
    coverageIstanbulReporter: {
      reports: [ 'html', 'lcovonly' ],
      fixWebpackSourcePaths: true
    },
    angularCli: {
      environment: 'dev'
    },
    reporters: ['progress', 'kjhtml'],
    port: 9876,
    colors: true,
    logLevel: config.LOG_INFO,
    autoWatch: true,
    browsers: ['Chrome'],
    singleRun: false
  });
};

Answer 1

You can exclude the file in the tsconfig.spec.json:

{
  "extends": "../tsconfig.json",
  "compilerOptions": { ... },
  "files": [
    "test.ts"
  ],
  "include": [
    "**/*.spec.ts",
    "**/*.d.ts"
  ],
  "exclude": [
    "app/app.component-two.spec.ts"    <------------------
  ]

Answer 2

Use src/test.ts

import { getTestBed } from '@angular/core/testing';
import { BrowserDynamicTestingModule, platformBrowserDynamicTesting } from '@angular/platform-browser-dynamic/testing';
import 'zone.js/dist/zone-testing';

declare const require: {
  context(
    path: string,
    deep?: boolean,
    filter?: RegExp
  ): {
    keys(): string[];
    <T>(id: string): T;
  };
};

const excludedSpecs = ['./app/app.component-two.spec.ts'];

// First, initialize the Angular testing environment.
getTestBed().initTestEnvironment(BrowserDynamicTestingModule, platformBrowserDynamicTesting());
// Then we find all the tests.
const context = require.context('./', true, /\.spec\.ts$/);

// And load the modules.
context
  .keys()
  .filter(file => excludedSpecs.includes(file) === false)
  .forEach(context);