[angular] How to execute only one test spec with angular-cli

I solved this problem for myself using grunt. I have the grunt script below. What the script does is takes the command line parameter of the specific test to run and creates a copy of test.ts and puts this specific test name in there.

To run this, first install grunt-cli using:

npm install -g grunt-cli

Put the below grunt dependencies in your package.json:

"grunt": "^1.0.1",
"grunt-contrib-clean": "^1.0.0",
"grunt-contrib-copy": "^1.0.0",
"grunt-exec": "^2.0.0",
"grunt-string-replace": "^1.3.1"

To run it save the below grunt file as Gruntfile.js in your root folder. Then from command line run it as:

grunt --target=app.component

This will run app.component.spec.ts.

Grunt file is as below:

/*
This gruntfile is used to run a specific test in watch mode. Example: To run app.component.spec.ts , the Command is: 
grunt --target=app.component
Do not specific .spec.ts. If no target is specified it will run all tests.
*/
module.exports = function(grunt) {
var target = grunt.option('target') || '';
  // Project configuration.
  grunt.initConfig({
    pkg: grunt.file.readJSON('package.json'),
    clean: ['temp.conf.js','src/temp-test.ts'],
    copy: {
      main: {
        files: [
             {expand: false, cwd: '.', src: ['karma.conf.js'], dest: 'temp.conf.js'},
             {expand: false, cwd: '.', src: ['src/test.ts'], dest: 'src/temp-test.ts'}
             ],
      }
    },
    'string-replace': {
          dist: {
            files: {
              'temp.conf.js': 'temp.conf.js',
              'src/temp-test.ts': 'src/temp-test.ts'
            },
            options: {
              replacements: [{
                pattern: /test.ts/ig,
                replacement: 'temp-test.ts'
              },
              {
                pattern: /const context =.*/ig,
                replacement: 'const context = require.context(\'./\', true, /'+target+'\\\.spec\\\.ts$/);'
              }]
            }
        }
    },
    'exec': {
        sleep: {
          //The sleep command is needed here, else webpack compile fails since it seems like the files in the previous step were touched too recently
          command: 'ping 127.0.0.1 -n 4 > nul',
          stdout: true,
          stderr: true
        },
        ng_test: {
          command: 'ng test --config=temp.conf.js',
          stdout: true,
          stderr: true
        }
    }
  });

  // Load the plugin that provides the "uglify" task.
    grunt.loadNpmTasks('grunt-contrib-clean');
    grunt.loadNpmTasks('grunt-contrib-copy');
    grunt.loadNpmTasks('grunt-string-replace');
    grunt.loadNpmTasks('grunt-exec');
  // Default task(s).
  grunt.registerTask('default', ['clean','copy','string-replace','exec']);

};