How to execute only one test spec with angular-cli

Each of your .spec.ts file have all its tests grouped in describe block like this:

describe('SomeComponent', () => {...}

You can easily run just this single block, by prefixing the describe function name with f:

fdescribe('SomeComponent', () => {...}

If you have such function, no other describe blocks will run. Btw. you can do similar thing with it => fit and there is also a "blacklist" version - x. So:

fdescribe and fit causes only functions marked this way to run

xdescribe and xit causes all but functions marked this way to run

Configure test.ts file inside src folder:

const context = require.context('./', true, /\.spec\.ts$/);

Replace /\.spec\.ts$/ with the file name you want to test. For example: /app.component\.spec\.ts$/

This will run test only for app.component.spec.ts.

You can test only specific file with the Angular CLI (the ng command) like this:

ng test --main ./path/to/test.ts

Further docs are at https://angular.io/cli/test

Note that while this works for standalone library files, it will not work for angular components/services/etc. This is because angular files have dependencies on other files (namely src/test.ts in Angular 7). Sadly the --main flag doesn't take multiple arguments.

This worked for me in every case:

ng test --include='**/dealer.service.spec.ts'

However, I usually got "TypeError: Cannot read property 'ngModule' of null" for this:

ng test --main src/app/services/dealer.service.spec.ts

Version of @angular/cli 10.0.4

use --include

it's work with --include

ng test --include src/app/path-to-component/path-component.component.spec.ts

I tried --main but it shows all fail results while it's not. I think --main will change the main test.ts file.

If you want to be able to control which files are selected from the command line, I managed to do this for Angular 7.

In summary, you need to install @angular-devkit/build-angular:browser and then create a custom webpack plugin to pass the test file regex through. For example:

angular.json - change the test builder from @angular-devkit/build-angular:browser and set a custom config file:

...

        "test": {
          "builder": "@angular-builders/custom-webpack:browser",
          "options": {
            "customWebpackConfig": {
              "path": "./extra-webpack.config.js"
            },
...

extra-webpack.config.js - create a webpack configuration that reads the regex from the command line:

const webpack = require('webpack');
const FILTER = process.env.KARMA_FILTER;
let KARMA_SPEC_FILTER = '/.spec.ts$/';
if (FILTER) {
  KARMA_SPEC_FILTER = `/${FILTER}.spec.ts$/`;
}
module.exports = {
  plugins: [new webpack.DefinePlugin({KARMA_SPEC_FILTER})]
}

test.ts - edit the spec

...
// Then we find all the tests.
declare const KARMA_CONTEXT_SPEC: any;
const context = require.context('./', true, KARMA_CONTEXT_SPEC);

Then use as follows to override the default:

KARMA_FILTER='somefile-.*\.spec\.ts$' npm run test

I documented the backstory here, apologies in advance for types and mis-links. Credit to the answer above by @Aish-Anu for pointing me in the right direction.

In a bash terminal I like to use the double dash. Using VS Code, you can right click on the spec file in the explorer, or on the open tab. Then select 'Copy Relative Path'. Run the command below pasting the relative path in from the clipboard.

npm t -- --include relative/path/to/file.spec.ts

The double dash signals the end of your command options for npm t and passes anything after that to the next command which is pointing to ng t. It's doesn't require any modification and quickly gives desired results.

A simple way to do this is to start the describe and all it with f.

fdescribe('testecomponente', () => {
  fit('should create', () => {
    //your code 
  }
  
}
  

This is working for me in Angular 7. It is based on the --main option of the ng command. I am not sure if this option is undocumented and possibly subject to change, but it works for me. I put a line in my package.json file in scripts section. There using the --main option of with the ng test command, I specify the path to the .spec.ts file I want to execute. For example

"test 1": "ng test --main E:/WebRxAngularClient/src/app/test/shared/my-date-utils.spec.ts",

You can run the script as you run any such script. I run it in Webstorm by clicking on "test 1" in the npm section.

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']);

};

Adding to this for people like me who were searching for a way to run a single spec in Angular and found this SO.

According to the latest Angular docs (v9.0.6 at time of writing), the ng test command has an --include option where you can specify a directory of *.spec.(ts|tsx) files or just a single .spec.(ts|tsx) file itself.

https://angular.io/cli/test

Just small change need in test.ts file inside src folder:

const context = require.context('./', true, /test-example\.spec\.ts$/);

Here, test-example is the exact file name which we need to run

In the same way, if you need to test the service file only you can replace the filename like "/test-example.service"

If you are working in a project that uses monorepo architecture then you must write the project's name after script in the command line. For example:

ng test MyProject1Name -- --include='myComponent.component.spec.ts'

From angular-cli you can run this command and the test will include only that spec file which you want to.

ng test --includes path of spec file