Debug Tests in NG Test

Update for Angular version 9

The source files have been moved but you can still debug this way if you do the following steps

• In devtools, select the sources tab
• Press CTRL + P
• Type in the name of the file you want to debug

Valid for versions below 9

The other answers are completely valid answers but having been using Angular for around 18 months now I tend to do it in the browser - chrome tools!

Run ng test then f12 and find the spec file via the webpack context. Add a breakpoint(s) and refresh and it will hit said breakpoints. As per screenshot

This is what worked for me with:

• Angular 9.0.6 + Visual Studio Code 1.43.2
• Angular 8.2.13 + Visual Studio Code 1.39.2
• Angular 7, Angular CLI 1.0.* and Chrome on Windows 7.

---

Change configuration files

In your project root directory open karma.conf.js. Right after singleRun: false add , followed by this section:

    customLaunchers: {
      ChromeDebug: {
        base: 'Chrome',
        flags: [ '--remote-debugging-port=9333' ]
      }
    }

Add configuration to .vscode/launch.json.

• For versions 8.* - 9.* (note "pathMapping section!):

  {
    "type": "chrome",
    "request": "attach",
    "name": "Unit tests",
    "address": "localhost",
    "port": 9333,
    "sourceMaps": true,
    "webRoot": "${workspaceFolder}",
    "pathMapping": {
      "/_karma_webpack_": "${workspaceFolder}"
    }
  },
  

• For version 7.*:

  {
    "type": "chrome",
    "request": "attach",
    "name": "Unit tests",
    "address": "localhost",
    "port": 9333,
    "sourceMaps": true,
    "webRoot": "${workspaceFolder}"
  },
  

---

Start debugging

1. Run ng test --browsers ChromeDebug

2. Wait for Chrome browser to start. You will see something like this in command line:

   01 06 2017 16:07:29.276:INFO [launcher]: Launching browser ChromeDebug with unlimited concurrency
   

3. Set the breakpoint in one of your .spec.ts files.

4. In Visual Studio Code choose Unit tests debug configuration and hit F5 ("Start Debugging" button).

5. Press Shift+Ctrl+F5 or refresh the Chrome window to rerun the tests and hit the breakpoint.

---

For convenience

You can also modify your package.json and add a new script:

"test-debug": "ng test --browsers ChromeDebug",

Then next time you want to start ng test with debugging just run:

npm run test-debug

---

References:

• Debugging Jasmine Unit tests running with Karma runner in VS Code
• Debugging Karma tests with VSCode
• Angular CLI 8.1.3 Debug Unit Tests configuration - Unverified breakpoint
• microsoft/vscode-recipes - Chrome Debugging with Angular CLI

In the new release of VSCode (1.14.0) they follow this recipe:

You can debug the Angular App entirely ( including the unit tests ), the recipe is straightforward.