Testing

Testing Angular – A Guide to Robust Angular Applications.molily

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guide/testing

Your_first_suite

Jasmin Tutorial

Details

The Angular CLI downloads and install everything you need to test Angular with Jasmine testing framework.

When you run ng test, the application is built in watch mode, and lauches the Karma test runner.

You may generate a karma.conf.js running ng generate config karma, to customize karma.

Continuous Integration

You may run in CI (Continuous Integration) with:

ng test --no-watch --no-progress --browsers=ChromeHeadless

Code Coverage

To generate a coverage report:

ng test --no-watch --code-coverage

Code Coverage Enforcement

Suppose you want the code base to have a minimum of 80% code coverage.

To do so, open karma.conf.js, and add the check property in the coverageReport: key

coverageReporter: {
    dir: require('path').join(__dirname, './coverage/<project-name>'),
    subdir: '.',
    reporters: [
        { type: 'html' },
        { type: 'text-summary' }
    ],
    check: {
        global: {
            statements: 80,
            branches: 80,
            functions: 80,
            lines: 80
        }
    }
}

Executed Specific Tests

To execetute only specified choosen tests you may append a f in front of describe or it.

// Only this will run
fdescribe(() => { ... });

describe(() => {
    // Will be skipped
    it(() => { ... });
    
    // Only this will run
    fit(() => { ... });
});

Skiping Specific Tests

The same way you can specify choosen tests to skip with a x in front of describe or it.

// Will be skipped
xdescribe(() => { ... });

describe(() => {
    // Will be skipped
    xit(() => { ... });
    
    // Will run
    it(() => { ... });
});

Best Practices

DOM querying

When writing tests for your Components, you will likely have to query for specific DOM elements.

It is good practice to add to these specific tested elements a HTML property, working like ids, so they can easily be reached inside the tests.

Ex.:

<p data-test-id="user-title"> ... </p>

Angular TestBed

It creates a dynamically constructed Angular test module that emulates an Angular @NgModule.

Check the most important static methods here.

TestBed.configureTestingModule()

The TestBed.configureTestingModule() method takes a metada object that can have most of the properties of an @NgModule.

WSL Problems/Tips

If you are running tests inside WSL2, it will have problems since it requires Chrome to execute and show the results.

Running npm run test with --browsers=ChromeHeadless will help, by avoiding opening a Chrome browser. But it will still require you to install Chrome inside the WSL Ubuntu.

I tried mapping the CHROME_BIN to the external Windows Chrome executable.

But it did not work.

Install Chrome on Ubuntu

wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
sudo apt install ./google-chrome-stable_current_amd64.deb

Check to see if google-chrome autocompletes on the terminal.

Running tests on terminal only

If you just want to run the tests on the terminal just run with:

ng test --no-watch --browsers=ChromeHeadless

See test results on Chrome

Follow here or here to install VcXsrv on Windows, so that opening Chrome from ubuntu will show graphically on Windows.