Focusing and skipping tests

When writing unit tests, you might need to temporarily choose which tests to execute. You could achieve this by commenting out the tests you don't want to run, although there's also another way built in in your testing framework.

Mocha

With Mocha, you can use it.only() and describe.only() for exclusive tests. This will run just the tests marked with only and ignore the rest.

// Both tests in this describe block will run
describe.only('when something happens', () => {
    it('should do something', () => {});
    it('should do something else', () => {});
});

// This test case won't be executed
it('should also do this', () => {});

Conversely, use it.skip() and describe.skip for inclusive tests. All tests marked with skip will not be run.

// Neither of the tests in this describe block will run
describe.skip('when something happens', () => {
    it('should do something', () => {});
    it('should do something else', () => {});
});

// This test case  isn't affected by the describe.skip and will therefore be executed
it('should also do this', () => {});

You can also combine these two together. In the example below, the only test cases being run are "should do something" and "should also do this":

describe.only('when something happens', () => {
    it('should do something', () => {});
    it.skip('should do something else', () => {});
});

// This test case  isn't affected by the describe.skip and will therefore be executed
it.only('should also do this', () => {});

Jasmine

If you are using Jasmine, you can choose to run a particular test case or suite (or set of test cases/suites) by changing it() to fit() and describe() to fdescribe(), respectively.

// Both tests in this suite will run
fdescribe('when something happens', () => {
    it('should do something', () => {});
    it('should do something else', () => {});
});

// This test case won't be executed
it('should also do this', () => {});

To skip tests on the other hand, replace it() with xit() for individual test cases and describe() with xdescribe() for test suites.

// Neither of the tests in this suite will run
xdescribe('when something happens', () => {
    it('should do something', () => {});
    it('should do something else', () => {});
});

// This test case  isn't affected by the xdescribe and will therefore be run
it('should also do this', () => {});