Since at least 2019:

npm test -- bar.spec.js

In 2015:

In order to run a specific test, you'll need to use the jest command. npm test will not work. To access jest directly on the command line, install it via npm i -g jest-cli or yarn global add jest-cli.

Then simply run your specific test with jest bar.spec.js.

Note: You don't have to enter the full path to your test file. The argument is interpreted as a regular expression. Any part of the full path that uniquely identifies a file suffices.

I discovered that Jasmine allows you to prefix describe and it methods with an f (for focus): fdescribe and fit. If you use either of these, Karma will only run the relevant tests. To focus the current file, you can just take the top level describe and change it to fdescribe. If you use Jasmine prior to version 2.1, the focusing keywords are: iit and ddescribe.

This example code runs just the first test:

// Jasmine versions >/=2.1 use 'fdescribe'; versions <2.1 use 'ddescribe'
fdescribe('MySpec1', function () {
    it('should do something', function () {
        // ...
    });
});

describe('MyOtherSpec', function () {
    it('should do something else', function () {
        // ...
    });
});

Here is the Jasmine documentation on Focusing Specs, and here is a related SO article that provides additional thoughtful solutions.

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