How to run a single test file in Jasmine/Karma Angular?

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As a developer, there is no limit to learning. We always need to be up to date with technologies as well as the upcoming or current features which are trending in the market.

Recently, I was looking for the best way to optimize my angular code.I have gone through a lot of articles and as we know it is limitless. Then I thought of consolidating the checklist for writing cleaner code for Angular which helped me and might help others too.

These small articles not only help you to write a better TypeScript or JavaScript Code but also clear the concepts of front-end technologies. This will help you to build your strong base and can help you in the upcoming frontend interviews.

One of the most basic topics in any programming is writing unit test cases and run the test cases. As Angular uses Karma/Jasmine tools which run for all applications but what if we want to run specific test cases? Yes, Angular does have provision for this too. Let’s see how we can run a single test case file in Angular?

  1. You can go to src/test.ts and can change the following line:

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


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

2. Jasmine also supports prefix describe and it methods with an f (for focus): fdescribe and fit. If we can use either of these, Karma will only run the relevant tests. To focus on the current file, you can just take the top level describe and change it to fdescribe.

This example code runs just the first test:

Here is the Jasmine documentation on Focusing Specs, and here is related articles.


Are you preparing for interviews? Here are frequently asked interview questions in Angular. It covers the Latest interview questions for Angular and Frontend development. Let’s check how many of these questions you can answer?

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