Note: This post applies to Angular. The 2+ version of Angular.
Are you trying to run your Angular 2 unit test and the Karma test runner is not finding any tests to execute? This is exactly what happened to me when I tried to run the unit tests that are included as part of the project that the Angular CLI
The test runner should have found 3 tests to execute but as your could see above it didn’t find any test to execute. Never having used Karma before, I was unsure what the issue was or where to start troubleshooting. However, when the Karma
test runner executes it started up Chrome and the UI had a Debug button on it so I figured that would be a good first step.
I was slightly disappointed when I clicked on the Debug button as it just opened up a new tab blank tab. After a bit of reading, it turns out that you are supposed to open the Chrome Developer Tools on that new blank tab that the Debug button
opened. Once I opened the Chrome Developer Tools, I noticed that the console had the following error.
Chrome should have run the test.ts file with no problems and it is obviously not a video file. After a bit of searching, I ran across Angular CLI Issue 2125 that had a potential
workaround of adding a mime type to the Karma configuration. Below is the configuration that you need to add to the karma.conf.js file.
Once you update the configuration you need to stop Karma and re-run it with the npm run test command. It should now find and execute 3 tests.
Now you are ready to go test your Angular application. If you are looking for a good testing reference, check out the Angular Testing Guide.