Running a Single Jest Test

Jest runs tests in parallel by default, file by file.

That means if you add a .only on an it or describe, that only applies in the context of a single file. So if you have a test suite with 5 different test files and execute tests with jest, 4 test files will run all their tests and one file will run it's only test.

If you want only a single test to run, you need to add that .only and narrow jest's scope to that single test file: jest src/path/to/test.js.