How do you debug Jest Tests?

Question

I can't find any information on debugging my unit tests written with Jest.

How do you debug Jest Tests ?

Answer 1

You do not need Chrome for Jest tests.

The simplest solution I found is to use VS Code JavaScript Debug Terminal.

And it works with Typescript and Nrvl.Nx work-spaces out of the box.

1. Open the command palette and start Debug: JavaScript Debug Terminal:

2. Run tests in that terminal in a Watch mode npm test --watch.
3. Set a break-point in your file.
4. Make any change in a file you want to debug and save.
5. watch will run Jest tests against modified files.

When you want to narrow down the number of files run by the --watch, press p in the terminal and enter a pattern, which is just a part of the file name you want to test and hit [Enter]

To limit it to a single test in a file - focus it with f, so change it(...) to fit(...)