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 can use Chrome DevTools to debug Jest tests.

First, start Node debugger in your project:

node --inspect-brk  --runInBand 

Examples:

• If you install Jest locally (Linux example):

  node --inspect-brk ./node_modules/jest/bin/jest.js --runInBand mymodule/test.js

• If you install Jest globally (Windows example):

  node --inspect-brk "C:\\Program Files\\nodejs\\node_modules\\jest\\bin\\jest.js" --runInBand mymodule\\test.js

Then, you can open the Google Chrome browser, and type in the address bar:

chrome://inspect

Now click the inspect link under "Remote Target" to open Chrome DevTools.

Note that you probably need to add the source code folder to the workspace in chrome-devtools, so as to be able to set breakpoints.

Now you can press F8 to start debugging.

[FYI]:

• My Node version: v10.11.0
• My Jest version: 23.6.0
• My Google Chrome version: 71.0.3578.98

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[Update] Regarding the step of adding the source code folder to the workspace in chrome-devtools (as asked by Sam), it looks like below:

And then you can open your script files and set the breakpoints:

You find the simple demo project on my GitHub repo.