metamask-extension/docs/tests/jest.md

Getting Started

Running a Jest test

> yarn jest <path>

Debugging

Debugging Jest in VS Code

1. Open VS Code

2. Open the “Run and Debug” panel (⇧⌘D)

3. Click the “JavaScript Debug Terminal” button to open the Terminal

4. Run Jest using Node

   > yarn jest --watch <path>
   

Additional methods and information to debug in VS Code can be found here

Debugging Jest on Chrome DevTools

1. Run Jest using Node with the V8 Inspector

   > node --inspect ./node_modules/.bin/jest --watch -i <path>
   
   or
   
   > node --inspect ./node_modules/.bin/jest <path>
   

   Options:

   node:
   
   			--inspect=[host:]port
                Activate inspector on host:port.  Default is 127.0.0.1:9229.
   
                V8 Inspector integration allows attaching Chrome DevTools and IDEs
   						 to Node.js instances for debugging and profiling.  It uses the
   						 Chrome DevTools Protocol.
   
   jest:
   
   			--watch                       Watch files for changes and rerun tests
                                       related to changed files. If you want to
                                       re-run all tests when a file has changed,
                                       use the `--watchAll` option.       [boolean]
   
   	-i, --runInBand                   Run all tests serially in the current
                                       process (rather than creating a worker pool
                                       of child processes that run tests). This is
                                       sometimes useful for debugging, but such use
                                       cases are pretty rare.             [boolean]
   

2. Open Chrome DevTools for Node

   1. Open a Chromium browser
   2. Go to chrome://inspect/#devices
   3. Click “Open dedicated DevTools for Node” link