Debugging ​

VSCode ​

Quick way to debug tests in VSCode is via JavaScript Debug Terminal. Open a new JavaScript Debug Terminal and run npm run test or vitest directly. this works with any code ran in Node, so will work with most JS testing frameworks

You can also add a dedicated launch configuration to debug a test file in VSCode:

{
  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
  "version": "0.2.0",
  "configurations": [
    {
      "type": "node",
      "request": "launch",
      "name": "Debug Current Test File",
      "autoAttachChildProcesses": true,
      "skipFiles": ["<node_internals>/**", "**/node_modules/**"],
      "program": "${workspaceRoot}/node_modules/vitest/vitest.mjs",
      "args": ["run", "${relativeFile}"],
      "smartStep": true,
      "console": "integratedTerminal"
    }
  ]
}

{
  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
  "version": "0.2.0",
  "configurations": [
    {
      "type": "node",
      "request": "launch",
      "name": "Debug Current Test File",
      "autoAttachChildProcesses": true,
      "skipFiles": ["<node_internals>/**", "**/node_modules/**"],
      "program": "${workspaceRoot}/node_modules/vitest/vitest.mjs",
      "args": ["run", "${relativeFile}"],
      "smartStep": true,
      "console": "integratedTerminal"
    }
  ]
}

Then in the debug tab, ensure 'Debug Current Test File' is selected. You can then open the test file you want to debug and press F5 to start debugging.

IntelliJ IDEA ​

Create a 'Node.js' run configuration. Use the following settings to run all tests in debug mode:

Then run this configuration in debug mode. The IDE will stop at JS/TS breakpoints set in the editor.

Node Inspector, e.g. Chrome DevTools ​

Vitest also supports debugging tests without IDEs. However this requires that tests are not run parallel. Use one of the following commands to launch Vitest.

# To run in a single worker
vitest --inspect-brk --single-thread

# To run in a child process
vitest --inspect-brk  --single-thread --no-threads

# To run in a single worker
vitest --inspect-brk --single-thread

# To run in a child process
vitest --inspect-brk  --single-thread --no-threads

Once Vitest starts it will stop execution and waits for you to open developer tools that can connect to NodeJS inspector. You can use Chrome DevTools for this by opening chrome://inspect on browser.

In watch mode you can keep the debugger open during test re-runs by using the --single-thread --isolate false options.