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If you’re contributing to API Extractor, you’ll eventually want to run it in a debugger. If you open VS Code in the apps/api-extractor folder, it contains a launch.json file with premade debugger configurations for running API Extractor on various test projects in the build-tests folder.

For example, to analyze build-tests/api-extractor-test-01 in the debugger, you would do this:

  1. Make sure that project has been compiled (since API extractor processes .d.ts files, not .ts files):

    $ cd ./build-tests/api-extractor-test-01
    $ rushx build

    (npm run build would also work)

  2. Open VS Code in the apps/api-extractor folder.

  3. Click on the “Debug” icon on the left toolbar (Ctrl+Shift+D).

  4. Choose the "test-01" configuration from the combo box.

  5. Click the green “play” button (F5).

The api-extractor-scenarios project is slightly tricky because it has many different entry points. For each entry point, the runScenarios.ts driver will create a complete api-extractor.json style config file in the temp/configs folder. Thus, you need to manually edit the debugger configuration to specify the one you want. The section looks like this:


    . . .
      "type": "node",
      "request": "launch",
      "name": "scenario",
      "program": "${workspaceFolder}/lib/start.js",
      "cwd": "${workspaceFolder}/../../build-tests/api-extractor-scenarios",
      "args": [
      "sourceMaps": true
    . . .

Change the --config parameter from "./temp/configs/api-extractor-typeof.json" to instead specify the particular config file for the scenario you want to debug.

By the way, if you want to add a new scenario to api-extractor-scenarios, don’t forget to register it in config/build-config.json.