Before you go into debugging test case that use ava in Node.js, you can read up on knowledge about AVA framework at the following link: Ava test

The first thing to do is you have to configure file launch.json in Visual studio code. You can reference to the article Debug in C++ with VS Code to know parameter in file lauch.json.

The nex thing is the content of file launch.json.

{  
  "version": "0.2.0",
  "configurations": [    
    {
      "type": "node",
      "request": "launch",
      "name": "Debugging test case use AVA in Node.js",
      "program": "${workspaceRoot}/node_modules/ava/profile.js",
      "args": [
        "--serial",
        "${file}"           // file test case that you want to debug.
      ]
    }
  ]
}

Thanks for your reading.