Could you say a bit more as to why please? Is there a way to modify this behaviour?

Here’s an example that works, although the by line test is a bit less convenient since your cursor must be on the precise line of the test you want to run:

{
  "version": "0.2.0",
  "configurations": [
    {
      "type": "mix_task",
      "name": "mix test",
      "request": "launch",
      "task": "test",
      "taskArgs": [],
      "startApps": true,
      "projectDir": "${workspaceRoot}",
      "requireFiles": ["test/**/test_helper.exs", "test/**/*_test.exs"]
    },
    {
      "type": "mix_task",
      "name": "mix test current file",
      "request": "launch",
      "task": "test",
      "taskArgs": [
        "${relativeFile}"
      ],
      "startApps": true,
      "projectDir": "${workspaceRoot}",
      "requireFiles": [
        "test/**/test_helper.exs",
        "${relativeFile}"
      ]
    },
    {
      "type": "mix_task",
      "name": "mix test current line number",
      "request": "launch",
      "task": "test",
      "taskArgs": [
        "${relativeFile}:${lineNumber}"
      ],
      "startApps": true,
      "projectDir": "${workspaceRoot}",
      "requireFiles": [
        "test/**/test_helper.exs",
        "${relativeFile}"
      ]
    }
  ]
}

Any thoughts on how we might be able to speed this up? Some performance degradation is fine (and I imagine unavoidable) but it’s incredibly slow to use at the moment, and often quicker to add a few IO.inspect statements. Perhaps there is a way of specifying only certain modules that we’re interested in instrumenting?

With VSCode ElixirLS extension it’s now possible to debug test directly from Testing tab or via right clicking the icon next to test definition and selecting Debug test. It will run the debugger with a launch configuration for mix test task and fall back to a default one if not found

I’m not sure you understood my question. It has nothing to do with Jest or JavaScript. These are Elixir tests that use ExUnit. The steps you mention don’t explain anything either.