How to step into external functions/packages in Visual Studio Code when debugging Python?

This is done by customising your debugger.

If you haven't already, you need to initialise the debugger customisation. You can do this by opening the debugger section in the side bar and selecting create a launch.json file.

Once this is done, a launch.json file will be created in a .vscode folder in your workspace.

Edit this file. It will look something like this:

{
    ...,
    "configurations": [
        {
            "name": "Python: Current File",
            "type": "python",
            "request": "launch",
            "program": "${file}",
            "console": "integratedTerminal"
        }
    ]
}

Add "justMyCode": false to the "Python: Current File" configuration, like this:

{
    ...,
    "configurations": [
        {
            "name": "Python: Current File",
            "type": "python",
            "request": "launch",
            "program": "${file}",
            "console": "integratedTerminal",
            "justMyCode": false
        }
    ]
}

True as of Visual Studio Code version 1.59.0.

Reference: https://code.visualstudio.com/docs/python/debugging

The configurations in launch.json file as follows work for me.

    "configurations": [
    {
        "name": "Python: Current File",
        "type": "python",
        "request": "test",
        "program": "${file}",
        "console": "integratedTerminal",
        "justMyCode": false,
        "purpose": ["debug-in-terminal"]
    }
]

A debugger configuration with

"debugOptions": ["DebugStdLib"]

added in launch.json in fact will step into user-defined and pip-installed modules, contrary to what's written in the main question.

For those using the standard VSCode Debugger, a little more clarification on how to configure this in VS Code might be needed

Create Your Debugger Configuration As Follows

Open up your .vscode/launch.json

Add a configuration {} to the configurations list:

"configurations": []

This one will be recognized by the built-in VSCode Debugger:

{
  "name": "Python: Debug Tests",
  "type": "python",
  "request": "launch",
  "program": "${file}",
  "purpose": ["debug-test"],
  "console": "integratedTerminal",
  "justMyCode": false
}

Key points:

1. purpose should be set to ["debug-test"]
2. "justMyCode": should be set to false.

References: Official VSCode Docs

If you are debuging a Jupyter Notebook, you may want to add to your .vscode/settings.json. See here.

  "jupyter.debugJustMyCode": false 

If you use coverage, you need to deactivate coverage during test debug. Add the following to your launch.json

"env": { "PYTEST_ADDOPTS": "--no-cov" }

Full configuration

// .vscode/settings.json
{
  "jupyter.debugJustMyCode": false
}

// .vscode/launch.json
{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Python: Debug Tests",
      "type": "debugpy",
      "request": "launch",
      "program": "${file}",
      "purpose": ["debug-test"],
      "console": "integratedTerminal",
      "justMyCode": false,
      "env": { "PYTEST_ADDOPTS": "--no-cov" }
    }
  ]
}

Most of the time, I debug unit tests rather than the running application.

If that is also the case on your side and you use:

• Visual Studio Code
• pytest
• The Python Test Explorer for Visual Studio Code (A test runner extension (adds a debug menu and provided debug buttons above tests directly in the IDE)) https://marketplace.visualstudio.com/items?itemName=LittleFoxTeam.vscode-python-test-adapter

Then use the following launch.json as mentionned in the plugin page:

    {
        "version": "0.2.0",
        "configurations": [
            {
                "name": "Debug test",
                "type": "python",
                "request": "attach",
                "console": "externalTerminal",
                "justMyCode": false,
                "stopOnEntry": true,
                "envFile": "${workspaceFolder}/.env.test",
                "purpose": ["debug-test"]
            }
        ]
    }