Support sandboxed environment selection for testing frameworks (pytest, uinttest)

[timonviola]

The feature request is to explicitly declare, which virtual environment should be used for tests.

I have sandboxed environments:

• project dependecies (used for editable installs, etc.)
• dev (used during development)
• test (used for tests)

During development I want to set:

"python.defaultInterpreterPath": "${workspaceFolder}/.venv/dev/bin/python"

However, in that case, tests cannot be discovered:

[error] /Users/timon/work/dagcellent/dagcellent/.venv/dev/bin/python: No module named pytest

As soon as I activate the test venv, discovery works.

Note that setting:

"python.testing.pytestPath": "${workspaceFolder}/.venv/test.py3.11/bin/pytest",

seems to have no effect.

---

My .venv looks like this:

.venv
├── my_package
├── dev
└── test.py3.11

I am using hatch, but this can easily be replicated with poetry or other:

[tool.hatch.envs.dev]
extra-dependencies = [
    "pre-commit == 3.7.*",
    "ruff == 0.4.4",
    "mypy == 1.10.*",
]

[tool.hatch.envs.dev.scripts]
install = "pre-commit install --hook-type commit-msg"

[tool.hatch.envs.test]
extra-dependencies = [
    "pytest >= 8.0.0",
    "pytest-cov",
    "pytest-mock >= 3.14.0",
]