How to have test-only dependencies

[rdong8]

I've tried this:

[tool.hatch.envs.test]
dependencies = ["pytest", "aiohttp"]

[[tool.hatch.envs.hatch-test.matrix]]
python = ["3.13"]
envs = ["test"]

But when I run hatch test I still get ModuleNotFoundError: No module named 'aiohttp'. How can I make it so that hatch test installs the test dependencies first?

[pwestlak-xilinx]

I think you might want tool.hatch.envs.hatch-test to get the built-in environment used for hatch test.

[SirHegel]

hatch test never looks at [tool.hatch.envs.test]. It runs in the internal hatch-test environment and its matrix variants (hatch-test.py3.13, ...), and envs = ["test"] inside the matrix does not connect the two; it only adds a matrix variable literally named envs. So aiohttp was installed in an environment the tests do not use.

Add test-only dependencies to hatch-test with extra-dependencies, which keeps the built-in test stack:

[tool.hatch.envs.hatch-test]
extra-dependencies = ["aiohttp"]

[[tool.hatch.envs.hatch-test.matrix]]
python = ["3.13"]

Then hatch test (or hatch test -py 3.13). pytest does not need to be listed: the environment's default dependencies already include pytest, pytest-mock, pytest-randomly, pytest-rerunfailures, pytest-xdist, coverage[toml] and coverage-enable-subprocess. Setting dependencies instead of extra-dependencies would replace that list.

If you also want a plain hatch run environment with the same packages, that is a separate definition ([tool.hatch.envs.default] or a dedicated environment); the internal environments use themselves as template and do not derive from default.

References:

• https://hatch.pypa.io/latest/config/internal/testing/#dependencies
• Defaults: https://github.com/pypa/hatch/blob/929362c909899556ae4efd1f61a3b078677ad235/src/hatch/env/internal/test.py