Fix tox configuration

[aromanielloNTIA]

Switching the build system to hatchling broke the configuration for tox.

This update fixes the tox configuration, moves it to pyproject.toml, and updates the related part of the README.

A future version of tox will natively support configuration in pyproject.toml, rather than the legacy version currently implemented in this PR. (See tox-dev/tox#999)

[ofek]

Would adding isolated_build = true under [tox] work instead?

[aromanielloNTIA]

@ofek I went back and forth about the best way to do this. When I use the tox config:

[tox]
envlist = py{38,39,310}
skip_missing_interpreters = True
isolated_build = True

[testenv]
deps =
    pytest >= 7.1.2
    pytest-cov >= 3.0.0
commands = pytest

...

I get: WARNING: could not copy distfile to H:\.tox\distshare at the beginning of the testing output when running tox.

The upside to the implementation in this PR is that this warning doesn't show up (I can't find much information about what its implications are), and the testing dependencies are only defined once in pyproject.toml. The downside is that additional [dev] dependencies are installed in the testing environments unnecessarily.

A better solution may be to create a new set of optional dependencies (listed under [project.optional-dependencies] in pyproject.toml) just for the testing environment. This would still require multiply-defined testing requirements. I would expect that when tox adds native support for pyproject.toml configuration, this will become a bit less awkward.

[ofek]

Have you tried Hatch environments?

[aromanielloNTIA]

@ofek We have internally discussed using Hatch for this repository after this issue was raised. We plan to test out Hatch and see if it is the solution we want to use longer-term, but for now we just want a quick fix for tox.

[ofek]

When the time comes, this:

[tox]
envlist = py{38,39,310}
skip_missing_interpreters = True
skipsdist = True

[testenv]
commands =
    pip install .[dev]
    pytest

[testenv:coverage]
commands =
    pip install .[dev]
    pytest --cov --cov-append --cov-report=term-missing --no-cov-on-fail

could become in a hatch.toml:

[[envs.default.matrix]]
python = ["38", "39", "310"]

[envs.default.scripts]
test = "pytest"
test-cov = "pytest --cov --cov-append --cov-report=term-missing --no-cov-on-fail"

[aromanielloNTIA]

Thanks for the feedback and assistance, @ofek!

[jhazentia]

Looks good, thanks!