ENH/BLD: Add install tags for tests

[czgdp1807]

Same as numpy/numpy#26274

Reference issue

What does this implement/fix?

Additional information

[tylerjereddy]

This PR doesn't have a description, should I assume what you're trying to do is build on Ralf's work in NumPy to install the tests as a separate "package" for the purposes of PyPI releases? Or something else?

[rgommers]

Thanks @czgdp1807, this looks very clean now and all seems to work as advertised.

$ python -m build -wnx -Cinstall-args=--tags=runtime,python-runtime,devel
$ mv scipy-1.14.0.dev0-cp312-cp312-linux_x86_64.whl scipy-1.14.0.dev0-cp312-cp312-linux_x86_64-no-tests.whl
$ python -m build -wnx

$ ls -l dist/*.whl
... 22140538 ... dist/scipy-1.14.0.dev0-cp312-cp312-linux_x86_64-no-tests.whl
... 25101662 ... dist/scipy-1.14.0.dev0-cp312-cp312-linux_x86_64.whl

So the produced wheels are ~12% smaller. In addition, this will help people who want to strip out the tests, for example:

• Conda-forge: fragile hacks in build scripts to remove tests: https://github.com/conda-forge/scipy-feedstock/blob/39c367144d7519ad131c7fdb073bf0d2476a374c/recipe/build-output.bat#L25-L46
• Pyodide: has generic post-processing to strip tests, but that is less reliable since it's filename-based, requiring things like: https://github.com/pyodide/pyodide/blob/0c2dea7882e1cda56da7ee31c73e286461451cd5/packages/scipy/meta.yaml#L91-L93
• AWS Lamba layer for SciPy: Scipy lambda layer for 3.9 and 3.10 keithrozario/Klayers#360

A wheel for separately installable tests can be produced with a one-line diff:

diff --git a/pyproject.toml b/pyproject.toml
index ab241ac23..3fc1eecfd 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -32,7 +32,7 @@ requires = [
 ]
 
 [project]
-name = "scipy"
+name = "scipy-tests"
 version = "1.14.0.dev0"
 # TODO: add `license-files` once PEP 639 is accepted (see meson-python#88)
 #       at that point, no longer include them in `py3.install_sources()`

$ python -m build -wnx -Cinstall-args=--tags=tests
$ ls -l dist/*.whl
...  2966947 ... dist/scipy_tests-1.14.0.dev0-cp312-cp312-linux_x86_64.whl

There is another set of test files to strip, which is test extension modules:

$ ls -l build/scipy/*/*.so | rg test
-rwxr-xr-x 1 rgommers rgommers    28664 17 mei 18:04 build/scipy/integrate/_test_multivariate.cpython-312-x86_64-linux-gnu.so
-rwxr-xr-x 1 rgommers rgommers   270968 17 mei 18:04 build/scipy/integrate/_test_odeint_banded.cpython-312-x86_64-linux-gnu.so
-rwxr-xr-x 1 rgommers rgommers   151456 17 mei 18:04 build/scipy/io/_test_fortran.cpython-312-x86_64-linux-gnu.so
-rwxr-xr-x 1 rgommers rgommers    52912 17 mei 18:04 build/scipy/_lib/_test_ccallback.cpython-312-x86_64-linux-gnu.so
-rwxr-xr-x 1 rgommers rgommers   158752 21 mei 13:45 build/scipy/_lib/_test_deprecation_call.cpython-312-x86_64-linux-gnu.so
-rwxr-xr-x 1 rgommers rgommers    92272 21 mei 13:45 build/scipy/_lib/_test_deprecation_def.cpython-312-x86_64-linux-gnu.so
-rwxr-xr-x 1 rgommers rgommers    31336 17 mei 18:04 build/scipy/ndimage/_ctest.cpython-312-x86_64-linux-gnu.so
-rwxr-xr-x 1 rgommers rgommers   386480 21 mei 13:45 build/scipy/ndimage/_cytest.cpython-312-x86_64-linux-gnu.so
-rwxr-xr-x 1 rgommers rgommers  1095216 21 mei 13:45 build/scipy/special/_test_internal.cpython-312-x86_64-linux-gnu.so

Could you change the install tags on those targets to tests as well?

[czgdp1807]

I think for scipy-tests we need to do it in a separate PR. I think we need to do create two [project] (I don't know if its allowed), one for scipy (without tests) and one for scipy-tests.

[rgommers]

I think for scipy-tests we need to do it in a separate PR. I think we need to do create two [project] (I don't know if its allowed), one for scipy (without tests) and one for scipy-tests.

Yeah don't worry about that. It's not something we have to do anything about before starting to actually produce wheels without tests included. And two [project] sections are not allowed indeed.

[czgdp1807]

All ready on this PR.

[rgommers]

Found one more sizable set of files to remove, pushed a fix. With that, we're at:

• full wheel: 25.1 MB
• test-only: 4.6 MB
• wheels without tests: 20.5 MB

Once we remove the already-deprecated scipy.misc in the future, which also contains some data files, then it's down to 18.6 MB. That is getting somewhere:)

[rgommers]

Okay, let's declare victory here - in it went! Nice work @czgdp1807.

Cc @h-vetinari for visibility: for the next release it may be nice to start using this in conda-forge to produce scipy and scipy-tests, that would clean things up a lot.

[h-vetinari]

That's great news; this took a lot of manual processing on the conda-forge that will be great to get rid of. Thanks for the heads-up and the work here!

[rgommers]

gh-20812 includes docs for this new feature