MAINT Remove setuptools dependency from tests (scikit-learn#29261)

Author: lesteve

build_tools/azure/cpython_free_threaded_lock.txt

@@ -2,7 +2,7 @@
 # This file is autogenerated by pip-compile with Python 3.13
 # by the following command:
 #
-#    pip-compile --allow-unsafe --output-file=/scikit-learn/build_tools/azure/cpython_free_threaded_lock.txt /scikit-learn/build_tools/azure/cpython_free_threaded_requirements.txt
+#    pip-compile --output-file=/scikit-learn/build_tools/azure/cpython_free_threaded_lock.txt /scikit-learn/build_tools/azure/cpython_free_threaded_requirements.txt
 #
 execnet==2.1.1
     # via pytest-xdist
@@ -33,7 +33,3 @@ pytest-xdist==3.6.1
     # via -r /scikit-learn/build_tools/azure/cpython_free_threaded_requirements.txt
 threadpoolctl==3.5.0
     # via -r /scikit-learn/build_tools/azure/cpython_free_threaded_requirements.txt
-
-# The following packages are considered to be unsafe in a requirements file:
-setuptools==70.0.0
-    # via -r /scikit-learn/build_tools/azure/cpython_free_threaded_requirements.txt

build_tools/azure/cpython_free_threaded_requirements.txt

@@ -1,5 +1,5 @@
 # To generate cpython_free_threaded_lock.txt, use the following command:
-# docker run -v $PWD:/scikit-learn -it ubuntu bash -c 'export DEBIAN_FRONTEND=noninteractive; apt-get -yq update; apt-get install software-properties-common ccache -y; add-apt-repository --yes ppa:deadsnakes/nightly; apt-get update -y; apt-get install -y --no-install-recommends python3.13-dev python3.13-venv python3.13-nogil; python3.13t -m venv /venvs/myenv; source /venvs/myenv/bin/activate; pip install pip-tools; pip-compile --allow-unsafe /scikit-learn/build_tools/azure/cpython_free_threaded_requirements.txt -o /scikit-learn/build_tools/azure/cpython_free_threaded_lock.txt'
+# docker run -v $PWD:/scikit-learn -it ubuntu bash -c 'export DEBIAN_FRONTEND=noninteractive; apt-get -yq update; apt-get install software-properties-common ccache -y; add-apt-repository --yes ppa:deadsnakes/nightly; apt-get update -y; apt-get install -y --no-install-recommends python3.13-dev python3.13-venv python3.13-nogil; python3.13t -m venv /venvs/myenv; source /venvs/myenv/bin/activate; pip install pip-tools; pip-compile /scikit-learn/build_tools/azure/cpython_free_threaded_requirements.txt -o /scikit-learn/build_tools/azure/cpython_free_threaded_lock.txt'
 
 # The reason behind it is that you need python-3.13t to generate the pip lock
 # file. For pure Python wheel this does not really matter. But when there are
@@ -12,6 +12,3 @@ pytest
 pytest-xdist
 ninja
 meson-python
-# For some reason some of our tests require setuptools.
-# TODO: update those tests to remove the dependency.
-setuptools

sklearn/_build_utils/pre_build_helpers.py

@@ -7,11 +7,11 @@
 import tempfile
 import textwrap
 
-from setuptools.command.build_ext import customize_compiler, new_compiler
-
 
 def compile_test_program(code, extra_preargs=None, extra_postargs=None):
     """Check that some C code can be compiled and run"""
+    from setuptools.command.build_ext import customize_compiler, new_compiler
+
     ccompiler = new_compiler()
     customize_compiler(ccompiler)
 

sklearn/tests/test_common.py

@@ -177,6 +177,7 @@ def test_check_estimator_generate_only():
 
 
 def test_setup_py_check():
+    pytest.importorskip("setuptools")
     # Smoke test `python setup.py check` command run at the root of the
     # scikit-learn source tree.
     cwd = os.getcwd()