Add skip_import to PythonPackage and use it in py-nilearn (#32664)

* Add skip_import to PythonPackage and use it in py-nilearn

* Fix dependencies

lib/spack/docs/build_systems/pythonpackage.rst

@@ -582,6 +582,19 @@ libraries. Make sure not to add modules/packages containing the word
 "test", as these likely won't end up in the installation directory,
 or may require test dependencies like pytest to be installed.
 
+Instead of defining the ``import_modules`` explicity, only the subset
+of module names to be skipped can be defined by using ``skip_modules``.
+If a defined module has submodules, they are skipped as well, e.g.,
+in case the ``plotting`` modules should be excluded from the
+automatically detected ``import_modules`` ``['nilearn', 'nilearn.surface',
+'nilearn.plotting', 'nilearn.plotting.data']`` set:
+
+.. code-block:: python
+
+        skip_modules = ['nilearn.plotting']
+
+This will set ``import_modules`` to ``['nilearn', 'nilearn.surface']``
+
 Import tests can be run during the installation using ``spack install
 --test=root`` or at any time after the installation using
 ``spack test run``.

lib/spack/spack/build_systems/python.py

@@ -138,12 +138,28 @@ def import_modules(self):
                     path.replace(root + os.sep, "", 1).replace(".py", "").replace("/", ".")
                 )
 
-        modules = [mod for mod in modules if re.match("[a-zA-Z0-9._]+$", mod)]
+        modules = [
+            mod
+            for mod in modules
+            if re.match("[a-zA-Z0-9._]+$", mod) and not any(map(mod.startswith, self.skip_modules))
+        ]
 
         tty.debug("Detected the following modules: {0}".format(modules))
 
         return modules
 
+    @property
+    def skip_modules(self):
+        """Names of modules that should be skipped when running tests.
+
+        These are a subset of import_modules. If a module has submodules,
+        they are skipped as well (meaning a.b is skipped if a is contained).
+
+        Returns:
+            list: list of strings of module names
+        """
+        return []
+
     @property
     def build_directory(self):
         """The root directory of the Python package.