Add test capturing current behavior and missed expectation. Ref #203.

importlib_resources/tests/_compat.py

@@ -6,7 +6,20 @@
 except ImportError:
     # Python 3.9 and earlier
     class import_helper:  # type: ignore
-        from test.support import modules_setup, modules_cleanup
+        from test.support import (
+            modules_setup,
+            modules_cleanup,
+            DirsOnSysPath,
+            CleanImport,
+        )
+
+
+try:
+    from test.support import os_helper  # type: ignore
+except ImportError:
+    # Python 3.9 compat
+    class os_helper:  # type:ignore
+        from test.support import temp_dir
 
 
 try:

importlib_resources/tests/_path.py

@@ -0,0 +1,50 @@
+import pathlib
+import functools
+
+
+####
+# from jaraco.path 3.4
+
+
+def build(spec, prefix=pathlib.Path()):
+    """
+    Build a set of files/directories, as described by the spec.
+
+    Each key represents a pathname, and the value represents
+    the content. Content may be a nested directory.
+
+    >>> spec = {
+    ...     'README.txt': "A README file",
+    ...     "foo": {
+    ...         "__init__.py": "",
+    ...         "bar": {
+    ...             "__init__.py": "",
+    ...         },
+    ...         "baz.py": "# Some code",
+    ...     }
+    ... }
+    >>> tmpdir = getfixture('tmpdir')
+    >>> build(spec, tmpdir)
+    """
+    for name, contents in spec.items():
+        create(contents, pathlib.Path(prefix) / name)
+
+
+@functools.singledispatch
+def create(content, path):
+    path.mkdir(exist_ok=True)
+    build(content, prefix=path)  # type: ignore
+
+
+@create.register
+def _(content: bytes, path):
+    path.write_bytes(content)
+
+
+@create.register
+def _(content: str, path):
+    path.write_text(content)
+
+
+# end from jaraco.path
+####

importlib_resources/tests/test_files.py

@@ -1,10 +1,13 @@
 import typing
 import unittest
+import contextlib
 
 import importlib_resources as resources
 from importlib_resources.abc import Traversable
 from . import data01
 from . import util
+from . import _path
+from ._compat import os_helper, import_helper
 
 
 class FilesTests:
@@ -42,5 +45,30 @@ def setUp(self):
         self.data = namespacedata01
 
 
+class ModulesFilesTests(unittest.TestCase):
+    def setUp(self):
+        self.fixtures = contextlib.ExitStack()
+        self.addCleanup(self.fixtures.close)
+        self.site_dir = self.fixtures.enter_context(os_helper.temp_dir())
+        self.fixtures.enter_context(import_helper.DirsOnSysPath(self.site_dir))
+        self.fixtures.enter_context(import_helper.CleanImport())
+
+    def test_module_resources(self):
+        """
+        A module can have resources found adjacent to the module.
+        """
+        spec = {
+            'mod.py': '',
+            'res.txt': 'resources are the best',
+        }
+        _path.build(spec, self.site_dir)
+        import mod
+
+        # currently a failure occurs; ref #203
+        with self.assertRaisesRegex(TypeError, '.*mod.* is not a package'):
+            actual = resources.files(mod).joinpath('res.txt').read_text()
+            assert actual == spec['res.txt']
+
+
 if __name__ == '__main__':
     unittest.main()