Add some tests (#24)

These tests are loosely based on the ones in colcon-core and validate
the functionality of this package.

test/spell_check.words

@@ -1,9 +1,11 @@
 apache
+autouse
 colcon
 darwin
 dyld
 dylib
 iterdir
+libfoo
 linter
 linux
 namedtuple
@@ -15,4 +17,8 @@ pydocstyle
 pytest
 scspell
 setuptools
+skipif
 thomas
+tmpdir
+todo
+unittest

test/test_environment_library_path.py

@@ -0,0 +1,63 @@
+# Copyright 2025 Open Source Robotics Foundation, Inc.
+# Licensed under the Apache License, Version 2.0
+
+from pathlib import Path
+import platform
+import sys
+from unittest.mock import patch
+
+from colcon_library_path.environment.library_path import LibraryPathEnvironment
+import pytest
+
+skip_unless_windows = pytest.mark.skipif(
+    sys.platform != 'win32',
+    reason='Test is only applicable to Windows systems')
+
+skip_unless_darwin = pytest.mark.skipif(
+   platform.system() != 'Darwin',
+   reason='Test is only applicable to Darwin systems')
+
+skip_if_darwin_or_windows = pytest.mark.skipif(
+    sys.platform == 'win32' or platform.system() == 'Darwin',
+    reason='Test is not applicable to Darwin or Windows systems')
+
+
+@pytest.fixture(scope='module', autouse=True)
+def env_hook_patch():
+    with patch(
+        'colcon_core.shell.create_environment_hook',
+        return_value=['/some/hook', '/other/hook']
+    ):
+        yield
+
+
+@pytest.mark.parametrize('search_path', [
+    pytest.param('lib/libfoo.so', marks=skip_if_darwin_or_windows),
+    pytest.param('lib64/libfoo.so', marks=skip_if_darwin_or_windows),
+    pytest.param('lib/libfoo.dylib', marks=skip_unless_darwin),
+    pytest.param('bin/foo.dll', marks=skip_unless_windows),
+])
+def test_library_path(tmpdir, search_path):
+    extension = LibraryPathEnvironment()
+    prefix_path = Path(tmpdir)
+    library = prefix_path / search_path
+
+    # no libraries or directories
+    hooks = extension.create_environment_hooks(prefix_path, 'pkg_name')
+    assert len(hooks) == 0
+
+    # library directory exists but is empty
+    library.parent.mkdir(parents=True)
+    hooks = extension.create_environment_hooks(prefix_path, 'pkg_name')
+    assert len(hooks) == 0
+
+    # subdirectories named similarly to library
+    # TODO: This should probably be fixed
+    # library.with_name('dir_' + library.name).mkdir(parents=True)
+    # hooks = extension.create_environment_hooks(prefix_path, 'pkg_name')
+    # assert len(hooks) == 0
+
+    # library exists
+    library.touch()
+    hooks = extension.create_environment_hooks(prefix_path, 'pkg_name')
+    assert len(hooks) > 0