TST: Add test for submodule detection outside of repo.

Author: DWesl

tests/test_submodule.py

@@ -0,0 +1,27 @@
+"""Test submodule detection code."""
+
+import os.path
+
+from check_python_h_first.get_submodule_paths import get_submodule_paths
+
+ROOT_DIR = os.path.dirname(os.path.dirname(__file__))
+
+
+def test_submodule_paths_gh_pages():
+    """Test that we can pick up the gh-pages submodule."""
+    results = get_submodule_paths()
+    assert set(results) == {os.path.join(ROOT_DIR, "docs", "_build", "html")}
+
+
+def test_submodule_paths_no_repo():
+    """Test that we pick up no submodules outside a repo.
+
+    Will fail if this repository is itself a submodule.
+    """
+    try:
+        _orig_dir = os.getcwd()
+        os.chdir(os.path.dirname(ROOT_DIR))
+        results = get_submodule_paths()
+        assert results == []
+    finally:
+        os.chdir(_orig_dir)