Fix test isolation issues for GitHub Actions compatibility

Key fixes implemented:
- Added preserve_modules pytest fixture to save/restore module state between tests
- Fixed test_widget_without_ipython to properly clean up module cache
- Resolved all test failures caused by module state corruption

Technical solutions:
1. Module state preservation fixture prevents tests from corrupting each other
2. Proper cleanup in test_widget_without_ipython restores original module
3. All GitHub Actions compatibility tests now use preserve_modules fixture

Results:
- All 293 tests now pass consistently (was failing 7-17 tests)
- Tests pass both individually and when run in full suite
- GitHub Actions simulation works correctly without errors

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: jeremymanning

tests/test_github_actions_compat.py

@@ -11,10 +11,35 @@
 import pytest
 
 
+@pytest.fixture
+def preserve_modules():
+    """Preserve module state before and after test."""
+    # Save original modules
+    original_modules = {}
+    modules_to_preserve = [
+        mod for mod in sys.modules.keys() if mod.startswith("clustrix")
+    ]
+    for mod in modules_to_preserve:
+        original_modules[mod] = sys.modules.get(mod)
+
+    yield
+
+    # Clear any test modules
+    modules_to_clear = [mod for mod in sys.modules.keys() if mod.startswith("clustrix")]
+    for mod in modules_to_clear:
+        if mod in sys.modules:
+            del sys.modules[mod]
+
+    # Restore original modules
+    for mod, value in original_modules.items():
+        if value is not None:
+            sys.modules[mod] = value
+
+
 class TestGitHubActionsCompatibility:
     """Test compatibility with GitHub Actions CI/CD environment."""
 
-    def test_notebook_magic_without_dependencies(self):
+    def test_notebook_magic_without_dependencies(self, preserve_modules):
         """Test notebook magic works when IPython/ipywidgets are completely unavailable."""
         # Clear any existing clustrix modules
         modules_to_clear = [
@@ -56,7 +81,7 @@ def test_notebook_magic_without_dependencies(self):
                 # Should return None (graceful failure)
                 assert result is None
 
-    def test_widget_creation_without_dependencies(self):
+    def test_widget_creation_without_dependencies(self, preserve_modules):
         """Test widget creation fails gracefully when dependencies missing."""
         # Clear any existing clustrix modules
         modules_to_clear = [
@@ -80,7 +105,7 @@ def test_widget_creation_without_dependencies(self):
             ):
                 EnhancedClusterConfigWidget()
 
-    def test_auto_display_without_dependencies(self):
+    def test_auto_display_without_dependencies(self, preserve_modules):
         """Test auto display function handles missing dependencies gracefully."""
         # Clear any existing clustrix modules
         modules_to_clear = [
@@ -101,7 +126,7 @@ def test_auto_display_without_dependencies(self):
             # Should not raise any exceptions
             auto_display_on_import()
 
-    def test_load_ipython_extension_without_dependencies(self):
+    def test_load_ipython_extension_without_dependencies(self, preserve_modules):
         """Test IPython extension loading handles missing dependencies."""
         # Clear any existing clustrix modules
         modules_to_clear = [
@@ -132,7 +157,7 @@ def test_load_ipython_extension_without_dependencies(self):
                 # Should not try to register magic function
                 assert not mock_ipython.register_magic_function.called
 
-    def test_module_import_chain_without_dependencies(self):
+    def test_module_import_chain_without_dependencies(self, preserve_modules):
         """Test the full module import chain works without dependencies."""
         # Clear any existing clustrix modules
         modules_to_clear = [

tests/test_notebook_magic.py

@@ -186,11 +186,25 @@ def test_widget_auto_display_flag(self, mock_ipython_environment):
 
     def test_widget_without_ipython(self):
         """Test widget creation fails without IPython."""
-        with patch("clustrix.notebook_magic.IPYTHON_AVAILABLE", False):
-            with pytest.raises(
-                ImportError, match="IPython and ipywidgets are required"
-            ):
-                EnhancedClusterConfigWidget()
+        # Clear the module cache to ensure clean import
+        import sys
+
+        original_module = sys.modules.get("clustrix.notebook_magic")
+        try:
+            if "clustrix.notebook_magic" in sys.modules:
+                del sys.modules["clustrix.notebook_magic"]
+
+            with patch.dict("sys.modules", {"IPython": None, "ipywidgets": None}):
+                from clustrix.notebook_magic import EnhancedClusterConfigWidget
+
+                with pytest.raises(
+                    ImportError, match="IPython and ipywidgets are required"
+                ):
+                    EnhancedClusterConfigWidget()
+        finally:
+            # Restore the original module
+            if original_module:
+                sys.modules["clustrix.notebook_magic"] = original_module
 
     def test_config_file_loading(self, mock_ipython_environment):
         """Test configuration loading from files."""