Fix test isolation for clear_import_cache utility

tests/utils/test_import_utils.py

@@ -1,23 +1,114 @@
+import importlib
+import os
+import subprocess
 import sys
 
-from transformers.utils.import_utils import clear_import_cache
+import pytest
 
+import transformers.utils.logging
+from transformers.utils.import_utils import _LazyModule
+
+
+@pytest.fixture(scope="function", autouse=True)
+def isolate_module_cache():
+    """Fixture to save and restore the module cache state before and after each test."""
+    # Save initial state
+    initial_modules = dict(sys.modules)
+
+    # Save logging state
+    initial_verbosity = transformers.utils.logging.get_verbosity()
+    initial_env_vars = {}
+    for env_var in ["TRANSFORMERS_VERBOSITY"]:
+        if env_var in os.environ:
+            initial_env_vars[env_var] = os.environ[env_var]
+
+    yield
+
+    # Restore initial state after test
+    current_modules = set(sys.modules.keys())
+    added_modules = current_modules - set(initial_modules.keys())
+
+    # Remove any modules that were added during the test
+    for name in added_modules:
+        if name in sys.modules:
+            del sys.modules[name]
+
+    # Restore original modules
+    for name, module in initial_modules.items():
+        sys.modules[name] = module
+        if isinstance(module, _LazyModule):
+            # Re-initialize lazy module cache
+            importlib.reload(module)
+
+    # Restore logging state
+    transformers.utils.logging.set_verbosity(initial_verbosity)
+    transformers.utils.logging._reset_library_root_logger()
+
+    # Restore environment variables
+    for env_var in ["TRANSFORMERS_VERBOSITY"]:
+        if env_var in initial_env_vars:
+            os.environ[env_var] = initial_env_vars[env_var]
+        elif env_var in os.environ:
+            del os.environ[env_var]
 
-def test_clear_import_cache():
-    # Import some transformers modules
 
-    # Get initial module count
-    initial_modules = {name: mod for name, mod in sys.modules.items() if name.startswith("transformers.")}
+def run_in_subprocess(func_name):
+    """Run a test function in a separate subprocess to fully isolate it."""
+    test_script = f"""
+import os
+import sys
+import importlib
+from transformers.utils.import_utils import clear_import_cache
+
+def {func_name}():
+    # Import the function to test
+    from transformers.utils.import_utils import clear_import_cache
 
-    # Verify we have some modules loaded
-    assert len(initial_modules) > 0
+    # First, ensure we have some transformers modules loaded
+    import transformers.models.auto.modeling_auto
 
-    # Clear cache
+    # Save initial state
+    initial_modules = {{name: mod for name, mod in sys.modules.items() if name.startswith("transformers.")}}
+    assert len(initial_modules) > 0, "No transformers modules loaded before test"
+
+    # Run the test
     clear_import_cache()
 
-    # Check modules were removed
-    remaining_modules = {name: mod for name, mod in sys.modules.items() if name.startswith("transformers.")}
-    assert len(remaining_modules) < len(initial_modules)
+    # Verify modules were removed
+    remaining_modules = {{name: mod for name, mod in sys.modules.items() if name.startswith("transformers.")}}
+    assert len(remaining_modules) < len(initial_modules), "No modules were removed"
+
+    # Import and verify module exists
+    from transformers.models.auto import modeling_auto
+    assert "transformers.models.auto.modeling_auto" in sys.modules
+    assert modeling_auto.__name__ == "transformers.models.auto.modeling_auto"
+
+    return True
 
-    # Verify we can reimport
-    assert "transformers" in sys.modules
+# Run the test function directly
+result = {func_name}()
+sys.exit(0 if result else 1)
+"""
+    # Create a temporary script file
+    import tempfile
+
+    with tempfile.NamedTemporaryFile(suffix=".py", delete=False) as f:
+        f.write(test_script.encode("utf-8"))
+        temp_script = f.name
+
+    try:
+        # Run the script in a subprocess
+        result = subprocess.run([sys.executable, temp_script], capture_output=True, text=True)
+        # Check if the test passed
+        passed = result.returncode == 0
+        if not passed:
+            print(f"Subprocess test failed with output:\n{result.stdout}\n{result.stderr}")
+        return passed
+    finally:
+        # Clean up the temporary file
+        os.unlink(temp_script)
+
+
+def test_clear_import_cache():
+    """Wrapper that runs the actual test in a subprocess."""
+    assert run_in_subprocess("test_clear_import_cache_impl")