test(billing-cost-management-mcp-server): restore tool modules reloaded with an identity decorator (#4873)

The cost-allocation-tags, cost-category, storage-lens and unified-sql
tests reload their tool module with FastMCP.tool patched to an identity
decorator and never reload it back, so the module's server is left with
no registered tools for every later test file. Each file now has a
module-scoped fixture that reloads the real module after its tests, as
the billing-conductor and cost-optimization-hub tests do.

Author: finklen-amazon

src/billing-cost-management-mcp-server/tests/tools/test_cost_allocation_tags_tools.py

@@ -34,6 +34,21 @@
 from unittest.mock import AsyncMock, MagicMock, patch
 
 
+@pytest.fixture(scope='module', autouse=True)
+def _restore_real_tool_module():
+    """Reload the module with the real FastMCP.tool after this file's tests.
+
+    _reload_with_identity_decorator() leaves the module's server with no registered tools;
+    restoring it keeps later test files from seeing that state.
+    """
+    yield
+    from awslabs.billing_cost_management_mcp_server.tools import (
+        cost_allocation_tags_tools as module,
+    )
+
+    importlib.reload(module)
+
+
 def _reload_with_identity_decorator() -> Any:
     """Reload module with FastMCP.tool patched to return the original function."""
     from awslabs.billing_cost_management_mcp_server.tools import (

src/billing-cost-management-mcp-server/tests/tools/test_cost_category_tools.py

@@ -39,6 +39,19 @@
 COST_CATEGORY_ARN = 'arn:aws:ce::123456789012:costcategory/abcd-1234-efgh-5678'
 
 
+@pytest.fixture(scope='module', autouse=True)
+def _restore_real_tool_module():
+    """Reload the module with the real FastMCP.tool after this file's tests.
+
+    _reload_with_identity_decorator() leaves the module's server with no registered tools;
+    restoring it keeps later test files from seeing that state.
+    """
+    yield
+    from awslabs.billing_cost_management_mcp_server.tools import cost_category_tools as module
+
+    importlib.reload(module)
+
+
 def _reload_with_identity_decorator() -> Any:
     """Reload module with FastMCP.tool patched to return the original function."""
     from awslabs.billing_cost_management_mcp_server.tools import cost_category_tools as mod

src/billing-cost-management-mcp-server/tests/tools/test_storage_lens_tools.py

@@ -354,6 +354,19 @@ def test_server_initialization():
     )
 
 
+@pytest.fixture(scope='module', autouse=True)
+def _restore_real_tool_module():
+    """Reload the module with the real FastMCP.tool after this file's tests.
+
+    _reload_storage_lens_with_identity_decorator() leaves the module's server with no registered tools;
+    restoring it keeps later test files from seeing that state.
+    """
+    yield
+    from awslabs.billing_cost_management_mcp_server.tools import storage_lens_tools as module
+
+    importlib.reload(module)
+
+
 def _reload_storage_lens_with_identity_decorator():
     """Reload storage_lens_tools with FastMCP.tool patched to return the original function unchanged (identity decorator).
 

src/billing-cost-management-mcp-server/tests/tools/test_unified_sql_tools.py

@@ -81,6 +81,19 @@ def test_unified_sql_server_initialization():
     assert unified_sql_server.name == 'unified-sql-tools'
 
 
+@pytest.fixture(scope='module', autouse=True)
+def _restore_real_tool_module():
+    """Reload the module with the real FastMCP.tool after this file's tests.
+
+    _reload_unified_sql_with_identity_decorator() leaves the module's server with no registered tools;
+    restoring it keeps later test files from seeing that state.
+    """
+    yield
+    from awslabs.billing_cost_management_mcp_server.tools import unified_sql_tools as module
+
+    importlib.reload(module)
+
+
 def _reload_unified_sql_with_identity_decorator():
     """Reload unified_sql_tools with FastMCP.tool patched to return the original function unchanged (identity decorator).