fix: Fix async context manager in MCP test stubs

- Change fake_streamablehttp_client from async def to regular def
- async with expects an object with __aenter__/__aexit__, not a coroutine
- Add __path__ to make mcp modules look like packages
- Add last_kwargs tracking for header assertions
- Add proper assertions to verify headers are passed/not passed
- This fixes TypeError: 'coroutine' object does not support async context manager protocol

Co-Authored-By: João <joao@crewai.com>

lib/crewai/tests/tools/test_mcp_tool_wrapper.py

@@ -19,6 +19,11 @@ def stub_mcp_modules(monkeypatch):
     mcp_client = types.ModuleType("mcp.client")
     mcp_streamable_http = types.ModuleType("mcp.client.streamable_http")
     
+    mcp.__path__ = []
+    mcp_client.__path__ = []
+    mcp.client = mcp_client
+    mcp_client.streamable_http = mcp_streamable_http
+    
     class MockClientSession:
         def __init__(self, *args, **kwargs):
             self.initialize = AsyncMock()
@@ -28,27 +33,36 @@ def stub_mcp_modules(monkeypatch):
         async def __aenter__(self):
             return self
         
-        async def __aexit__(self, *exc):
-            pass
+        async def __aexit__(self, exc_type, exc, tb):
+            return False
     
     mcp.ClientSession = MockClientSession
     
-    async def fake_streamablehttp_client(*args, **kwargs):
-        """Mock streamablehttp_client context manager."""
+    last_kwargs = {}
+    
+    def fake_streamablehttp_client(*args, **kwargs):
+        """Mock streamablehttp_client context manager (NOT async def)."""
+        last_kwargs.clear()
+        last_kwargs.update(kwargs)
+        
         class MockContextManager:
             async def __aenter__(self):
                 return (AsyncMock(), AsyncMock(), AsyncMock())
             
-            async def __aexit__(self, *exc):
-                pass
+            async def __aexit__(self, exc_type, exc, tb):
+                return False
         
         return MockContextManager()
     
+    fake_streamablehttp_client.last_kwargs = last_kwargs
+    
     mcp_streamable_http.streamablehttp_client = fake_streamablehttp_client
     
     monkeypatch.setitem(sys.modules, "mcp", mcp)
     monkeypatch.setitem(sys.modules, "mcp.client", mcp_client)
     monkeypatch.setitem(sys.modules, "mcp.client.streamable_http", mcp_streamable_http)
+    
+    return mcp_streamable_http
 
 
 @pytest.fixture
@@ -265,7 +279,7 @@ class TestMCPToolWrapperHeaders:
         assert wrapper.mcp_server_params["headers"] == headers
 
     @pytest.mark.asyncio
-    async def test_headers_passed_to_transport(self):
+    async def test_headers_passed_to_transport(self, stub_mcp_modules):
         """Test that headers are passed to streamablehttp_client."""
         from mcp import ClientSession
         
@@ -294,11 +308,15 @@ class TestMCPToolWrapperHeaders:
         try:
             result = await wrapper._execute_tool(test_arg="test_value")
             assert result == "Test result"
+            
+            # Verify headers were passed to streamablehttp_client
+            assert "headers" in stub_mcp_modules.streamablehttp_client.last_kwargs
+            assert stub_mcp_modules.streamablehttp_client.last_kwargs["headers"] == headers
         finally:
             ClientSession.__init__ = original_init
 
     @pytest.mark.asyncio
-    async def test_no_headers_when_not_configured(self):
+    async def test_no_headers_when_not_configured(self, stub_mcp_modules):
         """Test that headers are not passed when not configured."""
         from mcp import ClientSession
         
@@ -322,6 +340,9 @@ class TestMCPToolWrapperHeaders:
         try:
             result = await wrapper._execute_tool(test_arg="test_value")
             assert result == "Test result"
+            
+            # Verify headers were NOT passed to streamablehttp_client
+            assert "headers" not in stub_mcp_modules.streamablehttp_client.last_kwargs
         finally:
             ClientSession.__init__ = original_init