Proper tests

Author: Kludex

CLAUDE.md

@@ -17,7 +17,7 @@ This document contains critical information about working with this codebase. Fo
    - Functions must be focused and small
    - Follow existing patterns exactly
    - Line length: 120 chars maximum
-   - FORBIDDEN: imports inside functions
+   - FORBIDDEN: imports inside functions. THEY SHOULD BE AT THE TOP OF THE FILE.
 
 3. Testing Requirements
    - Framework: `uv run --frozen pytest`

src/mcp/client/_memory.py

@@ -86,6 +86,6 @@ async def __aexit__(
         self, exc_type: type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
     ) -> None:
         """Close the transport and stop the server."""
-        if self._cm is not None:
+        if self._cm is not None:  # pragma: no branch
             await self._cm.__aexit__(exc_type, exc_val, exc_tb)
             self._cm = None

src/mcp/client/streamable_http.py

@@ -489,9 +489,10 @@ async def terminate_session(self, client: httpx.AsyncClient) -> None:
         except Exception as exc:  # pragma: no cover
             logger.warning(f"Session termination failed: {exc}")
 
+    # TODO(Marcelo): Check the TODO below, and cover this with tests if necessary.
     def get_session_id(self) -> str | None:
         """Get the current session ID."""
-        return self.session_id
+        return self.session_id  # pragma: no cover
 
 
 # TODO(Marcelo): I've dropped the `get_session_id` callback because it breaks the Transport protocol. Is that needed?

tests/client/test_client.py

@@ -2,11 +2,14 @@
 
 from __future__ import annotations
 
+from unittest.mock import patch
+
 import anyio
 import pytest
 from inline_snapshot import snapshot
 
 import mcp.types as types
+from mcp.client._memory import InMemoryTransport
 from mcp.client.client import Client
 from mcp.server import Server
 from mcp.server.mcpserver import MCPServer
@@ -285,3 +288,21 @@ async def test_complete_with_prompt_reference(simple_server: Server):
         ref = types.PromptReference(type="ref/prompt", name="test_prompt")
         result = await client.complete(ref=ref, argument={"name": "arg", "value": "test"})
         assert result == snapshot(types.CompleteResult(completion=types.Completion(values=[])))
+
+
+def test_client_with_url_initializes_streamable_http_transport():
+    with patch("mcp.client.client.streamable_http_client") as mock:
+        _ = Client("http://localhost:8000/mcp")
+    mock.assert_called_once_with("http://localhost:8000/mcp")
+
+
+async def test_client_uses_transport_directly(app: MCPServer):
+    transport = InMemoryTransport(app)
+    async with Client(transport) as client:
+        result = await client.call_tool("greet", {"name": "Transport"})
+        assert result == snapshot(
+            CallToolResult(
+                content=[TextContent(text="Hello, Transport!")],
+                structured_content={"result": "Hello, Transport!"},
+            )
+        )