Flaky test fix (#1050)

tests/issues/test_188_concurrency.py

@@ -14,29 +14,38 @@ _resource_name = "slow://slow_resource"
 @pytest.mark.anyio
 async def test_messages_are_executed_concurrently():
     server = FastMCP("test")
+    call_timestamps = []
 
     @server.tool("sleep")
     async def sleep_tool():
+        call_timestamps.append(("tool_start_time", anyio.current_time()))
         await anyio.sleep(_sleep_time_seconds)
+        call_timestamps.append(("tool_end_time", anyio.current_time()))
         return "done"
 
     @server.resource(_resource_name)
     async def slow_resource():
+        call_timestamps.append(("resource_start_time", anyio.current_time()))
         await anyio.sleep(_sleep_time_seconds)
+        call_timestamps.append(("resource_end_time", anyio.current_time()))
         return "slow"
 
     async with create_session(server._mcp_server) as client_session:
-        start_time = anyio.current_time()
         async with anyio.create_task_group() as tg:
             for _ in range(10):
                 tg.start_soon(client_session.call_tool, "sleep")
                 tg.start_soon(client_session.read_resource, AnyUrl(_resource_name))
 
-        end_time = anyio.current_time()
-
-        duration = end_time - start_time
-        assert duration < 10 * _sleep_time_seconds
-        print(duration)
+        active_calls = 0
+        max_concurrent_calls = 0
+        for call_type, _ in sorted(call_timestamps, key=lambda x: x[1]):
+            if "start" in call_type:
+                active_calls += 1
+                max_concurrent_calls = max(max_concurrent_calls, active_calls)
+            else:
+                active_calls -= 1
+        print(f"Max concurrent calls: {max_concurrent_calls}")
+        assert max_concurrent_calls > 1, "No concurrent calls were executed"
 
 
 def main():