tests: add lowest dependency tests (#1067)

Co-authored-by: ihrpr <inna@anthropic.com>

.github/workflows/shared.yml

@@ -29,6 +29,7 @@ jobs:
   test:
     runs-on: ${{ matrix.os }}
     timeout-minutes: 10
+    continue-on-error: true
     strategy:
       matrix:
         python-version: ["3.10", "3.11", "3.12", "3.13"]
@@ -48,8 +49,14 @@ jobs:
 
       - name: Run pytest
         run: uv run --frozen --no-sync pytest
-    continue-on-error: true
 
+      # This must run last as it modifies the environment!
+      - name: Run pytest with lowest versions
+        run: |
+          uv sync --all-extras --upgrade
+          uv run --no-sync pytest
+        env:
+          UV_RESOLUTION: lowest-direct
   readme-snippets:
     runs-on: ubuntu-latest
     steps:

pyproject.toml

@@ -25,7 +25,7 @@ dependencies = [
     "anyio>=4.5",
     "httpx>=0.27",
     "httpx-sse>=0.4",
-    "pydantic>=2.7.2,<3.0.0",
+    "pydantic>=2.8.0,<3.0.0",
     "starlette>=0.27",
     "python-multipart>=0.0.9",
     "sse-starlette>=1.6.1",
@@ -36,14 +36,13 @@ dependencies = [
 
 [project.optional-dependencies]
 rich = ["rich>=13.9.4"]
-cli = ["typer>=0.12.4", "python-dotenv>=1.0.0"]
+cli = ["typer>=0.16.0", "python-dotenv>=1.0.0"]
 ws = ["websockets>=15.0.1"]
 
 [project.scripts]
 mcp = "mcp.cli:app [cli]"
 
 [tool.uv]
-resolution = "lowest-direct"
 default-groups = ["dev", "docs"]
 required-version = ">=0.7.2"
 
@@ -58,6 +57,7 @@ dev = [
     "pytest-examples>=0.0.14",
     "pytest-pretty>=1.2.0",
     "inline-snapshot>=0.23.0",
+    "dirty-equals>=0.9.0",
 ]
 docs = [
     "mkdocs>=1.6.1",
@@ -124,5 +124,5 @@ filterwarnings = [
     # This should be fixed on Uvicorn's side.
     "ignore::DeprecationWarning:websockets",
     "ignore:websockets.server.WebSocketServerProtocol is deprecated:DeprecationWarning",
-    "ignore:Returning str or bytes.*:DeprecationWarning:mcp.server.lowlevel"
+    "ignore:Returning str or bytes.*:DeprecationWarning:mcp.server.lowlevel",
 ]

tests/issues/test_188_concurrency.py

@@ -1,60 +1,46 @@
 import anyio
 import pytest
-from pydantic import AnyUrl
 
 from mcp.server.fastmcp import FastMCP
-from mcp.shared.memory import (
+from mcp.shared.memory import create_connected_server_and_client_session as create_session
-    create_connected_server_and_client_session as create_session,
-)
-
-_sleep_time_seconds = 0.01
-_resource_name = "slow://slow_resource"
 
 
 @pytest.mark.anyio
 async def test_messages_are_executed_concurrently():
     server = FastMCP("test")
-    call_timestamps = []
+    event = anyio.Event()
+    tool_started = anyio.Event()
+    call_order = []
 
     @server.tool("sleep")
     async def sleep_tool():
-        call_timestamps.append(("tool_start_time", anyio.current_time()))
+        call_order.append("waiting_for_event")
-        await anyio.sleep(_sleep_time_seconds)
+        tool_started.set()
-        call_timestamps.append(("tool_end_time", anyio.current_time()))
+        await event.wait()
+        call_order.append("tool_end")
         return "done"
 
-    @server.resource(_resource_name)
+    @server.tool("trigger")
-    async def slow_resource():
+    async def trigger():
-        call_timestamps.append(("resource_start_time", anyio.current_time()))
+        # Wait for tool to start before setting the event
-        await anyio.sleep(_sleep_time_seconds)
+        await tool_started.wait()
-        call_timestamps.append(("resource_end_time", anyio.current_time()))
+        call_order.append("trigger_started")
+        event.set()
+        call_order.append("trigger_end")
         return "slow"
 
     async with create_session(server._mcp_server) as client_session:
+        # First tool will wait on event, second will set it
         async with anyio.create_task_group() as tg:
-            for _ in range(10):
+            # Start the tool first (it will wait on event)
-                tg.start_soon(client_session.call_tool, "sleep")
+            tg.start_soon(client_session.call_tool, "sleep")
-                tg.start_soon(client_session.read_resource, AnyUrl(_resource_name))
+            # Then the trigger tool will set the event to allow the first tool to continue
+            await client_session.call_tool("trigger")
 
-        active_calls = 0
+        # Verify that both ran concurrently
-        max_concurrent_calls = 0
+        assert call_order == [
-        for call_type, _ in sorted(call_timestamps, key=lambda x: x[1]):
+            "waiting_for_event",
-            if "start" in call_type:
+            "trigger_started",
-                active_calls += 1
+            "trigger_end",
-                max_concurrent_calls = max(max_concurrent_calls, active_calls)
+            "tool_end",
-            else:
+        ], f"Expected concurrent execution, but got: {call_order}"
-                active_calls -= 1
-        print(f"Max concurrent calls: {max_concurrent_calls}")
-        assert max_concurrent_calls > 1, "No concurrent calls were executed"
-
-
-def main():
-    anyio.run(test_messages_are_executed_concurrently)
-
-
-if __name__ == "__main__":
-    import logging
-
-    logging.basicConfig(level=logging.DEBUG)
-
-    main()

tests/server/fastmcp/test_func_metadata.py

@@ -3,6 +3,7 @@ from typing import Annotated, Any, TypedDict
 
 import annotated_types
 import pytest
+from dirty_equals import IsPartialDict
 from pydantic import BaseModel, Field
 
 from mcp.server.fastmcp.utilities.func_metadata import func_metadata
@@ -202,11 +203,8 @@ def test_structured_output_dict_str_types():
         return {"a": 1, "b": "hello", "c": [1, 2, 3]}
 
     meta = func_metadata(func_dict_any)
-    assert meta.output_schema == {
+
-        "additionalProperties": True,
+    assert meta.output_schema == IsPartialDict(type="object", title="func_dict_anyDictOutput")
-        "type": "object",
-        "title": "func_dict_anyDictOutput",
-    }
 
     # Test dict[str, str]
     def func_dict_str() -> dict[str, str]: