Hermes-agent

tests/tools/test_mcp_capability_gating.py

@@ -0,0 +1,158 @@
+"""Tests for capability-gated MCP tool discovery and keepalive.
+
+Prompt-only / resource-only MCP servers do not implement the ``tools/*``
+request family. Per the MCP spec, ``InitializeResult.capabilities.tools``
+is non-None iff the server supports it. Before this fix, Hermes always
+called ``tools/list`` during discovery and as the keepalive probe — both
+raised ``McpError(-32601 Method not found)`` against such servers, so a
+prompt-only server could never stay connected.
+
+Ported from anomalyco/opencode#31271.
+"""
+import asyncio
+from types import SimpleNamespace
+from unittest.mock import AsyncMock
+
+import pytest
+
+from tools.mcp_tool import MCPServerTask
+
+
+def _caps(tools=None, prompts=None, resources=None):
+    """Build a fake InitializeResult with the given capability sub-objects."""
+    return SimpleNamespace(
+        capabilities=SimpleNamespace(tools=tools, prompts=prompts, resources=resources)
+    )
+
+
+class TestAdvertisesTools:
+    def test_true_when_tools_capability_present(self):
+        task = MCPServerTask("test")
+        task.initialize_result = _caps(tools=SimpleNamespace(listChanged=True))
+        assert task._advertises_tools() is True
+
+    def test_false_for_prompt_only_server(self):
+        task = MCPServerTask("test")
+        task.initialize_result = _caps(prompts=SimpleNamespace(listChanged=None))
+        assert task._advertises_tools() is False
+
+    def test_false_for_resource_only_server(self):
+        task = MCPServerTask("test")
+        task.initialize_result = _caps(resources=SimpleNamespace())
+        assert task._advertises_tools() is False
+
+    def test_legacy_fallback_no_initialize_result(self):
+        """No captured capabilities → preserve old always-list_tools behavior."""
+        task = MCPServerTask("test")
+        assert task.initialize_result is None
+        assert task._advertises_tools() is True
+
+    def test_legacy_fallback_no_capabilities_attr(self):
+        task = MCPServerTask("test")
+        task.initialize_result = SimpleNamespace()  # no .capabilities
+        assert task._advertises_tools() is True
+
+
+@pytest.mark.asyncio
+class TestDiscoverToolsGating:
+    async def test_skips_list_tools_for_prompt_only_server(self):
+        task = MCPServerTask("test")
+        task.initialize_result = _caps(prompts=SimpleNamespace())
+        task.session = SimpleNamespace(list_tools=AsyncMock())
+        task._tools = ["stale"]
+
+        await task._discover_tools()
+
+        task.session.list_tools.assert_not_called()
+        assert task._tools == []
+
+    async def test_calls_list_tools_for_tool_capable_server(self):
+        task = MCPServerTask("test")
+        task.initialize_result = _caps(tools=SimpleNamespace())
+        fake_tool = SimpleNamespace(name="echo")
+        task.session = SimpleNamespace(
+            list_tools=AsyncMock(return_value=SimpleNamespace(tools=[fake_tool]))
+        )
+
+        await task._discover_tools()
+
+        task.session.list_tools.assert_awaited_once()
+        assert task._tools == [fake_tool]
+
+    async def test_legacy_fallback_still_calls_list_tools(self):
+        task = MCPServerTask("test")
+        task.session = SimpleNamespace(
+            list_tools=AsyncMock(return_value=SimpleNamespace(tools=[]))
+        )
+
+        await task._discover_tools()
+
+        task.session.list_tools.assert_awaited_once()
+
+
+@pytest.mark.asyncio
+class TestRefreshToolsGating:
+    async def test_refresh_noop_for_prompt_only_server(self):
+        task = MCPServerTask("test")
+        task.initialize_result = _caps(prompts=SimpleNamespace())
+        task.session = SimpleNamespace(list_tools=AsyncMock())
+
+        await task._refresh_tools()
+
+        task.session.list_tools.assert_not_called()
+
+
+@pytest.mark.asyncio
+class TestKeepaliveProbe:
+    async def _run_one_keepalive_cycle(self, task):
+        """Drive _wait_for_lifecycle_event through exactly one keepalive
+        timeout, then fire shutdown so it returns."""
+        real_wait = asyncio.wait
+        cycles = {"n": 0}
+
+        async def fake_wait(tasks, timeout=None, return_when=None):
+            cycles["n"] += 1
+            if cycles["n"] == 1:
+                # Simulate keepalive timeout: nothing completed.
+                return set(), set(tasks)
+            # Second cycle: let shutdown win.
+            task._shutdown_event.set()
+            return await real_wait(
+                tasks, timeout=0.5, return_when=return_when or asyncio.FIRST_COMPLETED
+            )
+
+        import tools.mcp_tool as mcp_mod
+        orig = mcp_mod.asyncio.wait
+        mcp_mod.asyncio.wait = fake_wait
+        try:
+            return await task._wait_for_lifecycle_event()
+        finally:
+            mcp_mod.asyncio.wait = orig
+
+    async def test_keepalive_uses_ping_for_prompt_only_server(self):
+        task = MCPServerTask("test")
+        task.initialize_result = _caps(prompts=SimpleNamespace())
+        task.session = SimpleNamespace(
+            list_tools=AsyncMock(),
+            send_ping=AsyncMock(),
+        )
+
+        reason = await self._run_one_keepalive_cycle(task)
+
+        assert reason == "shutdown"
+        task.session.send_ping.assert_awaited_once()
+        task.session.list_tools.assert_not_called()
+
+    async def test_keepalive_uses_list_tools_for_tool_capable_server(self):
+        task = MCPServerTask("test")
+        task.initialize_result = _caps(tools=SimpleNamespace())
+        task.session = SimpleNamespace(
+            list_tools=AsyncMock(return_value=SimpleNamespace(tools=[])),
+            send_ping=AsyncMock(),
+        )
+
+        reason = await self._run_one_keepalive_cycle(task)
+
+        assert reason == "shutdown"
+        task.session.list_tools.assert_awaited_once()
+        task.session.send_ping.assert_not_called()