Use logfire[testing] for OTel test assertions

Author: Kludex

pyproject.toml

@@ -72,6 +72,7 @@ dev = [
     "coverage[toml]>=7.10.7,<=7.13",
     "pillow>=12.0",
     "strict-no-cover",
+    "logfire[testing]",
 ]
 docs = [
     "mkdocs>=1.6.1",

tests/shared/test_otel.py

@@ -1,12 +1,39 @@
 from __future__ import annotations
 
 import pytest
+from logfire.testing import CaptureLogfire
 
-from mcp.shared._otel import otel_span
+from mcp.client.client import Client
+from mcp.server.mcpserver import MCPServer
 
 pytestmark = pytest.mark.anyio
 
 
-def test_otel_span_creates_span():
-    with otel_span("test.span", kind="CLIENT", attributes={"key": "value"}) as span:
-        assert span is not None
+async def test_client_and_server_spans(capfire: CaptureLogfire):
+    """Verify that calling a tool produces client and server spans with correct attributes."""
+    server = MCPServer("test")
+
+    @server.tool()
+    def greet(name: str) -> str:
+        """Greet someone."""
+        return f"Hello, {name}!"
+
+    async with Client(server) as client:
+        result = await client.call_tool("greet", {"name": "World"})
+
+    assert result.content[0].text == "Hello, World!"  # type: ignore[union-attr]
+
+    spans = capfire.exporter.exported_spans_as_dict()
+    span_names = {s["name"] for s in spans}
+
+    assert "MCP tools/call greet" in span_names
+    assert "MCP handle tools/call greet" in span_names
+
+    client_span = next(s for s in spans if s["name"] == "MCP tools/call greet")
+    server_span = next(s for s in spans if s["name"] == "MCP handle tools/call greet")
+
+    assert client_span["attributes"]["mcp.method.name"] == "tools/call"
+    assert server_span["attributes"]["mcp.method.name"] == "tools/call"
+
+    # Server span should be in the same trace as the client span (context propagation).
+    assert server_span["context"]["trace_id"] == client_span["context"]["trace_id"]