Files
temp/features/mocks/mock_mcp_transport.py
freemo b96138b88e fix(mcp): extract error message from content[0].text per MCP 1.4.0 protocol
MCPToolAdapter.invoke() was reading error messages from result.get('error',
'unknown error'), but the MCP 1.4.0 protocol returns errors in the content
field as a list of content items with type and text keys. This caused every
error from a real MCP 1.4.0-compliant server to be silently replaced with
the string 'unknown error'.

Changes:
- src/cleveragents/mcp/adapter.py: extract error_text from content[0].text
  with safe guards (isinstance check, length check) and fallback to
  'unknown error' when content is absent or empty
- features/mocks/mock_mcp_transport.py: return MCP 1.4.0-compliant error
  responses using content list format instead of the non-standard error key
- features/tdd_mcp_error_content_key.feature: Behave scenario verifying
  correct error extraction from MCP 1.4.0 content arrays (written as TDD
  issue-capture, @tdd_expected_fail removed after fix applied)
- features/steps/tdd_mcp_error_content_key_steps.py: step definitions for
  the new scenario including _MCP14ErrorTransport mock subclass

All 51 MCP adapter scenarios pass. Typecheck: 0 errors. Lint: clean.

ISSUES CLOSED: #2158
2026-04-03 19:03:15 +00:00

71 lines
2.2 KiB
Python

"""Shared mock MCP transport for Behave and Robot Framework tests."""
from __future__ import annotations
from typing import Any
from cleveragents.mcp.adapter import MCPServerConfig, MCPTransport
class MockMCPTransport(MCPTransport):
"""In-memory mock transport simulating an MCP server.
Supports configurable tools, connection failures, invocation results,
invocation errors, and tool-level timeouts for deterministic testing.
"""
def __init__(
self,
tools: list[dict[str, Any]] | None = None,
*,
fail_connect: bool = False,
invoke_results: dict[str, dict[str, Any]] | None = None,
invoke_errors: dict[str, str] | None = None,
timeout_tools: set[str] | None = None,
) -> None:
self._tools = tools or []
self._fail_connect = fail_connect
self._invoke_results = invoke_results or {}
self._invoke_errors = invoke_errors or {}
self._timeout_tools = timeout_tools or set()
self._connected = False
def connect(self, config: MCPServerConfig) -> dict[str, Any]:
if self._fail_connect:
msg = "Mock connection refused"
raise ConnectionRefusedError(msg)
self._connected = True
return {"capabilities": {"tools": True}}
def call(self, method: str, params: dict[str, Any]) -> dict[str, Any]:
if method == "tools/list":
return {"tools": list(self._tools)}
if method == "tools/call":
tool_name = params.get("name", "")
if tool_name in self._timeout_tools:
msg = f"Tool '{tool_name}' exceeded timeout"
raise TimeoutError(msg)
if tool_name in self._invoke_errors:
return {
"isError": True,
"content": [
{"type": "text", "text": self._invoke_errors[tool_name]}
],
}
if tool_name in self._invoke_results:
return {"content": self._invoke_results[tool_name]}
return {"content": {"result": "ok"}}
return {}
def close(self) -> None:
self._connected = False
def add_tool(self, tool: dict[str, Any]) -> None:
self._tools.append(tool)