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MagMueller
98 lines
3.5 KiB
Python
98 lines
3.5 KiB
Python
"""Regression test for MCP tool calls that fail at the application level.
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Per the MCP spec, `CallToolResult.isError` signals that the tool itself
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reported a failure (e.g. "File not found") even though the RPC call
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succeeded. `MCPClient` must surface that as a failed `ActionResult`
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instead of silently treating `result.content` as a successful result.
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"""
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from unittest.mock import AsyncMock, MagicMock
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import pytest
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from mcp import types
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from browser_use import Tools
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from browser_use.mcp.client import MCPClient
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def _make_connected_client() -> MCPClient:
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client = MCPClient(server_name='test-server', command='test-command')
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client._telemetry = MagicMock()
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client._connected = True
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client.session = MagicMock()
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return client
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@pytest.mark.asyncio
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async def test_mcp_tool_isError_true_is_surfaced_as_action_result_error():
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"""An MCP tool that reports isError=True must not look like a success."""
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client = _make_connected_client()
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client.session.call_tool = AsyncMock( # type: ignore[union-attr]
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return_value=types.CallToolResult(
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content=[types.TextContent(type='text', text='File not found: /tmp/does-not-exist.txt')],
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is_error=True,
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)
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)
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tools = Tools()
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tool = types.Tool(name='read_file', description='Read a file', input_schema={'type': 'object', 'properties': {}})
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client._register_tool_as_action(tools.registry, 'read_file', tool)
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result = await tools.registry.execute_action('read_file', {})
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assert result.success is False, f'expected success=False for a failed MCP tool call, got {result!r}'
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assert result.error, f'expected result.error to be set for a failed MCP tool call, got {result!r}'
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assert 'File not found' in result.error
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@pytest.mark.asyncio
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async def test_parameterized_mcp_tool_isError_true_is_surfaced_as_action_result_error():
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"""The parameter-model wrapper must surface application-level MCP errors too."""
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client = _make_connected_client()
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client.session.call_tool = AsyncMock( # type: ignore[union-attr]
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return_value=types.CallToolResult(
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content=[types.TextContent(type='text', text='File not found: /tmp/does-not-exist.txt')],
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is_error=True,
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)
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)
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tools = Tools()
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tool = types.Tool(
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name='read_file',
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description='Read a file',
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input_schema={
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'type': 'object',
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'properties': {'path': {'type': 'string'}},
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'required': ['path'],
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},
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)
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client._register_tool_as_action(tools.registry, 'read_file', tool)
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result = await tools.registry.execute_action('read_file', {'path': '/tmp/does-not-exist.txt'})
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assert result.success is False, f'expected success=False for a failed MCP tool call, got {result!r}'
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assert result.error, f'expected result.error to be set for a failed MCP tool call, got {result!r}'
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assert 'File not found' in result.error
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client.session.call_tool.assert_awaited_once_with('read_file', {'path': '/tmp/does-not-exist.txt'}) # type: ignore[union-attr]
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@pytest.mark.asyncio
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async def test_mcp_tool_isError_false_still_succeeds():
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"""Sanity check: a normal successful MCP tool call is unaffected by the fix."""
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client = _make_connected_client()
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client.session.call_tool = AsyncMock( # type: ignore[union-attr]
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return_value=types.CallToolResult(
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content=[types.TextContent(type='text', text='ok')],
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is_error=False,
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)
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)
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tools = Tools()
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tool = types.Tool(name='read_file', description='Read a file', input_schema={'type': 'object', 'properties': {}})
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client._register_tool_as_action(tools.registry, 'read_file', tool)
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result = await tools.registry.execute_action('read_file', {})
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assert result.error is None
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assert result.extracted_content == 'ok'
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