modelcontextprotocol--python-sdk/tests/server/test_validation.py

"""Tests for server validation functions."""

import pytest
from mcp_types import (
    ClientCapabilities,
    SamplingCapability,
    SamplingMessage,
    SamplingToolsCapability,
    TextContent,
    Tool,
    ToolChoice,
    ToolResultContent,
    ToolUseContent,
)

from mcp.server.validation import (
    check_sampling_tools_capability,
    validate_sampling_tools,
    validate_tool_use_result_messages,
)
from mcp.shared.exceptions import MCPError

# Tests for check_sampling_tools_capability function


def test_check_sampling_tools_capability_returns_false_when_caps_none() -> None:
    """Returns False when client_caps is None."""
    assert check_sampling_tools_capability(None) is False


def test_check_sampling_tools_capability_returns_false_when_sampling_none() -> None:
    """Returns False when client_caps.sampling is None."""
    caps = ClientCapabilities()
    assert check_sampling_tools_capability(caps) is False


def test_check_sampling_tools_capability_returns_false_when_tools_none() -> None:
    """Returns False when client_caps.sampling.tools is None."""
    caps = ClientCapabilities(sampling=SamplingCapability())
    assert check_sampling_tools_capability(caps) is False


def test_check_sampling_tools_capability_returns_true_when_tools_present() -> None:
    """Returns True when sampling.tools is present."""
    caps = ClientCapabilities(sampling=SamplingCapability(tools=SamplingToolsCapability()))
    assert check_sampling_tools_capability(caps) is True


# Tests for validate_sampling_tools function


def test_validate_sampling_tools_no_error_when_tools_none() -> None:
    """No error when tools and tool_choice are None."""
    validate_sampling_tools(None, None, None)  # Should not raise


def test_validate_sampling_tools_raises_when_tools_provided_but_no_capability() -> None:
    """Raises MCPError when tools provided but client doesn't support."""
    tool = Tool(name="test", input_schema={"type": "object"})
    with pytest.raises(MCPError) as exc_info:
        validate_sampling_tools(None, [tool], None)
    assert "sampling tools capability" in str(exc_info.value)


def test_validate_sampling_tools_raises_when_tool_choice_provided_but_no_capability() -> None:
    """Raises MCPError when tool_choice provided but client doesn't support."""
    with pytest.raises(MCPError) as exc_info:
        validate_sampling_tools(None, None, ToolChoice(mode="auto"))
    assert "sampling tools capability" in str(exc_info.value)


def test_validate_sampling_tools_no_error_when_capability_present() -> None:
    """No error when client has sampling.tools capability."""
    caps = ClientCapabilities(sampling=SamplingCapability(tools=SamplingToolsCapability()))
    tool = Tool(name="test", input_schema={"type": "object"})
    validate_sampling_tools(caps, [tool], ToolChoice(mode="auto"))  # Should not raise


# Tests for validate_tool_use_result_messages function


def test_validate_tool_use_result_messages_no_error_for_empty_messages() -> None:
    """No error when messages list is empty."""
    validate_tool_use_result_messages([])  # Should not raise


def test_validate_tool_use_result_messages_no_error_for_simple_text_messages() -> None:
    """No error for simple text messages."""
    messages = [
        SamplingMessage(role="user", content=TextContent(type="text", text="Hello")),
        SamplingMessage(role="assistant", content=TextContent(type="text", text="Hi")),
    ]
    validate_tool_use_result_messages(messages)  # Should not raise


def test_validate_tool_use_result_messages_raises_when_tool_result_mixed_with_other_content() -> None:
    """Raises when tool_result is mixed with other content types."""
    messages = [
        SamplingMessage(
            role="user",
            content=[
                ToolResultContent(type="tool_result", tool_use_id="123"),
                TextContent(type="text", text="also this"),
            ],
        ),
    ]
    with pytest.raises(ValueError, match="only tool_result content"):
        validate_tool_use_result_messages(messages)


def test_validate_tool_use_result_messages_raises_when_tool_result_without_previous_tool_use() -> None:
    """Raises when tool_result appears without preceding tool_use."""
    messages = [
        SamplingMessage(
            role="user",
            content=ToolResultContent(type="tool_result", tool_use_id="123"),
        ),
    ]
    with pytest.raises(ValueError, match="previous message containing tool_use"):
        validate_tool_use_result_messages(messages)


def test_validate_tool_use_result_messages_raises_when_previous_message_has_no_tool_use() -> None:
    """Raises when tool_result follows a message that has content but no tool_use."""
    messages = [
        SamplingMessage(role="assistant", content=TextContent(type="text", text="just text")),
        SamplingMessage(role="user", content=ToolResultContent(type="tool_result", tool_use_id="tool-1")),
    ]
    with pytest.raises(ValueError, match="do not match any tool_use in the previous message"):
        validate_tool_use_result_messages(messages)


def test_validate_tool_use_result_messages_raises_when_tool_result_ids_dont_match_tool_use() -> None:
    """Raises when tool_result IDs don't match tool_use IDs."""
    messages = [
        SamplingMessage(
            role="assistant",
            content=ToolUseContent(type="tool_use", id="tool-1", name="test", input={}),
        ),
        SamplingMessage(
            role="user",
            content=ToolResultContent(type="tool_result", tool_use_id="tool-2"),
        ),
    ]
    with pytest.raises(ValueError, match="do not match"):
        validate_tool_use_result_messages(messages)


def test_validate_tool_use_result_messages_no_error_when_tool_result_matches_tool_use() -> None:
    """No error when tool_result IDs match tool_use IDs."""
    messages = [
        SamplingMessage(
            role="assistant",
            content=ToolUseContent(type="tool_use", id="tool-1", name="test", input={}),
        ),
        SamplingMessage(
            role="user",
            content=ToolResultContent(type="tool_result", tool_use_id="tool-1"),
        ),
    ]
    validate_tool_use_result_messages(messages)  # Should not raise