test_mcp_tool_issue_948.py

import os
from unittest.mock import patch

from tools.mcp_tool import _format_connect_error, _resolve_stdio_command


def test_resolve_stdio_command_falls_back_to_hermes_node_bin(tmp_path):
    node_bin = tmp_path / "node" / "bin"
    node_bin.mkdir(parents=True)
    npx_path = node_bin / "npx"
    npx_path.write_text("#!/bin/sh\nexit 0\n", encoding="utf-8")
    npx_path.chmod(0o755)

    with patch.dict("os.environ", {"HERMES_HOME": str(tmp_path)}, clear=False):
        command, env = _resolve_stdio_command("npx", {"PATH": "/usr/bin"})

    assert command == str(npx_path)
    assert env["PATH"].split(os.pathsep)[0] == str(node_bin)


def test_resolve_stdio_command_respects_explicit_empty_path():
    seen_paths = []

    def _fake_which(_cmd, path=None):
        seen_paths.append(path)
        if path is None:
            return "/usr/bin/python"
        return None

    with patch("tools.mcp_tool.shutil.which", side_effect=_fake_which):
        command, env = _resolve_stdio_command("python", {"PATH": ""})

    assert command == "python"
    assert env["PATH"] == ""
    assert seen_paths == [""]


def test_format_connect_error_unwraps_exception_group():
    error = ExceptionGroup(
        "unhandled errors in a TaskGroup",
        [FileNotFoundError(2, "No such file or directory", "node")],
    )

    message = _format_connect_error(error)

    assert "missing executable 'node'" in message