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test: rewrite cli.claude config tests to assert JSON output directly (#2311)

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Co-authored-by: claude[bot] <209825114+claude[bot]@users.noreply.github.com>
Co-authored-by: Felix Weinberger <felixweinberger@users.noreply.github.com>
This commit is contained in:
Max Isbey 2026-03-19 15:16:34 +00:00 • committed by GitHub
commit 883d893097
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GPG key ID: B5690EEEBB952194
3 changed files with 158 additions and 83 deletions
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20
src/mcp/cli/claude.py
View file

@ -33,7 +33,7 @@ def get_claude_config_path() -> Path | None: # pragma: no cover
def get_uv_path() -> str:
"""Get the full path to the uv executable."""
uv_path = shutil.which("uv")
if not uv_path: # pragma: no cover
if not uv_path:
logger.error(
"uv executable not found in PATH, falling back to 'uv'. Please ensure uv is installed and in your PATH"
)
@ -65,7 +65,7 @@ def update_claude_config(
"""
config_dir = get_claude_config_path()
uv_path = get_uv_path()
if not config_dir: # pragma: no cover
if not config_dir:
raise RuntimeError(
"Claude Desktop config directory not found. Please ensure Claude Desktop"
" is installed and has been run at least once to initialize its config."
@ -90,7 +90,7 @@ def update_claude_config(
config["mcpServers"] = {}
# Always preserve existing env vars and merge with new ones
if server_name in config["mcpServers"] and "env" in config["mcpServers"][server_name]: # pragma: no cover
if server_name in config["mcpServers"] and "env" in config["mcpServers"][server_name]:
existing_env = config["mcpServers"][server_name]["env"]
if env_vars:
# New vars take precedence over existing ones
@ -103,22 +103,26 @@ def update_claude_config(
# Collect all packages in a set to deduplicate
packages = {MCP_PACKAGE}
if with_packages: # pragma: no cover
if with_packages:
packages.update(pkg for pkg in with_packages if pkg)
# Add all packages with --with
for pkg in sorted(packages):
args.extend(["--with", pkg])
if with_editable: # pragma: no cover
if with_editable:
args.extend(["--with-editable", str(with_editable)])
# Convert file path to absolute before adding to command
# Split off any :object suffix first
if ":" in file_spec:
# First check if we have a Windows path (e.g., C:\...)
has_windows_drive = len(file_spec) > 1 and file_spec[1] == ":"
# Split on the last colon, but only if it's not part of the Windows drive letter
if ":" in (file_spec[2:] if has_windows_drive else file_spec):
file_path, server_object = file_spec.rsplit(":", 1)
file_spec = f"{Path(file_path).resolve()}:{server_object}"
else: # pragma: no cover
else:
file_spec = str(Path(file_spec).resolve())
# Add mcp run command
@ -127,7 +131,7 @@ def update_claude_config(
server_config: dict[str, Any] = {"command": uv_path, "args": args}
# Add environment variables if specified
if env_vars: # pragma: no cover
if env_vars:
server_config["env"] = env_vars
config["mcpServers"][server_name] = server_config

146
tests/cli/test_claude.py Normal file
View file

@ -0,0 +1,146 @@
"""Tests for mcp.cli.claude — Claude Desktop config file generation."""
import json
from pathlib import Path
from typing import Any
import pytest
from mcp.cli.claude import get_uv_path, update_claude_config
@pytest.fixture
def config_dir(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> Path:
"""Temp Claude config dir with get_claude_config_path and get_uv_path mocked."""
claude_dir = tmp_path / "Claude"
claude_dir.mkdir()
monkeypatch.setattr("mcp.cli.claude.get_claude_config_path", lambda: claude_dir)
monkeypatch.setattr("mcp.cli.claude.get_uv_path", lambda: "/fake/bin/uv")
return claude_dir
def _read_server(config_dir: Path, name: str) -> dict[str, Any]:
config = json.loads((config_dir / "claude_desktop_config.json").read_text())
return config["mcpServers"][name]
def test_generates_uv_run_command(config_dir: Path):
"""Should write a uv run command that invokes mcp run on the resolved file spec."""
assert update_claude_config(file_spec="server.py:app", server_name="my_server")
resolved = Path("server.py").resolve()
assert _read_server(config_dir, "my_server") == {
"command": "/fake/bin/uv",
"args": ["run", "--frozen", "--with", "mcp[cli]", "mcp", "run", f"{resolved}:app"],
}
def test_file_spec_without_object_suffix(config_dir: Path):
"""File specs without :object should still resolve to an absolute path."""
assert update_claude_config(file_spec="server.py", server_name="s")
assert _read_server(config_dir, "s")["args"][-1] == str(Path("server.py").resolve())
def test_with_packages_sorted_and_deduplicated(config_dir: Path):
"""Extra packages should appear as --with flags, sorted and deduplicated with mcp[cli]."""
assert update_claude_config(file_spec="s.py:app", server_name="s", with_packages=["zebra", "aardvark", "zebra"])
args = _read_server(config_dir, "s")["args"]
assert args[:8] == ["run", "--frozen", "--with", "aardvark", "--with", "mcp[cli]", "--with", "zebra"]
def test_with_editable_adds_flag(config_dir: Path, tmp_path: Path):
"""with_editable should add --with-editable after the --with flags."""
editable = tmp_path / "project"
assert update_claude_config(file_spec="s.py:app", server_name="s", with_editable=editable)
args = _read_server(config_dir, "s")["args"]
assert args[4:6] == ["--with-editable", str(editable)]
def test_env_vars_written(config_dir: Path):
"""env_vars should be written under the server's env key."""
assert update_claude_config(file_spec="s.py:app", server_name="s", env_vars={"KEY": "val"})
assert _read_server(config_dir, "s")["env"] == {"KEY": "val"}
def test_existing_env_vars_merged_new_wins(config_dir: Path):
"""Re-installing should merge env vars, with new values overriding existing ones."""
(config_dir / "claude_desktop_config.json").write_text(
json.dumps({"mcpServers": {"s": {"env": {"OLD": "keep", "KEY": "old"}}}})
)
assert update_claude_config(file_spec="s.py:app", server_name="s", env_vars={"KEY": "new"})
assert _read_server(config_dir, "s")["env"] == {"OLD": "keep", "KEY": "new"}
def test_existing_env_vars_preserved_without_new(config_dir: Path):
"""Re-installing without env_vars should keep the existing env block intact."""
(config_dir / "claude_desktop_config.json").write_text(json.dumps({"mcpServers": {"s": {"env": {"KEEP": "me"}}}}))
assert update_claude_config(file_spec="s.py:app", server_name="s")
assert _read_server(config_dir, "s")["env"] == {"KEEP": "me"}
def test_other_servers_preserved(config_dir: Path):
"""Installing a new server should not clobber existing mcpServers entries."""
(config_dir / "claude_desktop_config.json").write_text(json.dumps({"mcpServers": {"other": {"command": "x"}}}))
assert update_claude_config(file_spec="s.py:app", server_name="s")
config = json.loads((config_dir / "claude_desktop_config.json").read_text())
assert set(config["mcpServers"]) == {"other", "s"}
assert config["mcpServers"]["other"] == {"command": "x"}
def test_raises_when_config_dir_missing(monkeypatch: pytest.MonkeyPatch):
"""Should raise RuntimeError when Claude Desktop config dir can't be found."""
monkeypatch.setattr("mcp.cli.claude.get_claude_config_path", lambda: None)
monkeypatch.setattr("mcp.cli.claude.get_uv_path", lambda: "/fake/bin/uv")
with pytest.raises(RuntimeError, match="Claude Desktop config directory not found"):
update_claude_config(file_spec="s.py:app", server_name="s")
@pytest.mark.parametrize("which_result, expected", [("/usr/local/bin/uv", "/usr/local/bin/uv"), (None, "uv")])
def test_get_uv_path(monkeypatch: pytest.MonkeyPatch, which_result: str | None, expected: str):
"""Should return shutil.which's result, or fall back to bare 'uv' when not on PATH."""
def fake_which(cmd: str) -> str | None:
return which_result
monkeypatch.setattr("shutil.which", fake_which)
assert get_uv_path() == expected
@pytest.mark.parametrize(
"file_spec, expected_last_arg",
[
("C:\\Users\\server.py", "C:\\Users\\server.py"),
("C:\\Users\\server.py:app", "C:\\Users\\server.py:app"),
],
)
def test_windows_drive_letter_not_split(
config_dir: Path, monkeypatch: pytest.MonkeyPatch, file_spec: str, expected_last_arg: str
):
"""Drive-letter paths like 'C:\\server.py' must not be split on the drive colon.
Before the fix, a bare 'C:\\path\\server.py' would hit rsplit(":", 1) and yield
("C", "\\path\\server.py"), calling resolve() on Path("C") instead of the full path.
"""
seen: list[str] = []
def fake_resolve(self: Path) -> Path:
seen.append(str(self))
return self
monkeypatch.setattr(Path, "resolve", fake_resolve)
assert update_claude_config(file_spec=file_spec, server_name="s")
assert seen == ["C:\\Users\\server.py"]
assert _read_server(config_dir, "s")["args"][-1] == expected_last_arg

75
tests/client/test_config.py
View file

@ -1,75 +0,0 @@
import json
import subprocess
from pathlib import Path
from unittest.mock import patch
import pytest
from mcp.cli.claude import update_claude_config
@pytest.fixture
def temp_config_dir(tmp_path: Path):
"""Create a temporary Claude config directory."""
config_dir = tmp_path / "Claude"
config_dir.mkdir()
return config_dir
@pytest.fixture
def mock_config_path(temp_config_dir: Path):
"""Mock get_claude_config_path to return our temporary directory."""
with patch("mcp.cli.claude.get_claude_config_path", return_value=temp_config_dir):
yield temp_config_dir
def test_command_execution(mock_config_path: Path):
"""Test that the generated command can actually be executed."""
# Setup
server_name = "test_server"
file_spec = "test_server.py:app"
# Update config
success = update_claude_config(file_spec=file_spec, server_name=server_name)
assert success
# Read the generated config
config_file = mock_config_path / "claude_desktop_config.json"
config = json.loads(config_file.read_text())
# Get the command and args
server_config = config["mcpServers"][server_name]
command = server_config["command"]
args = server_config["args"]
test_args = [command] + args + ["--help"]
result = subprocess.run(test_args, capture_output=True, text=True, timeout=20, check=False)
assert result.returncode == 0
assert "usage" in result.stdout.lower()
def test_absolute_uv_path(mock_config_path: Path):
"""Test that the absolute path to uv is used when available."""
# Mock the shutil.which function to return a fake path
mock_uv_path = "/usr/local/bin/uv"
with patch("mcp.cli.claude.get_uv_path", return_value=mock_uv_path):
# Setup
server_name = "test_server"
file_spec = "test_server.py:app"
# Update config
success = update_claude_config(file_spec=file_spec, server_name=server_name)
assert success
# Read the generated config
config_file = mock_config_path / "claude_desktop_config.json"
config = json.loads(config_file.read_text())
# Verify the command is the absolute path
server_config = config["mcpServers"][server_name]
command = server_config["command"]
assert command == mock_uv_path