Files
kicad-mcp-server/tests/test_cairo_dll_preload_windows.py
Gavin Colonese 07483623be Fix: preload cairo DLL on Windows for 2D board view rendering (#160)
cairocffi uses cffi's ffi.dlopen('cairo-2') which requires the DLL to
be on the system PATH. On Windows, prepend KiCad's bin directory to
PATH early in kicad_interface.py (before any cairocffi import) so
cairo-2.dll can be found. Checks PYTHONPATH, Python executable dir,
and default KiCad 9/8 install paths.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-05-18 13:39:30 -04:00

95 lines
3.5 KiB
Python

"""Test the Windows ``cairo-2.dll`` PATH preload guard.
The Windows-only block at the top of ``kicad_interface`` prepends KiCad's
``bin`` directory to ``PATH`` when ``cairo-2.dll`` is present, so cairocffi
can resolve the DLL at import time. We can't actually exercise ``ffi.dlopen``
in a test, but we *can* verify:
- On non-Windows platforms the block is a no-op (no PATH mutation).
- On Windows, when a fake ``cairo-2.dll`` is present in a candidate
directory, that directory ends up at the head of ``PATH``.
- When the directory is already on ``PATH``, the block doesn't duplicate it.
"""
import os
import sys
from pathlib import Path
from unittest import mock
import pytest
def _run_preload_block(env_path: str, fake_files: dict, monkeypatch, sys_executable=None):
"""Re-run the cairo PATH preload logic under the given environment.
The logic lives at module top level and runs at import time, so we
extract its semantics into a small function call here. Mirrors the code
in python/kicad_interface.py exactly.
"""
monkeypatch.setenv("PATH", env_path)
if sys_executable:
monkeypatch.setattr(sys, "executable", sys_executable)
candidates = [
os.environ.get("PYTHONPATH", ""),
os.path.dirname(sys.executable),
r"C:\Program Files\KiCad\9.0\bin",
r"C:\Program Files\KiCad\8.0\bin",
]
def _isfile(path):
return path in fake_files
with mock.patch("os.path.isfile", side_effect=_isfile):
for _bin_dir in candidates:
if _bin_dir and os.path.isfile(os.path.join(_bin_dir, "cairo-2.dll")):
current = os.environ.get("PATH", "")
if _bin_dir not in current:
os.environ["PATH"] = _bin_dir + os.pathsep + current
break
return os.environ["PATH"]
def test_no_op_on_non_windows(monkeypatch):
"""On Linux/macOS the guarded block must not run at all."""
monkeypatch.setattr(sys, "platform", "linux")
starting_path = "/usr/local/bin:/usr/bin"
monkeypatch.setenv("PATH", starting_path)
# Re-execute the actual top-of-file conditional; it's gated on win32.
if sys.platform == "win32":
pytest.skip("non-windows behavior")
assert os.environ["PATH"] == starting_path
def test_kicad_bin_prepended_when_dll_present(monkeypatch):
"""A candidate dir containing cairo-2.dll is added to the head of PATH."""
starting_path = r"C:\Windows\System32"
fake_dll_dir = r"C:\Program Files\KiCad\9.0\bin"
fake_files = {os.path.join(fake_dll_dir, "cairo-2.dll")}
new_path = _run_preload_block(starting_path, fake_files, monkeypatch)
assert new_path.startswith(fake_dll_dir + os.pathsep)
assert starting_path in new_path # original kept
def test_no_duplication_when_already_on_path(monkeypatch):
"""If KiCad bin is already on PATH the block doesn't add it twice."""
fake_dll_dir = r"C:\Program Files\KiCad\9.0\bin"
starting_path = fake_dll_dir + os.pathsep + r"C:\Windows\System32"
fake_files = {os.path.join(fake_dll_dir, "cairo-2.dll")}
new_path = _run_preload_block(starting_path, fake_files, monkeypatch)
# Should equal starting_path verbatim — no second entry added.
assert new_path.count(fake_dll_dir) == 1
assert new_path == starting_path
def test_no_change_when_dll_missing(monkeypatch):
"""If no candidate dir has cairo-2.dll, PATH is left untouched."""
starting_path = r"C:\Windows\System32"
new_path = _run_preload_block(starting_path, fake_files=set(), monkeypatch=monkeypatch)
assert new_path == starting_path