fix: tests during Nix build

Fixes the following error when executing the tests during a Nix build:

    Traceback (most recent call last):
      File "/build/inkstitch/lib/elements/element.py", line 714, in handle_unexpected_exceptions
        yield
      File "/build/inkstitch/lib/elements/element.py", line 650, in embroider
        stitch_groups = self._load_cached_stitch_groups(previous_stitch, next_element)
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/build/inkstitch/lib/debug/debug.py", line 172, in decorated
        result = func(*args, **kwargs)
                 ^^^^^^^^^^^^^^^^^^^^^
      File "/build/inkstitch/lib/elements/element.py", line 541, in _load_cached_stitch_groups
        stitch_groups = get_stitch_plan_cache().get(cache_key)
                        ^^^^^^^^^^^^^^^^^^^^^^^
      File "/build/inkstitch/lib/utils/cache.py", line 31, in get_stitch_plan_cache
        cache_dir = get_user_dir('cache')
                    ^^^^^^^^^^^^^^^^^^^^^
      File "/build/inkstitch/lib/utils/paths.py", line 50, in get_user_dir
        os.makedirs(path)
      File "<frozen os>", line 215, in makedirs
      File "<frozen os>", line 215, in makedirs
      File "<frozen os>", line 225, in makedirs
    PermissionError: [Errno 13] Permission denied: '/homeless-shelter'

2 files changed, 8 insertions, 11 deletions

diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 00000000..c4e58897
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,8 @@
+import pytest
+
+import lib.utils.settings
+
+@pytest.fixture(scope="session", autouse=True)
+def disable_cache():
+    # We disable the cache because Nix executes our tests with a non-writable HOME directory.
+    lib.utils.settings.global_settings._settings['cache_size'] = 0
diff --git a/tests/test_clone.py b/tests/test_clone.py
index 4b4cf101..ba6784e1 100644
--- a/tests/test_clone.py
+++ b/tests/test_clone.py
@@ -9,7 +9,6 @@ from inkex.tester.svg import svg
 from lib.commands import add_commands
 from lib.elements import Clone, EmbroideryElement, FillStitch
 from lib.svg.tags import INKSCAPE_LABEL, INKSTITCH_ATTRIBS, SVG_RECT_TAG
-from lib.utils import cache_module
 
 from .utils import element_count
 
@@ -22,16 +21,6 @@ def element_fill_angle(element: EmbroideryElement) -> Optional[float]:
 
 
 class CloneElementTest(TestCase):
-    # Monkey-patch the cahce to forcibly disable it: We may need to refactor this out for tests.
-    def setUp(self) -> None:
-        from pytest import MonkeyPatch
-        self.monkeypatch = MonkeyPatch()
-        self.monkeypatch.setattr(cache_module, "is_cache_disabled", lambda: True)
-
-    def tearDown(self) -> None:
-        self.monkeypatch.undo()
-        return super().tearDown()
-
     def assertAngleAlmostEqual(self, a, b) -> None:
         # Take the mod 180 of the returned angles, because e.g. -130deg and 50deg produce fills along the same angle.
         # We have to use a precision of 4 decimal digits because of the precision of the matrices as they are stored in the svg trees