Handle unavailable macOS version during backend selection

send2trash/mac/__init__.py

@@ -8,8 +8,9 @@
 from sys import version_info
 
 # NOTE: version of pyobjc only supports python >= 3.6 and 10.9+
-macos_ver = tuple(int(part) for part in mac_ver()[0].split("."))
-if version_info >= (3, 6) and macos_ver >= (10, 9):
+macos_ver_str = mac_ver()[0]
+macos_ver = tuple(int(part) for part in macos_ver_str.split(".")) if macos_ver_str else None
+if version_info >= (3, 6) and (macos_ver is None or macos_ver >= (10, 9)):
     try:
         from send2trash.mac.modern import send2trash
     except ImportError:

tests/test_plat_mac.py

@@ -0,0 +1,45 @@
+import runpy
+import sys
+import types
+from pathlib import Path
+
+import pytest
+
+
+SELECTOR = Path(__file__).parents[1] / "send2trash" / "mac" / "__init__.py"
+
+
+def select_backend(monkeypatch, version, modern_available=True):
+    modern = types.ModuleType("send2trash.mac.modern")
+    legacy = types.ModuleType("send2trash.mac.legacy")
+    modern.send2trash = object()
+    legacy.send2trash = object()
+
+    monkeypatch.setattr("platform.mac_ver", lambda: (version, ("", "", ""), ""))
+    monkeypatch.setitem(sys.modules, modern.__name__, modern if modern_available else None)
+    monkeypatch.setitem(sys.modules, legacy.__name__, legacy)
+
+    namespace = runpy.run_path(str(SELECTOR))
+    return namespace["send2trash"], {"modern": modern.send2trash, "legacy": legacy.send2trash}
+
+
+@pytest.mark.parametrize(
+    ("version", "expected"),
+    [
+        ("14.0", "modern"),
+        ("10.9", "modern"),
+        ("10.8", "legacy"),
+        ("", "modern"),
+    ],
+)
+def test_select_backend(monkeypatch, version, expected):
+    selected, backends = select_backend(monkeypatch, version)
+
+    assert selected is backends[expected]
+
+
+@pytest.mark.parametrize("version", ["14.0", ""])
+def test_modern_version_falls_back_when_modern_backend_is_unavailable(monkeypatch, version):
+    selected, backends = select_backend(monkeypatch, version, modern_available=False)
+
+    assert selected is backends["legacy"]