fix: Extract 'matches if specified' logic

mybox/package/base.py

@@ -8,7 +8,7 @@
 from ..parallel import gather_
 from ..state import DB
 from ..tracker import Tracker
-from ..utils import allow_singular, async_cached
+from ..utils import allow_singular, async_cached, matches_if_specified
 
 
 class Package(BaseModel, ABC):
@@ -63,12 +63,9 @@ async def install(self, *, tracker: Tracker) -> None:
         pass
 
     async def applicable(self) -> bool:
-        def check_os(name: str) -> bool:
-            return self.os is None or name in self.os
-
         os = await self.driver.os()
         return os.switch_(
-            linux=lambda linux: check_os("linux")
-            and (self.distribution is None or linux.distribution in self.distribution),
-            macos=lambda: check_os("darwin"),
+            linux=lambda linux: matches_if_specified(self.os, "linux")
+            and matches_if_specified(self.distribution, linux.distribution),
+            macos=lambda: matches_if_specified(self.os, "darwin"),
         )

mybox/utils.py

@@ -35,6 +35,10 @@ def allow_singular_none(field: str) -> Any:
     return field_validator(field, mode="before")(lambda cls, x: unsome(x))
 
 
+def matches_if_specified(possibilities: Optional[list[T]], value: T) -> bool:
+    return possibilities is None or value in possibilities
+
+
 def intercalate(delimiter: T, items: Iterable[Iterable[T]]) -> list[T]:
     it = iter(items)
     try:

tests/test_utils.py

@@ -1,6 +1,12 @@
 import pytest
 
-from mybox.utils import flatten, intercalate, run_ok, with_extensions
+from mybox.utils import (
+    flatten,
+    intercalate,
+    matches_if_specified,
+    run_ok,
+    with_extensions,
+)
 
 
 class TestRunOK:
@@ -39,3 +45,10 @@ def test_with_extensions():
     extensions = ["com", "exe"]
     assert with_extensions("foo", extensions) == ["foo.com", "foo.exe"]
     assert with_extensions("foo.com", extensions) == ["foo.com"]
+
+
+def test_matches_if_specified():
+    assert matches_if_specified(None, "anything")
+    assert not matches_if_specified([], "anything")
+    assert matches_if_specified(["alpha", "beta"], "alpha")
+    assert not matches_if_specified(["alpha", "beta"], "gamma")