add unit test for part_has_slices function

craft_parts/__init__.py

@@ -26,7 +26,7 @@
 from .features import Features
 from .infos import PartInfo, ProjectInfo, StepInfo
 from .lifecycle_manager import LifecycleManager
-from .parts import Part, part_has_overlay, validate_part
+from .parts import Part, part_has_overlay, part_has_slices, validate_part
 from .steps import Step
 
 __all__ = [
@@ -46,4 +46,5 @@
     "expand_environment",
     "validate_part",
     "part_has_overlay",
+    "part_has_slices",
 ]

craft_parts/parts.py

@@ -166,6 +166,15 @@ def has_overlay(self) -> bool:
             or self.overlay_files != ["*"]
         )
 
+    @property
+    def has_slices(self) -> bool:
+        """Whether the part has slices in its stage-packages.
+
+        :param data: The part data to query.
+        """
+        stage_packages = self.stage_packages or []
+        return any(name for name in stage_packages if is_slice(name))
+
 
 # pylint: disable=too-many-public-methods
 class Part:
@@ -639,14 +648,6 @@ def part_has_overlay(data: Dict[str, Any]) -> bool:
     return spec.has_overlay
 
 
-def part_has_slices(data: Dict[str, Any]) -> bool:
-    """Whether the part described by ``data`` has slices in its stage-packages.
-
-    :param data: The part data to query.
-    """
-    stage_packages = data.get("stage-packages", [])
-    return any(name for name in stage_packages if is_slice(name))
-
 
 def is_slice(name: str) -> bool:
     """Whether the stage-package is a slice or a package.

tests/unit/test_parts.py

@@ -339,6 +339,18 @@ def test_part_has_overlay(self, partitions):
         p = Part("foo", {}, partitions=partitions)
         assert p.has_overlay is False
 
+    @pytest.mark.parametrize(
+        ("tc_spec", "tc_result"),
+        [
+            ({}, False),
+            ({"stage-packages": ["libc6_libs"]}, True),
+            ({"stage-packages": ["python3"]}, False),
+        ],
+    )
+    def test_part_has_slices(self, partitions, tc_spec, tc_result):
+        p = Part("foo", tc_spec, partitions=partitions)
+        assert p.spec.has_slices == tc_result
+
 
 class TestPartOrdering:
     """Test part ordering.