Make package finder return multiple directories

This doesn't change the implementation yet, but it prepares us for
supporting namespace packages passed in.

Author: seddonym

src/grimp/adaptors/packagefinder.py

@@ -12,7 +12,7 @@
 
 
 class ImportLibPackageFinder(AbstractPackageFinder):
-    def determine_package_directory(
+    def _determine_package_directory(
         self, package_name: str, file_system: AbstractFileSystem
     ) -> str:
         # TODO - do we need to add the current working directory here?
@@ -34,6 +34,11 @@ def determine_package_directory(
             "adding an __init__.py file should fix the problem."
         )
 
+    def determine_package_directories(
+        self, package_name: str, file_system: AbstractFileSystem
+    ) -> set[str]:
+        return {self._determine_package_directory(package_name, file_system)}
+
     def _is_a_package(self, spec: ModuleSpec, file_system: AbstractFileSystem) -> bool:
         assert spec.origin
         filename = file_system.split(spec.origin)[1]

src/grimp/application/ports/packagefinder.py

@@ -5,7 +5,7 @@
 
 class AbstractPackageFinder(abc.ABC):
     @abc.abstractmethod
-    def determine_package_directory(
+    def determine_package_directories(
         self, package_name: str, file_system: AbstractFileSystem
-    ) -> str:
+    ) -> set[str]:
         raise NotImplementedError

src/grimp/application/usecases.py

@@ -79,7 +79,7 @@ def _find_packages(
     found_packages: set[FoundPackage] = set()
 
     for package_name in package_names:
-        package_directory = package_finder.determine_package_directory(
+        [package_directory] = package_finder.determine_package_directories(
             package_name=package_name, file_system=file_system
         )
         found_package = module_finder.find_package(

tests/adaptors/packagefinder.py

@@ -5,7 +5,7 @@
 class BaseFakePackageFinder(AbstractPackageFinder):
     directory_map: dict[str, str] = {}
 
-    def determine_package_directory(
+    def determine_package_directories(
         self, package_name: str, file_system: AbstractFileSystem
-    ) -> str:
-        return self.directory_map[package_name]
+    ) -> set[str]:
+        return {self.directory_map[package_name]}

tests/unit/adaptors/test_packagefinder.py

@@ -25,10 +25,10 @@
         ),
     ),
 )
-def test_determine_package_directory(package, expected):
-    assert ImportLibPackageFinder().determine_package_directory(package, FileSystem()) == str(
-        expected
-    )
+def test_determine_package_directories(package, expected):
+    assert ImportLibPackageFinder().determine_package_directories(package, FileSystem()) == {
+        str(expected)
+    }
 
 
 def test_determine_package_directory_doesnt_support_namespace_packages():
@@ -40,7 +40,7 @@ def test_determine_package_directory_doesnt_support_namespace_packages():
             "namespace packages, adding an __init__.py file should fix the problem."
         ),
     ):
-        ImportLibPackageFinder().determine_package_directory("mynamespace", FakeFileSystem())
+        ImportLibPackageFinder().determine_package_directories("mynamespace", FakeFileSystem())
 
 
 @pytest.mark.parametrize(
@@ -53,8 +53,8 @@ def test_determine_package_directory_doesnt_support_namespace_packages():
         "mynamespace.yellow",
     ),
 )
-def test_determine_package_directory_doesnt_support_non_top_level_modules(package):
+def test_determine_package_directories_doesnt_support_non_top_level_modules(package):
     with pytest.raises(
         exceptions.NotATopLevelModule,
     ):
-        ImportLibPackageFinder().determine_package_directory(package, FakeFileSystem())
+        ImportLibPackageFinder().determine_package_directories(package, FakeFileSystem())