Add test to demonstrate issue with symlinked packages

Author: jherland

tests/fixtures.py

@@ -169,6 +169,32 @@ def setUp(self):
         build_files(DistInfoPkg.files, self.site_dir)
 
 
+class DistInfoSymlinkedPkg(OnSysPath, SiteDir):
+    files: FilesSpec = {
+        "symlinked_pkg-1.0.0.dist-info": {
+            "METADATA": """
+                Name: symlinked-pkg
+                Version: 1.0.0
+                """,
+            "RECORD": "symlinked,,\n",
+        },
+        ".symlink.target": {
+            "__init__.py": """
+                def main():
+                    print("hello world")
+                """,
+        },
+        # "symlinked" -> ".symlink.target", see below
+    }
+
+    def setUp(self):
+        super().setUp()
+        build_files(DistInfoSymlinkedPkg.files, self.site_dir)
+        target = self.site_dir / ".symlink.target"
+        assert target.is_dir()
+        (self.site_dir / "symlinked").symlink_to(target, target_is_directory=True)
+
+
 class EggInfoPkg(OnSysPath, SiteDir):
     files: FilesSpec = {
         "egginfo_pkg.egg-info": {

tests/test_main.py

@@ -387,6 +387,32 @@ def test_packages_distributions_all_module_types(self):
         assert not any(name.endswith('.dist-info') for name in distributions)
 
 
+class PackagesDistributionsDistTest(
+    fixtures.DistInfoPkg,
+    fixtures.DistInfoSymlinkedPkg,
+    unittest.TestCase,
+):
+    def test_packages_distributions_on_dist_info(self):
+        """
+        Test _top_level_inferred() on various dist-info packages.
+        """
+        distributions = packages_distributions()
+
+        def import_names_from_package(package_name):
+            return {
+                import_name
+                for import_name, package_names in distributions.items()
+                if package_name in package_names
+            }
+
+        # distinfo-pkg has one import ('mod') inferred from RECORD
+        assert import_names_from_package('distinfo-pkg') == {'mod'}
+
+        # symlinked-pkg has one import ('symlinked') inderred from RECORD which
+        # references a symlink to the real package dir elsewhere.
+        assert import_names_from_package('symlinked-pkg') == {'symlinked'}
+
+
 class PackagesDistributionsEggTest(
     fixtures.EggInfoPkg,
     fixtures.EggInfoPkgPipInstalledNoToplevel,