Search weels for .dist-info directories

Some wheels don't use normalized names for their .dist-info directories,
so search the wheel for them.

Fixes: pypa#134

src/installer/sources.py

@@ -122,6 +122,22 @@ def open(cls, path: "os.PathLike[str]") -> Iterator["WheelFile"]:
         with zipfile.ZipFile(path) as f:
             yield cls(f)
 
+    @property
+    def dist_info_dir(self) -> str:
+        """Name of the dist-info directory."""
+        if not hasattr(self, "_dist_info_dir"):
+            top_level_directories = {
+                path.split("/", 1)[0] for path in self._zipfile.namelist()
+            }
+            dist_infos = [
+                name for name in top_level_directories if name.endswith(".dist-info")
+            ]
+            assert (
+                len(dist_infos) == 1
+            ), "Wheel doesn't contain exactly one .dist-info directory"
+            self._dist_info_dir = dist_infos[0]
+        return self._dist_info_dir
+
     @property
     def dist_info_filenames(self) -> List[str]:
         """Get names of all files in the dist-info directory."""

tests/test_sources.py

@@ -1,4 +1,5 @@
 import posixpath
+import textwrap
 import zipfile
 
 import pytest
@@ -92,3 +93,44 @@ def test_provides_correct_contents(self, fancy_wheel):
 
         assert sorted(got_records) == sorted(expected_records)
         assert got_files == files
+
+    def test_finds_dist_info(self, tmp_path):
+        # Create a wheel with a misnamed .dist-info
+        path = tmp_path / "denorm-1.0-py3-none-any.whl"
+        files = {
+            "denorm.py": b"",
+            "misnamed-1.0.0.dist-info/top_level.txt": b"""\
+                denorm
+            """,
+            "misnamed-1.0.0.dist-info/WHEEL": b"""\
+                Wheel-Version: 1.0
+                Generator: bad-magic (1.0.0)
+                Root-Is-Purelib: true
+                Tag: py3-none-any
+            """,
+            "misnamed-1.0.0.dist-info/METADATA": b"""\
+                Metadata-Version: 2.1
+                Name: denorm
+                Version: 1.0.0
+            """,
+            "misnamed-1.0.0.dist-info/RECORD": b"""\
+                fancy.py,,
+                misnamed-1.0.0.dist-info/top_level.txt,,
+                misnamed-1.0.0.dist-info/WHEEL,,
+                misnamed-1.0.0.dist-info/METADATA,,
+                misnamed-1.0.0.dist-info/RECORD,,
+            """,
+        }
+        with zipfile.ZipFile(path, "w") as archive:
+            for name, indented_content in files.items():
+                archive.writestr(
+                    name,
+                    textwrap.dedent(indented_content.decode("utf-8")).encode("utf-8"),
+                )
+        with WheelFile.open(path) as source:
+            assert sorted(source.dist_info_filenames) == [
+                "METADATA",
+                "RECORD",
+                "WHEEL",
+                "top_level.txt",
+            ]