Take .dist-info dir directly in wheel_metadata

Since retrieval of the .dist-info dir already ensures that a
distribution is found, this reduces responsibility on wheel_metadata and
lets us remove a few tests already covered by the tests for
test_wheel_dist_info_dir_*.

Author: chrahunt

src/pip/_internal/operations/install/wheel.py

@@ -315,7 +315,7 @@ def install_unpacked_wheel(
 
     try:
         info_dir = wheel_dist_info_dir(source, name)
-        metadata = wheel_metadata(wheeldir)
+        metadata = wheel_metadata(source, info_dir)
         version = wheel_version(metadata)
     except UnsupportedWheel as e:
         raise UnsupportedWheel(
@@ -658,27 +658,13 @@ def wheel_dist_info_dir(source, name):
     return info_dir
 
 
-def wheel_metadata(source_dir):
-    # type: (Optional[str]) -> Message
+def wheel_metadata(source, dist_info_dir):
+    # type: (str, str) -> Message
     """Return the WHEEL metadata of an extracted wheel, if possible.
     Otherwise, raise UnsupportedWheel.
     """
     try:
-        dists = [d for d in pkg_resources.find_on_path(None, source_dir)]
-    except Exception as e:
-        raise UnsupportedWheel(
-            "could not find a contained distribution due to: {!r}".format(e)
-        )
-
-    if not dists:
-        raise UnsupportedWheel("no contained distribution found")
-
-    dist = dists[0]
-
-    dist_info_dir = os.path.basename(dist.egg_info)
-
-    try:
-        with open(os.path.join(source_dir, dist_info_dir, "WHEEL"), "rb") as f:
+        with open(os.path.join(source, dist_info_dir, "WHEEL"), "rb") as f:
             wheel_text = ensure_str(f.read())
     except (IOError, OSError) as e:
         raise UnsupportedWheel("could not read WHEEL file: {!r}".format(e))

tests/unit/test_wheel.py

@@ -6,8 +6,7 @@
 from email import message_from_string
 
 import pytest
-from mock import Mock, patch
-from pip._vendor import pkg_resources
+from mock import patch
 from pip._vendor.packaging.requirements import Requirement
 
 from pip._internal.exceptions import UnsupportedWheel
@@ -224,27 +223,13 @@ def test_wheel_version_ok(tmpdir, data):
     ) == (1, 9)
 
 
-def test_wheel_metadata_fails_on_error(monkeypatch):
-    err = RuntimeError("example")
-    monkeypatch.setattr(pkg_resources, "find_on_path", Mock(side_effect=err))
-    with pytest.raises(UnsupportedWheel) as e:
-        wheel.wheel_metadata(".")
-    assert repr(err) in str(e.value)
-
-
-def test_wheel_metadata_fails_no_dists(tmpdir):
-    with pytest.raises(UnsupportedWheel) as e:
-        wheel.wheel_metadata(str(tmpdir))
-    assert "no contained distribution found" in str(e.value)
-
-
 def test_wheel_metadata_fails_missing_wheel(tmpdir):
     dist_info_dir = tmpdir / "simple-0.1.0.dist-info"
     dist_info_dir.mkdir()
     dist_info_dir.joinpath("METADATA").touch()
 
     with pytest.raises(UnsupportedWheel) as e:
-        wheel.wheel_metadata(str(tmpdir))
+        wheel.wheel_metadata(str(tmpdir), dist_info_dir.name)
     assert "could not read WHEEL file" in str(e.value)
 
 
@@ -256,7 +241,7 @@ def test_wheel_metadata_fails_on_bad_encoding(tmpdir):
     dist_info_dir.joinpath("WHEEL").write_bytes(b"\xff")
 
     with pytest.raises(UnsupportedWheel) as e:
-        wheel.wheel_metadata(str(tmpdir))
+        wheel.wheel_metadata(str(tmpdir), dist_info_dir.name)
     assert "error decoding WHEEL" in str(e.value)