Merge branch 'bugfix/117-too-many-dists' into 'master'

Fix redundant dists from Fastpath.zip_children

Closes #117

See merge request python-devs/importlib_metadata!115

Author: jaraco

importlib_metadata/__init__.py

@@ -28,6 +28,7 @@
     MetaPathFinder,
     email_message_from_string,
     PyPy_repr,
+    unique_ordered,
     )
 from importlib import import_module
 from itertools import starmap
@@ -425,8 +426,8 @@ def zip_children(self):
         names = zip_path.root.namelist()
         self.joinpath = zip_path.joinpath
 
-        return (
-            posixpath.split(child)[0]
+        return unique_ordered(
+            child.split(posixpath.sep, 1)[0]
             for child in names
             )
 

importlib_metadata/_compat.py

@@ -15,9 +15,11 @@
     NotADirectoryError = builtins.NotADirectoryError
     PermissionError = builtins.PermissionError
     map = builtins.map
+    from itertools import filterfalse
 else:  # pragma: nocover
     from backports.configparser import ConfigParser
     from itertools import imap as map  # type: ignore
+    from itertools import ifilterfalse as filterfalse
     import contextlib2 as contextlib
     FileNotFoundError = IOError, OSError
     IsADirectoryError = IOError, OSError
@@ -131,3 +133,18 @@ def make_param(name):
     if affected:  # pragma: nocover
         __repr__ = __compat_repr__
     del affected
+
+
+# from itertools recipes
+def unique_everseen(iterable):  # pragma: nocover
+    "List unique elements, preserving order. Remember all elements ever seen."
+    seen = set()
+    seen_add = seen.add
+
+    for element in filterfalse(seen.__contains__, iterable):
+        seen_add(element)
+        yield element
+
+
+unique_ordered = (
+    unique_everseen if sys.version_info < (3, 7) else dict.fromkeys)

importlib_metadata/docs/changelog.rst

@@ -2,6 +2,12 @@
  importlib_metadata NEWS
 =========================
 
+v1.5.2
+======
+
+* Fix redundant entries from ``FastPath.zip_children``.
+  Closes #117.
+
 v1.5.1
 ======
 

importlib_metadata/tests/test_zip.py

@@ -1,7 +1,10 @@
 import sys
 import unittest
 
-from .. import distribution, entry_points, files, PackageNotFoundError, version
+from .. import (
+    distribution, entry_points, files, PackageNotFoundError,
+    version, distributions,
+    )
 
 try:
     from importlib.resources import path
@@ -52,6 +55,10 @@ def test_files(self):
             path = str(file.dist.locate_file(file))
             assert '.whl/' in path, path
 
+    def test_one_distribution(self):
+        dists = list(distributions(path=sys.path[:1]))
+        assert len(dists) == 1
+
 
 class TestEgg(TestZip):
     def setUp(self):