Fix module name retrieval in backend.plugins.remove_duplicates(), plugin tests (#5959)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: kmuehlbauer

doc/whats-new.rst

@@ -36,6 +36,8 @@ Bug fixes
 ~~~~~~~~~
 - Fix plot.line crash for data of shape ``(1, N)`` in _title_for_slice on format_item (:pull:`5948`).
   By `Sebastian Weigand <https://github.com/s-weigand>`_.
+- Fix a regression in the removal of duplicate backend entrypoints (:issue:`5944`, :pull:`5959`)
+  By `Kai Mühlbauer <https://github.com/kmuehlbauer>`_.
 
 Documentation
 ~~~~~~~~~~~~~
@@ -49,6 +51,10 @@ Documentation
 Internal Changes
 ~~~~~~~~~~~~~~~~
 
+- Use ``importlib`` to replace functionality of ``pkg_resources`` in
+  backend plugins tests. (:pull:`5959`).
+  By `Kai Mühlbauer <https://github.com/kmuehlbauer>`_.
+
 
 .. _whats-new.0.20.1:
 

xarray/backends/plugins.py

@@ -23,15 +23,17 @@ def remove_duplicates(entrypoints):
     # check if there are multiple entrypoints for the same name
     unique_entrypoints = []
     for name, matches in entrypoints_grouped:
-        matches = list(matches)
+        # remove equal entrypoints
+        matches = list(set(matches))
         unique_entrypoints.append(matches[0])
         matches_len = len(matches)
         if matches_len > 1:
-            selected_module_name = matches[0].module_name
-            all_module_names = [e.module_name for e in matches]
+            all_module_names = [e.value.split(":")[0] for e in matches]
+            selected_module_name = all_module_names[0]
             warnings.warn(
                 f"Found {matches_len} entrypoints for the engine name {name}:"
-                f"\n {all_module_names}.\n It will be used: {selected_module_name}.",
+                f"\n {all_module_names}.\n "
+                f"The entrypoint {selected_module_name} will be used.",
                 RuntimeWarning,
             )
     return unique_entrypoints

xarray/tests/test_plugins.py

@@ -1,10 +1,20 @@
+import sys
 from unittest import mock
 
-import pkg_resources
 import pytest
 
 from xarray.backends import common, plugins
 
+if sys.version_info >= (3, 8):
+    from importlib.metadata import EntryPoint
+
+    importlib_metadata_mock = "importlib.metadata"
+else:
+    # if the fallback library is missing, we are doomed.
+    from importlib_metadata import EntryPoint
+
+    importlib_metadata_mock = "importlib_metadata"
+
 
 class DummyBackendEntrypointArgs(common.BackendEntrypoint):
     def open_dataset(filename_or_obj, *args):
@@ -29,12 +39,12 @@ def open_dataset(self, filename_or_obj, *, decoder):
 @pytest.fixture
 def dummy_duplicated_entrypoints():
     specs = [
-        "engine1 = xarray.tests.test_plugins:backend_1",
-        "engine1 = xarray.tests.test_plugins:backend_2",
-        "engine2 = xarray.tests.test_plugins:backend_1",
-        "engine2 = xarray.tests.test_plugins:backend_2",
+        ["engine1", "xarray.tests.test_plugins:backend_1", "xarray.backends"],
+        ["engine1", "xarray.tests.test_plugins:backend_2", "xarray.backends"],
+        ["engine2", "xarray.tests.test_plugins:backend_1", "xarray.backends"],
+        ["engine2", "xarray.tests.test_plugins:backend_2", "xarray.backends"],
     ]
-    eps = [pkg_resources.EntryPoint.parse(spec) for spec in specs]
+    eps = [EntryPoint(name, value, group) for name, value, group in specs]
     return eps
 
 
@@ -46,8 +56,10 @@ def test_remove_duplicates(dummy_duplicated_entrypoints) -> None:
 
 
 def test_broken_plugin() -> None:
-    broken_backend = pkg_resources.EntryPoint.parse(
-        "broken_backend = xarray.tests.test_plugins:backend_1"
+    broken_backend = EntryPoint(
+        "broken_backend",
+        "xarray.tests.test_plugins:backend_1",
+        "xarray.backends",
     )
     with pytest.warns(RuntimeWarning) as record:
         _ = plugins.build_engines([broken_backend])
@@ -68,13 +80,15 @@ def test_remove_duplicates_warnings(dummy_duplicated_entrypoints) -> None:
     assert "entrypoints" in message1
 
 
-@mock.patch("pkg_resources.EntryPoint.load", mock.MagicMock(return_value=None))
+@mock.patch(
+    f"{importlib_metadata_mock}.EntryPoint.load", mock.MagicMock(return_value=None)
+)
 def test_backends_dict_from_pkg() -> None:
     specs = [
-        "engine1 = xarray.tests.test_plugins:backend_1",
-        "engine2 = xarray.tests.test_plugins:backend_2",
+        ["engine1", "xarray.tests.test_plugins:backend_1", "xarray.backends"],
+        ["engine2", "xarray.tests.test_plugins:backend_2", "xarray.backends"],
     ]
-    entrypoints = [pkg_resources.EntryPoint.parse(spec) for spec in specs]
+    entrypoints = [EntryPoint(name, value, group) for name, value, group in specs]
     engines = plugins.backends_dict_from_pkg(entrypoints)
     assert len(engines) == 2
     assert engines.keys() == set(("engine1", "engine2"))
@@ -114,12 +128,12 @@ def test_set_missing_parameters_raise_error() -> None:
 
 
 @mock.patch(
-    "pkg_resources.EntryPoint.load",
+    f"{importlib_metadata_mock}.EntryPoint.load",
     mock.MagicMock(return_value=DummyBackendEntrypoint1),
 )
 def test_build_engines() -> None:
-    dummy_pkg_entrypoint = pkg_resources.EntryPoint.parse(
-        "cfgrib = xarray.tests.test_plugins:backend_1"
+    dummy_pkg_entrypoint = EntryPoint(
+        "cfgrib", "xarray.tests.test_plugins:backend_1", "xarray_backends"
     )
     backend_entrypoints = plugins.build_engines([dummy_pkg_entrypoint])
 
@@ -131,17 +145,13 @@ def test_build_engines() -> None:
 
 
 @mock.patch(
-    "pkg_resources.EntryPoint.load",
+    f"{importlib_metadata_mock}.EntryPoint.load",
     mock.MagicMock(return_value=DummyBackendEntrypoint1),
 )
 def test_build_engines_sorted() -> None:
     dummy_pkg_entrypoints = [
-        pkg_resources.EntryPoint.parse(
-            "dummy2 = xarray.tests.test_plugins:backend_1",
-        ),
-        pkg_resources.EntryPoint.parse(
-            "dummy1 = xarray.tests.test_plugins:backend_1",
-        ),
+        EntryPoint("dummy2", "xarray.tests.test_plugins:backend_1", "xarray.backends"),
+        EntryPoint("dummy1", "xarray.tests.test_plugins:backend_1", "xarray.backends"),
     ]
     backend_entrypoints = plugins.build_engines(dummy_pkg_entrypoints)
     backend_entrypoints = list(backend_entrypoints)