fix: remove dependency on packaging and pkg_resources (googleapis#852)

* fix: remove dependency on packaging and pkg_resources

* add test case

* lint

* update docstring

* add constraint for importlib_metadata

* address feedback

* address feedback

* remove comment

* address feedback

* address feedback

Author: parthea

google/api_core/_python_package_support.py

@@ -16,7 +16,7 @@
 
 import warnings
 import sys
-from typing import Optional
+from typing import Optional, Tuple
 
 from collections import namedtuple
 
@@ -25,7 +25,14 @@
     _get_distribution_and_import_packages,
 )
 
-from packaging.version import parse as parse_version
+if sys.version_info >= (3, 8):
+    from importlib import metadata
+else:
+    # TODO(https://github.com/googleapis/python-api-core/issues/835): Remove
+    # this code path once we drop support for Python 3.7
+    import importlib_metadata as metadata
+
+ParsedVersion = Tuple[int, ...]
 
 # Here we list all the packages for which we want to issue warnings
 # about deprecated and unsupported versions.
@@ -48,42 +55,56 @@
 UNKNOWN_VERSION_STRING = "--"
 
 
+def parse_version_to_tuple(version_string: str) -> ParsedVersion:
+    """Safely converts a semantic version string to a comparable tuple of integers.
+
+    Example: "4.25.8" -> (4, 25, 8)
+    Ignores non-numeric parts and handles common version formats.
+
+    Args:
+        version_string: Version string in the format "x.y.z" or "x.y.z<suffix>"
+
+    Returns:
+        Tuple of integers for the parsed version string.
+    """
+    parts = []
+    for part in version_string.split("."):
+        try:
+            parts.append(int(part))
+        except ValueError:
+            # If it's a non-numeric part (e.g., '1.0.0b1' -> 'b1'), stop here.
+            # This is a simplification compared to 'packaging.parse_version', but sufficient
+            # for comparing strictly numeric semantic versions.
+            break
+    return tuple(parts)
+
+
 def get_dependency_version(
     dependency_name: str,
 ) -> DependencyVersion:
     """Get the parsed version of an installed package dependency.
 
     This function checks for an installed package and returns its version
-    as a `packaging.version.Version` object for safe comparison. It handles
+    as a comparable tuple of integers object for safe comparison. It handles
     both modern (Python 3.8+) and legacy (Python 3.7) environments.
 
     Args:
         dependency_name: The distribution name of the package (e.g., 'requests').
 
     Returns:
-        A DependencyVersion namedtuple with `version` and
+        A DependencyVersion namedtuple with `version`  (a tuple of integers) and
         `version_string` attributes, or `DependencyVersion(None,
         UNKNOWN_VERSION_STRING)` if the package is not found or
         another error occurs during version discovery.
 
     """
     try:
-        if sys.version_info >= (3, 8):
-            from importlib import metadata
-
-            version_string = metadata.version(dependency_name)
-            return DependencyVersion(parse_version(version_string), version_string)
-
-        # TODO(https://github.com/googleapis/python-api-core/issues/835): Remove
-        # this code path once we drop support for Python 3.7
-        else:  # pragma: NO COVER
-            # Use pkg_resources, which is part of setuptools.
-            import pkg_resources
-
-            version_string = pkg_resources.get_distribution(dependency_name).version
-            return DependencyVersion(parse_version(version_string), version_string)
-
+        version_string: str = metadata.version(dependency_name)
+        parsed_version = parse_version_to_tuple(version_string)
+        return DependencyVersion(parsed_version, version_string)
     except Exception:
+        # Catch exceptions from metadata.version() (e.g., PackageNotFoundError)
+        # or errors during parse_version_to_tuple
         return DependencyVersion(None, UNKNOWN_VERSION_STRING)
 
 
@@ -132,10 +153,14 @@ def warn_deprecation_for_versions_less_than(
         or not minimum_fully_supported_version
     ):  # pragma: NO COVER
         return
+
     dependency_version = get_dependency_version(dependency_import_package)
     if not dependency_version.version:
         return
-    if dependency_version.version < parse_version(minimum_fully_supported_version):
+
+    if dependency_version.version < parse_version_to_tuple(
+        minimum_fully_supported_version
+    ):
         (
             dependency_package,
             dependency_distribution_package,

noxfile.py

@@ -127,6 +127,7 @@ def default(session, install_grpc=True, prerelease=False, install_async_rest=Fal
         "mock; python_version=='3.7'",
         "pytest",
         "pytest-cov",
+        "pytest-mock",
         "pytest-xdist",
     )
 

pyproject.toml

@@ -51,6 +51,9 @@ dependencies = [
   "proto-plus >= 1.25.0, < 2.0.0; python_version >= '3.13'",
   "google-auth >= 2.14.1, < 3.0.0",
   "requests >= 2.18.0, < 3.0.0",
+  # TODO(https://github.com/googleapis/python-api-core/issues/835): Remove
+  # `importlib_metadata` once we drop support for Python 3.7
+  "importlib_metadata>=1.4; python_version<'3.8'",
 ]
 dynamic = ["version"]
 

testing/constraints-3.7.txt

@@ -13,3 +13,4 @@ grpcio==1.33.2
 grpcio-status==1.33.2
 grpcio-gcp==0.2.2
 proto-plus==1.22.3
+importlib_metadata==1.4

tests/unit/test_python_package_support.py

@@ -14,12 +14,12 @@
 
 import sys
 import warnings
-from unittest.mock import patch, MagicMock
+from unittest.mock import patch
 
 import pytest
-from packaging.version import parse as parse_version
 
 from google.api_core._python_package_support import (
+    parse_version_to_tuple,
     get_dependency_version,
     warn_deprecation_for_versions_less_than,
     check_dependency_versions,
@@ -28,39 +28,28 @@
 )
 
 
-# TODO(https://github.com/googleapis/python-api-core/issues/835): Remove
-# this mark once we drop support for Python 3.7
-@pytest.mark.skipif(sys.version_info < (3, 8), reason="requires python3.8 or higher")
-@patch("importlib.metadata.version")
-def test_get_dependency_version_py38_plus(mock_version):
-    """Test get_dependency_version on Python 3.8+."""
-    mock_version.return_value = "1.2.3"
-    expected = DependencyVersion(parse_version("1.2.3"), "1.2.3")
+@pytest.mark.parametrize("version_string_to_test", ["1.2.3", "1.2.3b1"])
+def test_get_dependency_version(mocker, version_string_to_test):
+    """Test get_dependency_version."""
+    if sys.version_info >= (3, 8):
+        mock_importlib = mocker.patch(
+            "importlib.metadata.version", return_value=version_string_to_test
+        )
+    else:
+        # TODO(https://github.com/googleapis/python-api-core/issues/835): Remove
+        # `importlib_metadata` once we drop support for Python 3.7
+        mock_importlib = mocker.patch(
+            "importlib_metadata.version", return_value=version_string_to_test
+        )
+    expected = DependencyVersion(
+        parse_version_to_tuple(version_string_to_test), version_string_to_test
+    )
     assert get_dependency_version("some-package") == expected
-    mock_version.assert_called_once_with("some-package")
-
-    # Test package not found
-    mock_version.side_effect = ImportError
-    assert get_dependency_version("not-a-package") == DependencyVersion(None, "--")
-
 
-# TODO(https://github.com/googleapis/python-api-core/issues/835): Remove
-# this test function once we drop support for Python 3.7
-@pytest.mark.skipif(sys.version_info >= (3, 8), reason="requires python3.7")
-@patch("pkg_resources.get_distribution")
-def test_get_dependency_version_py37(mock_get_distribution):
-    """Test get_dependency_version on Python 3.7."""
-    mock_dist = MagicMock()
-    mock_dist.version = "4.5.6"
-    mock_get_distribution.return_value = mock_dist
-    expected = DependencyVersion(parse_version("4.5.6"), "4.5.6")
-    assert get_dependency_version("another-package") == expected
-    mock_get_distribution.assert_called_once_with("another-package")
+    mock_importlib.assert_called_once_with("some-package")
 
     # Test package not found
-    mock_get_distribution.side_effect = (
-        Exception  # pkg_resources has its own exception types
-    )
+    mock_importlib.side_effect = ImportError
     assert get_dependency_version("not-a-package") == DependencyVersion(None, "--")
 
 
@@ -74,7 +63,9 @@ def test_warn_deprecation_for_versions_less_than(mock_get_version, mock_get_pack
         ("my-package (my.package)", "my-package"),
     ]
 
-    mock_get_version.return_value = DependencyVersion(parse_version("1.0.0"), "1.0.0")
+    mock_get_version.return_value = DependencyVersion(
+        parse_version_to_tuple("1.0.0"), "1.0.0"
+    )
     with pytest.warns(FutureWarning) as record:
         warn_deprecation_for_versions_less_than("my.package", "dep.package", "2.0.0")
     assert len(record) == 1
@@ -90,14 +81,14 @@ def test_warn_deprecation_for_versions_less_than(mock_get_version, mock_get_pack
         # Case 2: Installed version is equal to required, should not warn.
         mock_get_packages.reset_mock()
         mock_get_version.return_value = DependencyVersion(
-            parse_version("2.0.0"), "2.0.0"
+            parse_version_to_tuple("2.0.0"), "2.0.0"
         )
         warn_deprecation_for_versions_less_than("my.package", "dep.package", "2.0.0")
 
         # Case 3: Installed version is greater than required, should not warn.
         mock_get_packages.reset_mock()
         mock_get_version.return_value = DependencyVersion(
-            parse_version("3.0.0"), "3.0.0"
+            parse_version_to_tuple("3.0.0"), "3.0.0"
         )
         warn_deprecation_for_versions_less_than("my.package", "dep.package", "2.0.0")
 
@@ -115,7 +106,9 @@ def test_warn_deprecation_for_versions_less_than(mock_get_version, mock_get_pack
         ("dep-package (dep.package)", "dep-package"),
         ("my-package (my.package)", "my-package"),
     ]
-    mock_get_version.return_value = DependencyVersion(parse_version("1.0.0"), "1.0.0")
+    mock_get_version.return_value = DependencyVersion(
+        parse_version_to_tuple("1.0.0"), "1.0.0"
+    )
     template = "Custom warning for {dependency_package} used by {consumer_package}."
     with pytest.warns(FutureWarning) as record:
         warn_deprecation_for_versions_less_than(