Uses importlib.metadata in favor of pkg_resources

cerberus/__init__.py

@@ -10,16 +10,15 @@
 
 from __future__ import absolute_import
 
-from pkg_resources import get_distribution, DistributionNotFound
-
-from cerberus.validator import DocumentError, Validator
+from cerberus.platform import importlib_metadata
 from cerberus.schema import rules_set_registry, schema_registry, SchemaError
 from cerberus.utils import TypeDefinition
+from cerberus.validator import DocumentError, Validator
 
 
 try:
-    __version__ = get_distribution("Cerberus").version
-except DistributionNotFound:
+    __version__ = importlib_metadata.version("Cerberus")
+except importlib_metadata.PackageNotFoundError:
     __version__ = "unknown"
 
 __all__ = [
@@ -29,4 +28,5 @@
     Validator.__name__,
     "schema_registry",
     "rules_set_registry",
+    "__version__",
 ]

cerberus/platform.py

@@ -10,15 +10,15 @@
 
 
 if PYTHON_VERSION < 3:
-    _str_type = basestring  # noqa: F821
     _int_types = (int, long)  # noqa: F821
+    _str_type = basestring  # noqa: F821
 else:
-    _str_type = str
     _int_types = (int,)
+    _str_type = str
 
 
 if PYTHON_VERSION < 3.3:
-    from collections import (  # noqa: F401
+    from collections import (
         Callable,
         Container,
         Hashable,
@@ -30,7 +30,7 @@
         Sized,
     )
 else:
-    from collections.abc import (  # noqa: F401
+    from collections.abc import (
         Callable,
         Container,
         Hashable,
@@ -41,3 +41,24 @@
         Set,
         Sized,
     )
+
+if PYTHON_VERSION < 3.8:
+    import importlib_metadata
+else:
+    import importlib.metadata as importlib_metadata
+
+
+__all__ = (
+    "_int_types",
+    "_str_type",
+    "importlib_metadata",
+    Callable.__name__,
+    Container.__name__,
+    Hashable.__name__,
+    Iterable.__name__,
+    Mapping.__name__,
+    MutableMapping.__name__,
+    Sequence.__name__,
+    Set.__name__,
+    Sized.__name__,
+)

cerberus/tests/test_assorted.py

@@ -1,15 +1,14 @@
 # -*- coding: utf-8 -*-
 
 from decimal import Decimal
-from pkg_resources import Distribution, DistributionNotFound
 
 from pytest import mark
 
 from cerberus import TypeDefinition, Validator
 from cerberus.tests import assert_fail, assert_success
 from cerberus.utils import validator_factory
 from cerberus.validator import BareValidator
-from cerberus.platform import PYTHON_VERSION
+from cerberus.platform import PYTHON_VERSION, importlib_metadata
 
 
 if PYTHON_VERSION > 3 and PYTHON_VERSION < 3.4:
@@ -21,23 +20,25 @@
 
 
 def test_pkgresources_version(monkeypatch):
-    def create_fake_distribution(name):
-        return Distribution(project_name="cerberus", version="1.2.3")
+    def return_fake_version(name):
+        assert name == "Cerberus"
+        return "1.2.3"
 
     with monkeypatch.context() as m:
         cerberus = __import__("cerberus")
-        m.setattr("pkg_resources.get_distribution", create_fake_distribution)
+        m.setattr("cerberus.importlib_metadata.version", return_fake_version)
         reload(cerberus)
         assert cerberus.__version__ == "1.2.3"
 
 
 def test_version_not_found(monkeypatch):
-    def raise_distribution_not_found(name):
-        raise DistributionNotFound("pkg_resources cannot get distribution")
+    def raise_package_not_found_error(name):
+        assert name == "Cerberus"
+        raise importlib_metadata.PackageNotFoundError
 
     with monkeypatch.context() as m:
         cerberus = __import__("cerberus")
-        m.setattr("pkg_resources.get_distribution", raise_distribution_not_found)
+        m.setattr("cerberus.importlib_metadata.version", raise_package_not_found_error)
         reload(cerberus)
         assert cerberus.__version__ == "unknown"
 

setup.py

@@ -40,7 +40,7 @@
     setup_requires=setup_requires,
     tests_require=["pytest"],
     test_suite="cerberus.tests",
-    install_requires=["setuptools"],
+    install_requires=["importlib-metadata; python_version < '3.8'"],
     keywords=["validation", "schema", "dictionaries", "documents", "normalization"],
     python_requires=">=2.7",
     classifiers=[