Use importlib.metadata first to avoid deprecation warnings (#878)

* Use importlib.metadata first to avoid deprecation warnings

* Use get distribution name of module before fetching its version

* Add support for Python versions < 3.9

* Fix conditional for packages_distributions

* Linter fixes

* Remove fixture in favor of test skips

---------

Co-authored-by: Lalleh Rafeei <84813886+lrafeei@users.noreply.github.com>

newrelic/common/package_version_utils.py

@@ -70,6 +70,23 @@ def int_or_str(value):
 def _get_package_version(name):
     module = sys.modules.get(name, None)
     version = None
+
+    # importlib was introduced into the standard library starting in Python3.8.
+    if "importlib" in sys.modules and hasattr(sys.modules["importlib"], "metadata"):
+        try:
+            # In Python3.10+ packages_distribution can be checked for as well
+            if hasattr(sys.modules["importlib"].metadata, "packages_distributions"):    # pylint: disable=E1101
+                distributions = sys.modules["importlib"].metadata.packages_distributions()  # pylint: disable=E1101
+                distribution_name = distributions.get(name, name)
+            else:
+                distribution_name = name
+
+            version = sys.modules["importlib"].metadata.version(distribution_name)  # pylint: disable=E1101
+            if version not in NULL_VERSIONS:
+                return version
+        except Exception:
+            pass
+
     for attr in VERSION_ATTRS:
         try:
             version = getattr(module, attr, None)
@@ -84,15 +101,6 @@ def _get_package_version(name):
         except Exception:
             pass
 
-    # importlib was introduced into the standard library starting in Python3.8.
-    if "importlib" in sys.modules and hasattr(sys.modules["importlib"], "metadata"):
-        try:
-            version = sys.modules["importlib"].metadata.version(name)  # pylint: disable=E1101
-            if version not in NULL_VERSIONS:
-                return version
-        except Exception:
-            pass
-
     if "pkg_resources" in sys.modules:
         try:
             version = sys.modules["pkg_resources"].get_distribution(name).version

tests/agent_unittests/test_package_version_utils.py

@@ -24,11 +24,19 @@
     get_package_version_tuple,
 )
 
+# Notes:
+# importlib.metadata was a provisional addition to the std library in PY38 and PY39
+# while pkg_resources was deprecated.
+# importlib.metadata is no longer provisional in PY310+.  It added some attributes
+# such as distribution_packages and removed pkg_resources.
+
 IS_PY38_PLUS = sys.version_info[:2] >= (3, 8)
+IS_PY310_PLUS = sys.version_info[:2] >= (3,10)
 SKIP_IF_NOT_IMPORTLIB_METADATA = pytest.mark.skipif(not IS_PY38_PLUS, reason="importlib.metadata is not supported.")
 SKIP_IF_IMPORTLIB_METADATA = pytest.mark.skipif(
     IS_PY38_PLUS, reason="importlib.metadata is preferred over pkg_resources."
 )
+SKIP_IF_NOT_PY310_PLUS = pytest.mark.skipif(not IS_PY310_PLUS, reason="These features were added in 3.10+")
 
 
 @pytest.fixture(scope="function", autouse=True)
@@ -38,8 +46,10 @@ def patched_pytest_module(monkeypatch):
             monkeypatch.delattr(pytest, attr)
 
     yield pytest
+
 
-
+# This test only works on Python 3.7
+@SKIP_IF_IMPORTLIB_METADATA
 @pytest.mark.parametrize(
     "attr,value,expected_value",
     (
@@ -58,6 +68,8 @@ def test_get_package_version(attr, value, expected_value):
     delattr(pytest, attr)
 
 
+# This test only works on Python 3.7
+@SKIP_IF_IMPORTLIB_METADATA
 def test_skips_version_callables():
     # There is no file/module here, so we monkeypatch
     # pytest instead for our purposes
@@ -72,6 +84,8 @@ def test_skips_version_callables():
     delattr(pytest, "version_tuple")
 
 
+# This test only works on Python 3.7
+@SKIP_IF_IMPORTLIB_METADATA
 @pytest.mark.parametrize(
     "attr,value,expected_value",
     (
@@ -97,6 +111,13 @@ def test_importlib_metadata():
     assert version not in NULL_VERSIONS, version
 
 
+@SKIP_IF_NOT_PY310_PLUS
+@validate_function_called("importlib.metadata", "packages_distributions")
+def test_mapping_import_to_distribution_packages():
+    version = get_package_version("pytest")
+    assert version not in NULL_VERSIONS, version
+
+
 @SKIP_IF_IMPORTLIB_METADATA
 @validate_function_called("pkg_resources", "get_distribution")
 def test_pkg_resources_metadata():