[stable-2.12] ansible-test - Adjust unit test mock usage. (#78003)

* ansible-test - Prefer unittest.mock for core.

(cherry picked from commit 81351022d8d1c0133b47af57f993f4e82f6c1a67)

* ansible-test - Adjust unit test mock usage. (#77961)

(cherry picked from commit 23914d3f0b5d69e7710c3744f373203c8caa6693)

5 files changed, 26 insertions, 10 deletions

diff --git a/changelogs/fragments/ansible-test-ansible-core-mock.yml b/changelogs/fragments/ansible-test-ansible-core-mock.yml
new file mode 100644
index 0000000000..60ea2d25fd
--- /dev/null
+++ b/changelogs/fragments/ansible-test-ansible-core-mock.yml
@@ -0,0 +1,2 @@
+minor_changes:
+  - ansible-test - Avoid using the ``mock_use_standalone_module`` setting for unit tests running on Python 3.8 or later.
diff --git a/test/lib/ansible_test/_data/pytest.ini b/test/lib/ansible_test/_data/pytest.ini
deleted file mode 100644
index c1c38ff786..0000000000
--- a/test/lib/ansible_test/_data/pytest.ini
+++ /dev/null
@@ -1,9 +0,0 @@
-[pytest]
-xfail_strict = true
-mock_use_standalone_module = true
-# It was decided to stick with "legacy" (aka "xunit1") for now.
-# Currently used pytest versions all support xunit2 format too.
-# Except the one used under Python 2.6 - it doesn't process this option
-# at all. Ref:
-# https://github.com/ansible/ansible/pull/66445#discussion_r372530176
-junit_family = xunit1
diff --git a/test/lib/ansible_test/_data/pytest/config/default.ini b/test/lib/ansible_test/_data/pytest/config/default.ini
new file mode 100644
index 0000000000..60575bfe32
--- /dev/null
+++ b/test/lib/ansible_test/_data/pytest/config/default.ini
@@ -0,0 +1,4 @@
+[pytest]
+xfail_strict = true
+# avoid using 'mock_use_standalone_module = true' so package maintainers can avoid packaging 'mock'
+junit_family = xunit1
diff --git a/test/lib/ansible_test/_data/pytest/config/legacy.ini b/test/lib/ansible_test/_data/pytest/config/legacy.ini
new file mode 100644
index 0000000000..b2668dc287
--- /dev/null
+++ b/test/lib/ansible_test/_data/pytest/config/legacy.ini
@@ -0,0 +1,4 @@
+[pytest]
+xfail_strict = true
+mock_use_standalone_module = true
+junit_family = xunit1
diff --git a/test/lib/ansible_test/_internal/commands/units/__init__.py b/test/lib/ansible_test/_internal/commands/units/__init__.py
index 9a2b182754..995f715937 100644
--- a/test/lib/ansible_test/_internal/commands/units/__init__.py
+++ b/test/lib/ansible_test/_internal/commands/units/__init__.py
@@ -21,6 +21,7 @@ from ...util import (
     ANSIBLE_TEST_DATA_ROOT,
     display,
     is_subdir,
+    str_to_version,
     SubprocessError,
     ANSIBLE_LIB_ROOT,
     ANSIBLE_TEST_TARGET_ROOT,
@@ -235,6 +236,20 @@ def command_units(args):  # type: (UnitsConfig) -> None
         sys.exit()
 
     for test_context, python, paths, env in test_sets:
+        # When using pytest-mock, make sure that features introduced in Python 3.8 are available to older Python versions.
+        # This is done by enabling the mock_use_standalone_module feature, which forces use of mock even when unittest.mock is available.
+        # Later Python versions have not introduced additional unittest.mock features, so use of mock is not needed as of Python 3.8.
+        # If future Python versions introduce new unittest.mock features, they will not be available to older Python versions.
+        # Having the cutoff at Python 3.8 also eases packaging of ansible-core since no supported controller version requires the use of mock.
+        #
+        # NOTE: This only affects use of pytest-mock.
+        #       Collection unit tests may directly import mock, which will be provided by ansible-test when it installs requirements using pip.
+        #       Although mock is available for ansible-core unit tests, they should import units.compat.mock instead.
+        if str_to_version(python.version) < (3, 8):
+            config_name = 'legacy.ini'
+        else:
+            config_name = 'default.ini'
+
         cmd = [
             'pytest',
             '--forked',
@@ -243,7 +258,7 @@ def command_units(args):  # type: (UnitsConfig) -> None
             '--color',
             'yes' if args.color else 'no',
             '-p', 'no:cacheprovider',
-            '-c', os.path.join(ANSIBLE_TEST_DATA_ROOT, 'pytest.ini'),
+            '-c', os.path.join(ANSIBLE_TEST_DATA_ROOT, 'pytest', 'config', config_name),
             '--junit-xml', os.path.join(ResultType.JUNIT.path, 'python%s-%s-units.xml' % (python.version, test_context)),
         ]