Make all doc fragments, module utils, and plugin utils private (#1144)

* Make all doc fragments, module utils, and plugin utils private.

* Remove some unused and no longer needed imports.

This hopefully also fixes the CI issues, which do not happen locally for me...

* Fix formatting.

* Try to make CI happy, again.

* Fix imports.

* Lint.

tests/unit/plugins/module_utils/test__image_archive.py

@@ -0,0 +1,91 @@
+# Copyright 2022 Red Hat | Ansible
+# GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+from __future__ import absolute_import, division, print_function
+
+
+__metaclass__ = type
+
+import tarfile
+
+import pytest
+from ansible_collections.community.docker.plugins.module_utils._image_archive import (
+    ImageArchiveInvalidException,
+    api_image_id,
+    archived_image_manifest,
+)
+
+from ..test_support.docker_image_archive_stubbing import (
+    write_imitation_archive,
+    write_imitation_archive_with_manifest,
+    write_irrelevant_tar,
+)
+
+
+@pytest.fixture
+def tar_file_name(tmpdir):
+    """
+    Return the name of a non-existing tar file in an existing temporary directory.
+    """
+
+    # Cast to str required by Python 2.x
+    return str(tmpdir.join("foo.tar"))
+
+
+@pytest.mark.parametrize(
+    "expected, value", [("sha256:foo", "foo"), ("sha256:bar", "bar")]
+)
+def test_api_image_id_from_archive_id(expected, value):
+    assert api_image_id(value) == expected
+
+
+def test_archived_image_manifest_extracts(tar_file_name):
+    expected_id = "abcde12345"
+    expected_tags = ["foo:latest", "bar:v1"]
+
+    write_imitation_archive(tar_file_name, expected_id, expected_tags)
+
+    actual = archived_image_manifest(tar_file_name)
+
+    assert actual.image_id == expected_id
+    assert actual.repo_tags == expected_tags
+
+
+def test_archived_image_manifest_extracts_nothing_when_file_not_present(tar_file_name):
+    image_id = archived_image_manifest(tar_file_name)
+
+    assert image_id is None
+
+
+def test_archived_image_manifest_raises_when_file_not_a_tar():
+    try:
+        archived_image_manifest(__file__)
+        raise AssertionError()
+    except ImageArchiveInvalidException as e:
+        assert isinstance(e.__cause__, tarfile.ReadError)
+        assert str(__file__) in str(e)
+
+
+def test_archived_image_manifest_raises_when_tar_missing_manifest(tar_file_name):
+    write_irrelevant_tar(tar_file_name)
+
+    try:
+        archived_image_manifest(tar_file_name)
+        raise AssertionError()
+    except ImageArchiveInvalidException as e:
+        assert isinstance(e.__cause__, KeyError)
+        assert "manifest.json" in str(e.__cause__)
+
+
+def test_archived_image_manifest_raises_when_manifest_missing_id(tar_file_name):
+    manifest = [{"foo": "bar"}]
+
+    write_imitation_archive_with_manifest(tar_file_name, manifest)
+
+    try:
+        archived_image_manifest(tar_file_name)
+        raise AssertionError()
+    except ImageArchiveInvalidException as e:
+        assert isinstance(e.__cause__, KeyError)
+        assert "Config" in str(e.__cause__)