Test reorganization and cleanup. (#18270)

- Correct directory name in test/README.md
- Move code-smell tests to test/sanity/code-smell
- Update code-smell.sh to use new script paths
- Add test/integration/target-prefixes.win for ansible-test
- Move module unit tests to match module directory layout

test/units/modules/core/cloud/docker/test_docker.py

@@ -0,0 +1,19 @@
+import collections
+import os
+import unittest
+
+from ansible.modules.core.cloud.docker._docker import get_split_image_tag
+
+class DockerSplitImageTagTestCase(unittest.TestCase):
+
+    def test_trivial(self):
+        self.assertEqual(get_split_image_tag('test'), ('test', 'latest'))
+
+    def test_with_org_name(self):
+        self.assertEqual(get_split_image_tag('ansible/centos7-ansible'), ('ansible/centos7-ansible', 'latest'))
+
+    def test_with_tag(self):
+        self.assertEqual(get_split_image_tag('test:devel'), ('test', 'devel'))
+
+    def test_with_tag_and_org_name(self):
+        self.assertEqual(get_split_image_tag('ansible/centos7-ansible:devel'), ('ansible/centos7-ansible', 'devel'))