Add regex support to gce_tag module, add unit tests and update integration test. (#19087)

The gce_tag module can support updating tags on multiple instances via an instance_pattern field.  Full Python regex is supported in the instance_pattern field.

'instance_pattern' and 'instance_name' are mutually exclusive and one must be specified.

The integration test for the gce_tag module has been updated to support the instance_pattern parameter.  Unit tests have been added to test the list-manipulation functionality.

Run the integration test with:

TEST_FLAGS='--tags "test_gce_tag"' make gce

Run the unit tests with:

python test/units/modules/cloud/google/test_gce_tag.py

test/units/modules/cloud/google/test_gce_tag.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python
+
+import unittest
+
+from ansible.modules.cloud.google.gce_tag import _get_changed_items, _intersect_items, _union_items
+
+class TestGCETag(unittest.TestCase):
+    """Unit tests for gce_tag module."""
+
+    def test_union_items(self):
+        """
+        Combine items in both lists
+        removing duplicates.
+        """
+        listA = [1, 2, 3, 4, 5, 8, 9]
+        listB = [1, 2, 3, 4, 5, 6, 7]
+        want = [1, 2, 3, 4, 5, 6, 7, 8, 9]
+        got = _union_items(listA, listB)
+        self.assertEqual(want, got)
+
+    def test_intersect_items(self):
+        """
+        All unique items from either list.
+        """
+        listA = [1, 2, 3, 4, 5, 8, 9]
+        listB = [1, 2, 3, 4, 5, 6, 7]
+        want = [1, 2, 3, 4, 5]
+        got = _intersect_items(listA, listB)
+        self.assertEqual(want, got)
+
+        # tags removed
+        new_tags = ['one', 'two']
+        existing_tags = ['two']
+        want = ['two'] # only remove the tag that was present
+        got = _intersect_items(existing_tags, new_tags)
+        self.assertEqual(want, got)
+
+    def test_get_changed_items(self):
+        """
+        All the items from left list that don't match
+        any item from the right list.
+        """
+        listA = [1, 2, 3, 4, 5, 8, 9]
+        listB = [1, 2, 3, 4, 5, 6, 7]
+        want = [8, 9]
+        got = _get_changed_items(listA, listB)
+        self.assertEqual(want, got)
+
+        # simulate new tags added
+        tags_to_add = ['one', 'two']
+        existing_tags = ['two']
+        want = ['one']
+        got = _get_changed_items(tags_to_add, existing_tags)
+        self.assertEqual(want, got)
+        
+        # simulate removing tags
+        # specifying one tag on right that doesn't exist
+        tags_to_remove = ['one', 'two']
+        existing_tags = ['two', 'three']
+        want = ['three']
+        got = _get_changed_items(existing_tags, tags_to_remove)
+        self.assertEqual(want, got)
+
+if __name__ == '__main__':
+    unittest.main()
+    
+
+