Add unit test for oo_oreg_image filter

This commit adds unit test for filter to ensure it behaves
as expected.

roles/lib_utils/test/test_oo_filters.py

@@ -0,0 +1,37 @@
+'''
+ Unit tests for oo_filters
+'''
+import os
+import sys
+
+MODULE_PATH = os.path.realpath(os.path.join(__file__, os.pardir, os.pardir, 'filter_plugins'))
+sys.path.insert(0, MODULE_PATH)
+
+# pylint: disable=import-error,wrong-import-position,missing-docstring
+import oo_filters   # noqa: E402
+
+
+def test_lib_utils_oo_oreg_image():
+    default_url = "quay.io/coreos/etcd:v99"
+
+    oreg_url = "None"
+    output_image = oo_filters.lib_utils_oo_oreg_image(default_url, oreg_url)
+    assert output_image == default_url
+
+    oreg_url = "example.com/openshift/origin-${component}:${version}"
+    expected_output = "example.com/coreos/etcd:v99"
+    output_image = oo_filters.lib_utils_oo_oreg_image(default_url, oreg_url)
+    assert output_image == expected_output
+
+    oreg_url = "example.com/subdir/openshift/origin-${component}:${version}"
+    expected_output = "example.com/subdir/coreos/etcd:v99"
+    output_image = oo_filters.lib_utils_oo_oreg_image(default_url, oreg_url)
+    assert output_image == expected_output
+
+
+def main():
+    test_lib_utils_oo_oreg_image()
+
+
+if __name__ == '__main__':
+    main()