diff --git a/oslo_policy/tests/test_sphinxext.py b/oslo_policy/tests/test_sphinxext.py
index 591b72ec..94493952 100644
--- a/oslo_policy/tests/test_sphinxext.py
+++ b/oslo_policy/tests/test_sphinxext.py
@@ -20,6 +20,36 @@ from oslo_policy import policy
 from oslo_policy import sphinxext
 
 
+class IndentTest(base.BaseTestCase):
+
+    def test_indent(self):
+        result = sphinxext._indent("foo\nbar")
+        self.assertEqual("    foo\n    bar", result)
+
+        result = sphinxext._indent("")
+        self.assertEqual("", result)
+
+        result = sphinxext._indent("\n")
+        self.assertEqual("\n", result)
+
+        result = sphinxext._indent("test\ntesting\n\nafter blank")
+        self.assertEqual("    test\n    testing\n\n    after blank", result)
+
+        result = sphinxext._indent("\tfoo\nbar")
+        self.assertEqual("    \tfoo\n    bar", result)
+
+        result = sphinxext._indent("    foo\nbar")
+        self.assertEqual("        foo\n    bar", result)
+
+        result = sphinxext._indent("foo\n    bar")
+        self.assertEqual("    foo\n        bar", result)
+
+        result = sphinxext._indent("foo\n\n    bar")
+        self.assertEqual("    foo\n\n        bar", result)
+
+        self.assertRaises(AttributeError, sphinxext._indent, None)
+
+
 class FormatPolicyTest(base.BaseTestCase):
 
     def test_minimal(self):