add test case for gh#333

Author: hendrikmuhs

python/tests/match_object_test.py

@@ -205,6 +205,7 @@ def test_get_value_string():
     c = StringDictionaryCompiler({"memory_limit_mb": "10"})
     c.add("abc", "aaaaa")
     c.add("abd", "bbbbb")
+    c.add("", "{}")
     with tmp_dictionary(c, "match_object_string.kv") as d:
         m = d["abc"]
         assert m.value == "aaaaa"
@@ -221,6 +222,10 @@ def test_get_value_string():
             )
             == "bbbbb"
         )
+        m = d["abd"]
+        # gh#333: keyvi < 0.6.4 returned a dictionary instead of a string
+        assert m.value == "{}"
+        assert isinstance(m.value, str)
 
 
 def test_matched_string():