diff --git a/tests/pretty_printers.hpp b/tests/pretty_printers.hpp
index 86bd20d..3f592a5 100644
--- a/tests/pretty_printers.hpp
+++ b/tests/pretty_printers.hpp
@@ -36,4 +36,34 @@
     s << "}" << std::endl;
     return s;
 }
+
+std::ostream& operator<<(std::ostream& s, const yang::LeafDataType& type)
+{
+    s << std::endl
+      << leafDataTypeToString(type);
+    if (std::holds_alternative<yang::Enum>(type)) {
+        s << "{";
+        auto values = std::get<yang::Enum>(type).m_allowedValues;
+        std::transform(values.begin(), values.end(), std::experimental::make_ostream_joiner(s, ", "), [](const auto& value) {
+            return value.m_value;
+        });
+        s << "}";
+    }
+    if (std::holds_alternative<yang::IdentityRef>(type)) {
+        s << "{";
+        auto values = std::get<yang::IdentityRef>(type).m_allowedValues;
+        std::transform(values.begin(), values.end(), std::experimental::make_ostream_joiner(s, ", "), [](const auto& value) {
+            std::string res;
+            if (value.m_prefix) {
+                res += value.m_prefix->m_name;
+                res += ":";
+            }
+            res += value.m_value;
+            return res;
+        });
+        s << "}";
+    }
+    s << std::endl;
+    return s;
+}
 }