diff --git a/tests/data_query.cpp b/tests/data_query.cpp
index 5bc3222..5adc661 100644
--- a/tests/data_query.cpp
+++ b/tests/data_query.cpp
@@ -17,26 +17,10 @@
 #error "Unknown backend"
 #endif
 #include "data_query.hpp"
+#include "pretty_printers.hpp"
 #include "sysrepo_subscription.hpp"
 #include "utils.hpp"
 
-namespace std {
-std::ostream& operator<<(std::ostream& s, const std::vector<ListInstance> set)
-{
-    s << std::endl << "{" << std::endl;
-    std::transform(set.begin(), set.end(), std::experimental::make_ostream_joiner(s, ", \n"), [](const auto& map) {
-        std::ostringstream ss;
-        ss << "    {" << std::endl << "        ";
-        std::transform(map.begin(), map.end(), std::experimental::make_ostream_joiner(ss, ", \n        "), [](const auto& keyValue){
-            return "{" + keyValue.first + "{" + boost::core::demangle(keyValue.second.type().name()) + "}" + ", " + leafDataToString(keyValue.second) + "}";
-        });
-        ss << std::endl << "    }";
-        return ss.str();
-    });
-    s << std::endl << "}" << std::endl;
-    return s;
-}
-}
 
 TEST_CASE("data query")
 {
diff --git a/tests/keyvalue_completion.cpp b/tests/keyvalue_completion.cpp
index 61e90cd..b725dff2 100644
--- a/tests/keyvalue_completion.cpp
+++ b/tests/keyvalue_completion.cpp
@@ -11,17 +11,9 @@
 #include "ast_commands.hpp"
 #include "datastoreaccess_mock.hpp"
 #include "parser.hpp"
+#include "pretty_printers.hpp"
 #include "static_schema.hpp"
 
-namespace std {
-std::ostream& operator<<(std::ostream& s, const std::set<std::string> set)
-{
-    s << std::endl << "{";
-    std::copy(set.begin(), set.end(), std::experimental::make_ostream_joiner(s, ", "));
-    s << "}" << std::endl;
-    return s;
-}
-}
 
 TEST_CASE("keyvalue_completion")
 {
diff --git a/tests/leaf_editing.cpp b/tests/leaf_editing.cpp
index ca5c8d6..76e26d3 100644
--- a/tests/leaf_editing.cpp
+++ b/tests/leaf_editing.cpp
@@ -11,14 +11,10 @@
 #include "ast_commands.hpp"
 #include "leaf_data_helpers.hpp"
 #include "parser.hpp"
+#include "pretty_printers.hpp"
 #include "static_schema.hpp"
 #include "utils.hpp"
 
-std::ostream& operator<<(std::ostream& s, const set_ cmd)
-{
-    return s << "Command SET {path: " << pathToSchemaString(cmd.m_path, Prefixes::Always) << ", type " << boost::core::demangle(cmd.m_data.type().name()) << ", data: " << leafDataToString(cmd.m_data) << "}";
-}
-
 TEST_CASE("leaf editing")
 {
     auto schema = std::make_shared<StaticSchema>();
diff --git a/tests/pretty_printers.hpp b/tests/pretty_printers.hpp
index 69c06f5..5b747a1 100644
--- a/tests/pretty_printers.hpp
+++ b/tests/pretty_printers.hpp
@@ -6,6 +6,7 @@
 */
 
 #include <experimental/iterator>
+#include <sstream>
 #include "parser.hpp"
 #include "utils.hpp"
 namespace std {
@@ -107,6 +108,29 @@
     return s;
 }
 
+std::ostream& operator<<(std::ostream& s, const std::set<std::string> set)
+{
+    s << std::endl << "{";
+    std::copy(set.begin(), set.end(), std::experimental::make_ostream_joiner(s, ", "));
+    s << "}" << std::endl;
+    return s;
+}
+
+std::ostream& operator<<(std::ostream& s, const std::vector<ListInstance> set)
+{
+    s << std::endl << "{" << std::endl;
+    std::transform(set.begin(), set.end(), std::experimental::make_ostream_joiner(s, ", \n"), [](const auto& map) {
+        std::ostringstream ss;
+        ss << "    {" << std::endl << "        ";
+        std::transform(map.begin(), map.end(), std::experimental::make_ostream_joiner(ss, ", \n        "), [](const auto& keyValue){
+            return "{" + keyValue.first + "{" + boost::core::demangle(keyValue.second.type().name()) + "}" + ", " + leafDataToString(keyValue.second) + "}";
+        });
+        ss << std::endl << "    }";
+        return ss.str();
+    });
+    s << std::endl << "}" << std::endl;
+    return s;
+}
 }
 
 std::ostream& operator<<(std::ostream& s, const boost::variant<dataPath_, schemaPath_, module_>& path)
@@ -170,3 +194,8 @@
     s << "\n}\n";
     return s;
 }
+
+std::ostream& operator<<(std::ostream& s, const set_ cmd)
+{
+    return s << "Command SET {path: " << pathToSchemaString(cmd.m_path, Prefixes::Always) << ", type " << boost::core::demangle(cmd.m_data.type().name()) << ", data: " << leafDataToString(cmd.m_data) << "}";
+}
diff --git a/tests/yang.cpp b/tests/yang.cpp
index dd7a031..f50d76e 100644
--- a/tests/yang.cpp
+++ b/tests/yang.cpp
@@ -424,16 +424,6 @@
     }
 })";
 
-namespace std {
-std::ostream& operator<<(std::ostream& s, const std::set<std::string> set)
-{
-    s << std::endl << "{";
-    std::copy(set.begin(), set.end(), std::experimental::make_ostream_joiner(s, ", "));
-    s << "}" << std::endl;
-    return s;
-}
-}
-
 TEST_CASE("yangschema")
 {
     using namespace std::string_literals;