diff --git a/login_server/src/cpp/JSONInterface/JsonCheckUsername.cpp b/login_server/src/cpp/JSONInterface/JsonCheckUsername.cpp
index cf19ae69d..f05f503ee 100644
--- a/login_server/src/cpp/JSONInterface/JsonCheckUsername.cpp
+++ b/login_server/src/cpp/JSONInterface/JsonCheckUsername.cpp
@@ -23,8 +23,7 @@ Poco::JSON::Object* JsonCheckUsername::handle(Poco::Dynamic::Var params)
 		auto group_alias_obj = paramJsonObject->get("group_alias");
 
 		try {
-			paramJsonObject->get("username").convert(username);
-
+			
 			if (!username_obj.isEmpty()) {
 				username_obj.convert(username);
 			}
@@ -38,7 +37,7 @@ Poco::JSON::Object* JsonCheckUsername::handle(Poco::Dynamic::Var params)
 
 		}
 		catch (Poco::Exception& ex) {
-			return stateError("username not found or invalid");
+			return stateError("Poco Exception", ex.displayText());
 		}
 		
 	}
diff --git a/login_server/src/cpp/test/JSONInterface/TestJsonCheckUsername.cpp b/login_server/src/cpp/test/JSONInterface/TestJsonCheckUsername.cpp
new file mode 100644
index 000000000..d399689ee
--- /dev/null
+++ b/login_server/src/cpp/test/JSONInterface/TestJsonCheckUsername.cpp
@@ -0,0 +1,123 @@
+#include "gtest/gtest.h"
+
+#include "JSONInterface/JsonCheckUsername.h"
+
+TEST(TestJsonCheckUsername, InvalidGroupAlias)
+{
+	JsonCheckUsername jsonCall;
+	Poco::JSON::Object::Ptr params = new Poco::JSON::Object;
+	params->set("group_alias", "robert");
+	auto result = jsonCall.handle(params);
+	auto msg = result->get("msg");
+	ASSERT_FALSE(msg.isEmpty());
+	ASSERT_TRUE(msg.isString());
+	ASSERT_EQ(msg.toString(), "unknown group");
+
+	delete result;
+}
+
+TEST(TestJsonCheckUsername, InvalidGroupId)
+{
+	JsonCheckUsername jsonCall;
+	Poco::JSON::Object::Ptr params = new Poco::JSON::Object;
+	params->set("group_id", "4");
+	auto result = jsonCall.handle(params);
+	auto msg = result->get("msg");
+	ASSERT_FALSE(msg.isEmpty());
+	ASSERT_TRUE(msg.isString());
+	ASSERT_EQ(msg.toString(), "unknown group");
+
+	delete result;
+}
+
+TEST(TestJsonCheckUsername, ValidGroupAlias)
+{
+	JsonCheckUsername jsonCall;
+	Poco::JSON::Object::Ptr params = new Poco::JSON::Object;
+	params->set("group_alias", "gdd1");
+	auto result = jsonCall.handle(params);
+	auto state = result->get("state");
+	ASSERT_FALSE(state.isEmpty());
+	ASSERT_TRUE(state.isString());
+	ASSERT_EQ(state.toString(), "success");
+
+	auto group_id = result->get("group_id");
+	ASSERT_FALSE(group_id.isEmpty());
+	ASSERT_TRUE(group_id.isInteger());
+	int group_id_int = 0;
+	group_id.convert(group_id_int);
+	ASSERT_EQ(group_id_int, 1);
+
+	delete result;
+}
+
+TEST(TestJsonCheckUsername, UsernameWithoutGroup)
+{
+	JsonCheckUsername jsonCall;
+	Poco::JSON::Object::Ptr params = new Poco::JSON::Object;
+	params->set("username", "maxi");
+	auto result = jsonCall.handle(params);
+
+	auto state = result->get("state");
+	ASSERT_FALSE(state.isEmpty());
+	ASSERT_TRUE(state.isString());
+	ASSERT_EQ(state.toString(), "error");
+
+	auto msg = result->get("msg");
+	ASSERT_FALSE(msg.isEmpty());
+	ASSERT_TRUE(msg.isString());
+	ASSERT_EQ(msg.toString(), "no group given");
+	
+
+	delete result;
+}
+
+TEST(TestJsonCheckUsername, ExistingUsername)
+{
+	JsonCheckUsername jsonCall;
+	Poco::JSON::Object::Ptr params = new Poco::JSON::Object;
+	params->set("username", "Erfinder");
+	params->set("group_id", 1);
+	auto result = jsonCall.handle(params);
+
+	auto state = result->get("state");
+	ASSERT_FALSE(state.isEmpty());
+	ASSERT_TRUE(state.isString());
+	ASSERT_EQ(state.toString(), "warning");
+
+	auto msg = result->get("msg");
+	ASSERT_FALSE(msg.isEmpty());
+	ASSERT_TRUE(msg.isString());
+	ASSERT_EQ(msg.toString(), "username already in use");
+}
+
+TEST(TestJsonCheckUsername, NewUsername)
+{
+	JsonCheckUsername jsonCall;
+	Poco::JSON::Object::Ptr params = new Poco::JSON::Object;
+	params->set("username", "Maxi");
+	params->set("group_id", 1);
+	auto result = jsonCall.handle(params);
+
+	auto state = result->get("state");
+	ASSERT_FALSE(state.isEmpty());
+	ASSERT_TRUE(state.isString());
+	ASSERT_EQ(state.toString(), "success");
+}
+
+TEST(TestJsonCheckUsername, UsernameExistInOtherGroup)
+{
+	JsonCheckUsername jsonCall;
+	Poco::JSON::Object::Ptr params = new Poco::JSON::Object;
+	params->set("username", "Erfinder");
+	params->set("group_id", 2);
+	auto result = jsonCall.handle(params);
+
+	auto state = result->get("state");
+	ASSERT_FALSE(state.isEmpty());
+	ASSERT_TRUE(state.isString());
+	ASSERT_EQ(state.toString(), "success");
+
+}
+
+