added more tests

test/gaussscheSummenformel/test_gaussscheSummenformel.c

@@ -5,6 +5,10 @@ void setUP(){}
 void tearDown(){}
 
 void test_gaussscheSummenformel() {
+
 	TEST_ASSERT_EQUAL_INT(1, gaussscheSummenformel(1));
+	TEST_ASSERT_EQUAL_INT(15, gaussscheSummenformel(5));
+	TEST_ASSERT_EQUAL_INT(55, gaussscheSummenformel(10));
+	TEST_ASSERT_EQUAL_INT(5050, gaussscheSummenformel(100));
 
 }