+ * Copyright (C) 2019 Isira Seneviratne

-    static const char expected[12] = "Hello World!";
+    static const char expected[12] = {
'H','e','l','l','o','W','o','r','l','d','!','\0' };

All you had to do was remove the number 12 and let the compiler
determine the size of the array automatically. And you really
shouldn't add your name at the top of the file unless you wrote a
substantial chunk of the file.

-Alex