    @Test
    public void shouldReturnHelloSomkiat() {

        // Arrange
        Person somkiat = new Person("somkiat", "pui");
        given(personRepository.findByFirstName("somkiat"))
                .willReturn(Optional.of(somkiat));

        // Act
        Hello hello = controller.sayHi("somkiat");

        // Assert
        assertEquals("Hello somkiat", hello.getMessage());


    }