TestCase.java

@Test
public void it_should_test_when_product_id_is_valid() throws Exception {
  //given
  ProductRequest productRequest = ProductRequest.builder().id(1).build();
  ArgumentCaptor<ProductRequest> argumentCaptor = ArgumentCaptor.forClass(ProductRequest.class);
  //when
  ResultActions result = mockMvc.perform(post("/products")
                  .content(objectMapper.writeValueAsString(productRequest))
                  .contentType(MediaType.APPLICATION_JSON));
  //then
  verify(productService).dispense(argumentCaptor.capture());
  result.andExpect(status().isOk());
}