Notes on API Testing and Assertions

Overview of the Lecture

• Focus on enhancing test assertions for API endpoints.
• Importance of thorough testing beyond just checking creation.

Key Points on Assertions

• Current assertions are considered insufficient.
• Need to validate the actual response from the API endpoint.
• Use of mock MVC result handlers for testing.

Steps to Enhance Assertions

1. Capture API Response

   • Utilize mock MVC result handlers to see what is returned from the API.
   • Example: print method can be used temporarily to check response body.
   • Expected response attributes: name and type of returned data.

2. Implement Expect Statements

   • Use mockMvcResultMatchers.jsonPath to assert values in the response.
   • Example: expect(mockMvcResultMatchers.jsonPath("$.name").value(pokemonDto.getName()))
   • Validate that the attributes name and type match expected values.

3. Testing the Whole Response

   • Create a test method for fetching all Pokemon.
   • Mock service method to return a response DTO.
   • Example of setup: when(pokemonService.getAllPokemon(pageSize, pageNumber)).thenReturn(responseDto);

Building the Test Method

• Define the test method with proper annotations.
• Use a builder pattern to create response DTOs.
• Example: PokemonResponseDTO response = PokemonResponseDTO.builder().pageSize(10).last(true).pageNumber(1).content(new ArrayList<>(pokemonDtos)).build();

Performing the API Call

• Use mockMvc.perform(get(...)) to simulate the GET request.
• Set request parameters (pageNumber and pageSize) and content type.
  • Ensure content type is set to application/json.

Validating the Response

• Expect response status to be OK.
• Key focus on the content size of the response DTO.
• Use JSON path helpers to verify content size.

Error Handling

• Ensure proper constructors are added to models to avoid errors during tests.
• Utilize no-args constructors as necessary.

Conclusion

• Importance of comprehensive testing for API responses.
• Encouragement to engage with content by liking and subscribing.