Testing Pyramid Agent Skill

> Use when writing tests of any kind — unit, slice, or integration. Covers test structure, naming conventions, Mockito patterns, @WebMvcTest, @DataJpaTest, and Testcontainers setup.

2k tokens

context cost

the whole folder, loaded on every use

files

instructions only

copies elsewhere

how many repositories repackaged it

190

stars on the repo

on the repository, not the skill itself

Install

one command, takes just this skill from the repository

npx skills add https://github.com/rrezartprebreza/spring-boot-skills --skill testing-pyramid

The instruction itself

9 sections, as written by the author

Testing Pyramid

Structure

Unit Tests         — fast, no Spring context, mock dependencies    (70%)
Slice Tests        — partial Spring context (@WebMvcTest, @DataJpaTest) (20%)
Integration Tests  — full context + real DB via Testcontainers     (10%)

Unit Tests — Services

@ExtendWith(MockitoExtension.class)
class OrderServiceTest {

    @Mock private OrderRepository orderRepository;
    @Mock private InventoryService inventoryService;

    @InjectMocks private OrderService orderService;

    @Test
    void createOrder_whenItemsAvailable_shouldSaveAndReturnOrder() {
        // Given
        var request = new CreateOrderRequest("[email protected]", List.of(new OrderItemRequest(UUID.randomUUID(), 2)));
        var savedOrder = Order.create("[email protected]");
        when(orderRepository.save(any(Order.class))).thenReturn(savedOrder);
        doNothing().when(inventoryService).reserve(any());

        // When
        Order result = orderService.createOrder(request);

        // Then
        assertThat(result).isNotNull();
        assertThat(result.getCustomerEmail()).isEqualTo("[email protected]");
        verify(inventoryService).reserve(request.items());
        verify(orderRepository).save(any(Order.class));
    }

    @Test
    void createOrder_whenInventoryUnavailable_shouldThrowException() {
        // Given
        var request = new CreateOrderRequest("[email protected]", List.of());
        doThrow(new InsufficientInventoryException("Out of stock"))
            .when(inventoryService).reserve(any());

        // When / Then
        assertThatThrownBy(() -> orderService.createOrder(request))
            .isInstanceOf(InsufficientInventoryException.class)
            .hasMessage("Out of stock");
    }
}

Slice Tests — Controllers (@WebMvcTest)

@WebMvcTest(OrderController.class)
class OrderControllerTest {

    @Autowired MockMvc mockMvc;
    @Autowired ObjectMapper objectMapper;
    @MockitoBean OrderService orderService;

    @Test
    @WithMockUser(roles = "USER")
    void createOrder_withValidRequest_shouldReturn201() throws Exception {
        // Given
        var request = new CreateOrderRequest("[email protected]", List.of());
        var order = Order.create("[email protected]");
        when(orderService.createOrder(any())).thenReturn(order);

        // When / Then
        mockMvc.perform(post("/api/v1/orders")
                .contentType(MediaType.APPLICATION_JSON)
                .content(objectMapper.writeValueAsString(request)))
            .andExpect(status().isCreated())
            .andExpect(jsonPath("$.success").value(true))
            .andExpect(jsonPath("$.data.customerEmail").value("[email protected]"));
    }

    @Test
    @WithMockUser
    void createOrder_withInvalidRequest_shouldReturn400() throws Exception {
        mockMvc.perform(post("/api/v1/orders")
                .contentType(MediaType.APPLICATION_JSON)
                .content("{}")) // missing required fields
            .andExpect(status().isBadRequest())
            .andExpect(jsonPath("$.success").value(false))
            .andExpect(jsonPath("$.error.code").value("VALIDATION_FAILED"));
    }
}

Slice Tests — Repositories (@DataJpaTest)

@DataJpaTest
@AutoConfigureTestDatabase(replace = Replace.NONE) // use real DB (Testcontainers)
@Import(TestcontainersConfig.class)
class OrderRepositoryTest {

    @Autowired OrderRepository orderRepository;

    @Test
    void findByStatus_shouldReturnMatchingOrders() {
        // Given
        var order1 = orderRepository.save(Order.create("[email protected]"));
        var order2 = orderRepository.save(Order.create("[email protected]"));
        order2.ship(); // change status
        orderRepository.save(order2);

        // When
        List<Order> pending = orderRepository.findByStatus(OrderStatus.PENDING, Pageable.unpaged()).getContent();

        // Then
        assertThat(pending).hasSize(1);
        assertThat(pending.get(0).getCustomerEmail()).isEqualTo("[email protected]");
    }
}

Integration Tests — Testcontainers

// Shared config — reuse container across tests
@TestConfiguration(proxyBeanMethods = false)
public class TestcontainersConfig {

    @Bean
    @ServiceConnection
    PostgreSQLContainer<?> postgresContainer() {
        return new PostgreSQLContainer<>("postgres:16-alpine");
    }
}

// Full integration test
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
@AutoConfigureRestTestClient
@Import(TestcontainersConfig.class)
class OrderIntegrationTest {

    @Autowired RestTestClient restTestClient;
    @Autowired OrderRepository orderRepository;

    @Test
    void createAndRetrieveOrder_endToEnd() {
        // Create
        var createRequest = new CreateOrderRequest("[email protected]", List.of());
        restTestClient.post()
            .uri("/api/v1/orders")
            .body(createRequest)
            .exchange()
            .expectStatus().isCreated()
            .expectBody(ApiResponse.class);

        // Retrieve
        // ... assert persisted correctly
    }
}

Naming Convention

// Method name: methodName_condition_expectedBehavior
createOrder_whenItemsAvailable_shouldSaveOrder()
findById_whenOrderNotFound_shouldThrowNotFoundException()
login_withInvalidCredentials_shouldReturn401()

Testcontainers Dependencies

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-testcontainers</artifactId>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.testcontainers</groupId>
    <artifactId>postgresql</artifactId>
    <scope>test</scope>
</dependency>

Gotchas

Agent uses @SpringBootTest for everything — use slices for speed
Agent uses H2 in-memory DB for @DataJpaTest — use Testcontainers for accuracy
Agent uses @MockBean — removed in Boot 4; use @MockitoBean (and @MockitoSpyBean for spies)
Agent uses TestRestTemplate by habit — prefer RestTestClient with @AutoConfigureRestTestClient for Boot 4 HTTP integration tests
Agent uses Mockito.mock() instead of @Mock — use annotations with @ExtendWith(MockitoExtension.class)
Agent forgets @WithMockUser on controller tests — security filter blocks all requests
Agent uses assertEquals from JUnit — use AssertJ (assertThat(...).isEqualTo(...))
Agent names tests test_createOrder() — use createOrder_condition_expected() pattern

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How to use it

Copy the folder

Take rrezartprebreza/spring-boot-testing-pyramid from the repository into ~/.claude/skills for personal use, or into .claude/skills inside a project.

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