Capítulo 5: Tests REST API

Introducción

Su API REST debe responder correctamente a las solicitudes HTTP. MockMvc permite probar sus endpoints sin iniciar un servidor web real.

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🎯 Objetivos del Capítulo

Al final de este capítulo, usted sabrá:

1. ✅ Utilizar MockMvc para probar los endpoints
2. ✅ Probar GET, POST, PUT, DELETE
3. ✅ Validar las respuestas JSON
4. ✅ Probar errores y excepciones
5. ✅ Probar con autenticación

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1. Configuración de MockMvc

Con @WebMvcTest

@WebMvcTest(ProductController.class)
class ProductControllerTest {

    @Autowired
    private MockMvc mockMvc;

    @MockBean
    private ProductService productService;

    @Test
    void shouldReturnProducts() throws Exception {
        mockMvc.perform(get("/api/products"))
            .andExpect(status().isOk());
    }
}

Con @SpringBootTest

@SpringBootTest
@AutoConfigureMockMvc  // ← Configura MockMvc
class FullIntegrationTest {

    @Autowired
    private MockMvc mockMvc;

    @Test
    void testWithRealServices() throws Exception {
        mockMvc.perform(get("/api/products"))
            .andExpect(status().isOk());
    }
}

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2. Test GET

GET Simple

@Test
void shouldReturnAllProducts() throws Exception {
    when(productService.findAll()).thenReturn(List.of(
        new Product(1L, "Laptop", 1000.0),
        new Product(2L, "Phone", 500.0)
    ));

    mockMvc.perform(get("/api/products"))
        .andExpect(status().isOk())
        .andExpect(content().contentType(MediaType.APPLICATION_JSON))
        .andExpect(jsonPath("$").isArray())
        .andExpect(jsonPath("$.length()").value(2))
        .andExpect(jsonPath("$[0].name").value("Laptop"))
        .andExpect(jsonPath("$[1].price").value(500.0));
}

GET con Path Variable

@Test
void shouldReturnProductById() throws Exception {
    when(productService.findById(1L))
        .thenReturn(Optional.of(new Product(1L, "Laptop", 1000.0)));

    mockMvc.perform(get("/api/products/{id}", 1))
        .andExpect(status().isOk())
        .andExpect(jsonPath("$.id").value(1))
        .andExpect(jsonPath("$.name").value("Laptop"));
}

GET con Query Parameters

@Test
void shouldSearchProducts() throws Exception {
    when(productService.search("laptop", 500.0, 1500.0))
        .thenReturn(List.of(new Product(1L, "Laptop", 1000.0)));

    mockMvc.perform(get("/api/products/search")
            .param("query", "laptop")
            .param("minPrice", "500")
            .param("maxPrice", "1500"))
        .andExpect(status().isOk())
        .andExpect(jsonPath("$.length()").value(1));
}

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3. Test POST

POST con JSON Body

@Test
void shouldCreateProduct() throws Exception {
    Product newProduct = new Product(null, "Tablet", 600.0);
    Product savedProduct = new Product(1L, "Tablet", 600.0);
    
    when(productService.save(any(Product.class))).thenReturn(savedProduct);

    mockMvc.perform(post("/api/products")
            .contentType(MediaType.APPLICATION_JSON)
            .content("""
                {
                    "name": "Tablet",
                    "price": 600.0
                }
                """))
        .andExpect(status().isCreated())
        .andExpect(jsonPath("$.id").value(1))
        .andExpect(jsonPath("$.name").value("Tablet"));
}

Con ObjectMapper

@Autowired
private ObjectMapper objectMapper;

@Test
void shouldCreateProductWithObjectMapper() throws Exception {
    Product product = new Product(null, "Tablet", 600.0);
    
    when(productService.save(any())).thenReturn(new Product(1L, "Tablet", 600.0));

    mockMvc.perform(post("/api/products")
            .contentType(MediaType.APPLICATION_JSON)
            .content(objectMapper.writeValueAsString(product)))
        .andExpect(status().isCreated());
}

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4. Test PUT

@Test
void shouldUpdateProduct() throws Exception {
    Product updated = new Product(1L, "Updated Laptop", 1200.0);
    
    when(productService.update(eq(1L), any())).thenReturn(updated);

    mockMvc.perform(put("/api/products/{id}", 1)
            .contentType(MediaType.APPLICATION_JSON)
            .content("""
                {
                    "name": "Updated Laptop",
                    "price": 1200.0
                }
                """))
        .andExpect(status().isOk())
        .andExpect(jsonPath("$.name").value("Updated Laptop"))
        .andExpect(jsonPath("$.price").value(1200.0));
}

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5. Test DELETE

@Test
void shouldDeleteProduct() throws Exception {
    doNothing().when(productService).delete(1L);

    mockMvc.perform(delete("/api/products/{id}", 1))
        .andExpect(status().isNoContent());
    
    verify(productService).delete(1L);
}

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6. Probar Errores

404 Not Found

@Test
void shouldReturn404WhenProductNotFound() throws Exception {
    when(productService.findById(999L))
        .thenThrow(new ProductNotFoundException(999L));

    mockMvc.perform(get("/api/products/{id}", 999))
        .andExpect(status().isNotFound())
        .andExpect(jsonPath("$.message").value("Product not found: 999"));
}

400 Bad Request (Validación)

@Test
void shouldReturn400WhenValidationFails() throws Exception {
    mockMvc.perform(post("/api/products")
            .contentType(MediaType.APPLICATION_JSON)
            .content("""
                {
                    "name": "",
                    "price": -100
                }
                """))
        .andExpect(status().isBadRequest())
        .andExpect(jsonPath("$.errors").isArray())
        .andExpect(jsonPath("$.errors[*].field").value(hasItem("name")));
}

500 Internal Server Error

@Test
void shouldReturn500OnServerError() throws Exception {
    when(productService.findAll())
        .thenThrow(new RuntimeException("Database connection failed"));

    mockMvc.perform(get("/api/products"))
        .andExpect(status().isInternalServerError());
}

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7. Expresiones JSONPath

Sintaxis Común

// Valor simple
jsonPath("$.name").value("Laptop")

// Elemento de arreglo
jsonPath("$[0].name").value("First")
jsonPath("$[1].price").value(100.0)

// Tamaño del arreglo
jsonPath("$.length()").value(5)
jsonPath("$").isArray()

// Existencia
jsonPath("$.id").exists()
jsonPath("$.deleted").doesNotExist()

// Tipo
jsonPath("$.price").isNumber()
jsonPath("$.name").isString()
jsonPath("$.items").isArray()

// Comparación
jsonPath("$.price").value(greaterThan(100.0)))
jsonPath("$.items.length()").value(lessThanOrEqualTo(10)))

// Wildcard
jsonPath("$[*].name").value(hasItem("Laptop"))
jsonPath("$.items[*].price").value(everyItem(greaterThan(0.0))))

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8. Test con Autenticación

Sin Security (Mock)

@WebMvcTest(ProductController.class)
@AutoConfigureMockMvc(addFilters = false)  // ← Desactiva los filtros de Security
class ProductControllerNoSecurityTest {
    // Tests sin autenticación
}

Con @WithMockUser

@WebMvcTest(ProductController.class)
class SecuredControllerTest {

    @Autowired
    private MockMvc mockMvc;

    @Test
    @WithMockUser(username = "admin", roles = {"ADMIN"})
    void adminCanAccessAdminEndpoint() throws Exception {
        mockMvc.perform(get("/api/admin/products"))
            .andExpect(status().isOk());
    }

    @Test
    @WithMockUser(username = "user", roles = {"USER"})
    void userCannotAccessAdminEndpoint() throws Exception {
        mockMvc.perform(get("/api/admin/products"))
            .andExpect(status().isForbidden());
    }

    @Test
    void anonymousCannotAccess() throws Exception {
        mockMvc.perform(get("/api/products"))
            .andExpect(status().isUnauthorized());
    }
}

Con JWT

@Test
void shouldAccessWithValidToken() throws Exception {
    String token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...";

    mockMvc.perform(get("/api/products")
            .header("Authorization", "Bearer " + token))
        .andExpect(status().isOk());
}

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9. Debug y Logging

andDo(print())

@Test
void debugTest() throws Exception {
    mockMvc.perform(get("/api/products"))
        .andDo(print())  // ← Muestra la solicitud y respuesta completas
        .andExpect(status().isOk());
}

Salida de Ejemplo

MockHttpServletRequest:
      HTTP Method = GET
      Request URI = /api/products
      Parameters = {}
      Headers = []

MockHttpServletResponse:
           Status = 200
    Content type = application/json
           Body = [{"id":1,"name":"Laptop","price":1000.0}]

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10. Ejemplo Completo CRUD

@WebMvcTest(ProductController.class)
class ProductControllerTest {

    @Autowired
    private MockMvc mockMvc;
    
    @Autowired
    private ObjectMapper objectMapper;

    @MockBean
    private ProductService productService;

    // CREATE
    @Test
    void shouldCreateProduct() throws Exception {
        when(productService.save(any())).thenReturn(new Product(1L, "Laptop", 1000.0));

        mockMvc.perform(post("/api/products")
                .contentType(MediaType.APPLICATION_JSON)
                .content("{\"name\":\"Laptop\",\"price\":1000.0}"))
            .andExpect(status().isCreated())
            .andExpect(header().exists("Location"))
            .andExpect(jsonPath("$.id").value(1));
    }

    // READ ALL
    @Test
    void shouldReturnAllProducts() throws Exception {
        when(productService.findAll()).thenReturn(List.of(
            new Product(1L, "Laptop", 1000.0),
            new Product(2L, "Phone", 500.0)
        ));

        mockMvc.perform(get("/api/products"))
            .andExpect(status().isOk())
            .andExpect(jsonPath("$.length()").value(2));
    }

    // READ ONE
    @Test
    void shouldReturnProductById() throws Exception {
        when(productService.findById(1L))
            .thenReturn(Optional.of(new Product(1L, "Laptop", 1000.0)));

        mockMvc.perform(get("/api/products/1"))
            .andExpect(status().isOk())
            .andExpect(jsonPath("$.name").value("Laptop"));
    }

    // UPDATE
    @Test
    void shouldUpdateProduct() throws Exception {
        when(productService.update(eq(1L), any()))
            .thenReturn(new Product(1L, "Updated", 1500.0));

        mockMvc.perform(put("/api/products/1")
                .contentType(MediaType.APPLICATION_JSON)
                .content("{\"name\":\"Updated\",\"price\":1500.0}"))
            .andExpect(status().isOk())
            .andExpect(jsonPath("$.name").value("Updated"));
    }

    // DELETE
    @Test
    void shouldDeleteProduct() throws Exception {
        mockMvc.perform(delete("/api/products/1"))
            .andExpect(status().isNoContent());
        
        verify(productService).delete(1L);
    }

    // ERROR - Not Found
    @Test
    void shouldReturn404() throws Exception {
        when(productService.findById(999L)).thenReturn(Optional.empty());

        mockMvc.perform(get("/api/products/999"))
            .andExpect(status().isNotFound());
    }

    // ERROR - Validation
    @Test
    void shouldReturn400OnInvalidData() throws Exception {
        mockMvc.perform(post("/api/products")
                .contentType(MediaType.APPLICATION_JSON)
                .content("{\"name\":\"\",\"price\":-1}"))
            .andExpect(status().isBadRequest());
    }
}

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11. Resumen

Métodos MockMvc

Método	Uso
get()	Solicitud GET
post()	Solicitud POST
put()	Solicitud PUT
delete()	Solicitud DELETE
patch()	Solicitud PATCH

Aserciones Comunes

.andExpect(status().isOk())              // 200
.andExpect(status().isCreated())         // 201
.andExpect(status().isNoContent())       // 204
.andExpect(status().isBadRequest())      // 400
.andExpect(status().isUnauthorized())    // 401
.andExpect(status().isForbidden())       // 403
.andExpect(status().isNotFound())        // 404
.andExpect(status().isInternalServerError()) // 500

.andExpect(content().contentType(MediaType.APPLICATION_JSON))
.andExpect(jsonPath("$.field").value(expected))
.andExpect(header().exists("Location"))

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🎯 Próximo Paso

¡Hora de la práctica! Los TPs le permitirán dominar las pruebas.

➡️ TP9.1: Tests Unitarios - Service Layer

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⬅️ Volver al Módulo 9