Merge pull request #24 from brianronock/part1-chapter12-testing

Part 1 - Chapter 12. Testing Strategies

Author: brianronock

Part1_RESTful-API-SpringBoot/src/test/java/com/example/springrest/controllers/ProductControllerTest.java

@@ -0,0 +1,72 @@
+package com.example.springrest.controllers;
+
+import com.example.springrest.mappers.ProductMapperImpl;
+import com.example.springrest.models.Product;
+import com.example.springrest.services.ProductService;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
+import org.springframework.boot.test.mock.mockito.MockBean;
+import org.springframework.context.annotation.Import;
+import org.springframework.test.web.servlet.MockMvc;
+
+import java.math.BigDecimal;
+
+import static org.mockito.Mockito.when;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+/**
+ * Unit tests for {@link ProductController} using Spring's {@link WebMvcTest} support.
+ *
+ * <p><strong>Test strategy:</strong>
+ * <ul>
+ *   <li>Start only the web layer (no database or services).</li>
+ *   <li>Inject a {@link MockMvc} client to simulate HTTP calls.</li>
+ *   <li>Replace the real {@link ProductService} with a Mockito mock using {@link MockBean}.</li>
+ *   <li>Import the {@link ProductMapperImpl} so that real mapping logic is used in tests.</li>
+ * </ul>
+ *
+ * <p><strong>Note on @MockBean:</strong>
+ * In Spring Boot 3.5+, {@link MockBean} is marked <em>deprecated</em>.
+ * It still works, but the Spring team is encouraging a shift toward
+ * alternative mocking approaches (e.g., plain Mockito with manual injection,
+ * or newer testing features like {@code @ServiceTest} in future releases).
+ * For the purposes of this book (Part 1), we continue to use {@link MockBean}
+ * for its simplicity. We will revisit alternatives in Part 3 when covering
+ * advanced testing strategies.
+ *
+ * <p><strong>Covered cases:</strong>
+ * <ul>
+ *   <li>{@link #getByIdReturnsProduct()} — verifies that GET by ID returns the expected JSON.</li>
+ *   <li>{@link #createValidationFail()} — verifies that invalid input is rejected with 400 and error details.</li>
+ * </ul>
+ */
+@WebMvcTest(ProductController.class)
+@Import(ProductMapperImpl.class)
+public class ProductControllerTest {
+    @Autowired private MockMvc mvc;
+    @MockBean private ProductService service;
+
+    @Test
+    void getByIdReturnsProduct() throws Exception {
+        Product prod = new Product("X", BigDecimal.ONE);
+        prod.setId(100L);
+        when(service.getOrThrow(100L)).thenReturn(prod);
+        mvc.perform(get("/api/products/100"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.id").value(100))
+                .andExpect(jsonPath("$.name").value("X"));
+    }
+
+    @Test
+    void createValidationFail() throws Exception {
+        String json = "{\"name\": \"\", \"price\": 0}";
+        mvc.perform(post("/api/products").contentType("application/json").content(json))
+                .andExpect(status().isBadRequest())
+                .andExpect(jsonPath("$.name").exists())
+                .andExpect(jsonPath("$.price").exists());
+    }
+}

Part1_RESTful-API-SpringBoot/src/test/java/com/example/springrest/repositories/ProductRepoTest.java

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+package com.example.springrest.repositories;
+
+import com.example.springrest.models.Product;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageRequest;
+
+import java.math.BigDecimal;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * Integration tests for {@link ProductRepo}.
+ *
+ * <p><strong>Responsibilities tested</strong>:
+ * <ul>
+ *   <li>Verifies that case-insensitive search works as expected using
+ *       {@code findByNameContainingIgnoreCase}.</li>
+ *   <li>Ensures substring search returns matching results.</li>
+ * </ul>
+ *
+ * <p><strong>Testing strategy</strong>:
+ * <ul>
+ *   <li>Uses Spring Boot’s {@link DataJpaTest}
+ *       annotation to bootstrap only JPA components with an in-memory H2 database.</li>
+ *   <li>Persists test data into the repository, then queries it with different search inputs.</li>
+ *   <li>Asserts that results match expectations regardless of case or partial strings.</li>
+ * </ul>
+ *
+ * <p>By default, tests are transactional and rolled back after each method,
+ * keeping the database clean between tests.</p>
+ */
+@DataJpaTest
+class ProductRepoTest {
+
+    @Autowired
+    ProductRepo repo;
+
+    @Test
+    void searchByNameIgnoreCase() {
+        repo.save(new Product("TestProduct", BigDecimal.TEN));
+        repo.save(new Product("Another", BigDecimal.ONE));
+
+        Page<Product> page = repo.findByNameContainingIgnoreCase("testproduct", PageRequest.of(0, 10));
+        assertEquals(1, page.getTotalElements());
+        Product result = page.getContent().get(0);
+        assertEquals("TestProduct", result.getName());
+
+        Page<Product> page2 = repo.findByNameContainingIgnoreCase("tes", PageRequest.of(0, 10));
+        assertEquals(1, page2.getTotalElements());
+    }
+
+
+}

Part1_RESTful-API-SpringBoot/src/test/java/com/example/springrest/services/ProductServiceTest.java

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+package com.example.springrest.services;
+
+import com.example.springrest.exceptions.ResourceNotFoundException;
+import com.example.springrest.models.Product;
+import com.example.springrest.repositories.ProductRepo;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import java.math.BigDecimal;
+import java.util.Optional;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+/**
+ * Unit tests for {@link ProductService}.
+ *
+ * <p><strong>Responsibilities tested</strong>:
+ * <ul>
+ *   <li>Ensures that {@code getOrThrow} correctly raises a
+ *       {@link ResourceNotFoundException}
+ *       when a product is not found in the repository.</li>
+ *   <li>Verifies that {@code update} applies field changes
+ *       (e.g., updating a product’s price) and persists them via the repository.</li>
+ * </ul>
+ *
+ * <p><strong>Testing strategy</strong>:
+ * <ul>
+ *   <li>Uses Mockito to mock {@link ProductRepo}
+ *       and inject it into the service under test.</li>
+ *   <li>Focuses purely on service logic, isolated from database or web concerns.</li>
+ *   <li>Asserts both behavior (exceptions thrown) and state changes
+ *       (updated price, repository interactions).</li>
+ * </ul>
+ */
+@ExtendWith(MockitoExtension.class)
+public class ProductServiceTest {
+
+    @Mock
+    ProductRepo repo;
+    @InjectMocks
+    ProductService service;
+
+    @Test
+    void getOrThrowsIfNotFound() {
+        when(repo.findById(42L)).thenReturn(Optional.empty());
+        assertThrows(ResourceNotFoundException.class, () -> service.getOrThrow(42L));
+    }
+
+    @Test
+    void updateChangesFields() {
+        Product existing = new Product("Old", BigDecimal.valueOf(5));
+        existing.setId(1L);
+        when(repo.findById(1L)).thenReturn(Optional.of(existing));
+        when(repo.save(existing)).thenReturn(existing);
+        service.update(1L, p -> p.setPrice(BigDecimal.TEN));
+        assertEquals(BigDecimal.TEN, existing.getPrice());
+        verify(repo).save(existing);
+    }
+}