Springboot Tdd

Patterns:

• Arrange-Act-Assert
• Avoid partial mocks; prefer explicit stubbing
• Use @ParameterizedTest for variants

Web Layer Tests (MockMvc)

@WebMvcTest(MarketController.class)
class MarketControllerTest {
  @Autowired MockMvc mockMvc;
  @MockBean MarketService marketService;

  @Test
  void returnsMarkets() throws Exception {
    when(marketService.list(any())).thenReturn(Page.empty());

    mockMvc.perform(get("/api/markets"))
        .andExpect(status().isOk())
        .andExpect(jsonPath("$.content").isArray());
  }
}

Integration Tests (SpringBootTest)

@SpringBootTest
@AutoConfigureMockMvc
@ActiveProfiles("test")
class MarketIntegrationTest {
  @Autowired MockMvc mockMvc;

  @Test
  void createsMarket() throws Exception {
    mockMvc.perform(post("/api/markets")
        .contentType(MediaType.APPLICATION_JSON)
        .content("""
          {"name":"Test","description":"Desc","endDate":"2030-01-01T00:00:00Z","categories":["general"]}
        """))
      .andExpect(status().isCreated());
  }
}

Persistence Tests (DataJpaTest)

@DataJpaTest
@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
@Import(TestContainersConfig.class)
class MarketRepositoryTest {
  @Autowired MarketRepository repo;

  @Test
  void savesAndFinds() {
    MarketEntity entity = new MarketEntity();
    entity.setName("Test");
    repo.save(entity);

    Optional<MarketEntity> found = repo.findByName("Test");
    assertThat(found).isPresent();
  }
}

Testcontainers

• Use reusable containers for Postgres/Redis to mirror production
• Wire via @DynamicPropertySource to inject JDBC URLs into Spring context

Coverage (JaCoCo)

Maven snippet (use the latest version from Maven Central, or let spring-boot-dependencies BOM manage it):

<plugin>
  <groupId>org.jacoco</groupId>
  <artifactId>jacoco-maven-plugin</artifactId>
  <!-- version managed by Spring Boot BOM or set explicitly, e.g. 0.8.12 -->
  <executions>
    <execution>
      <goals><goal>prepare-agent</goal></goals>
    </execution>
    <execution>
      <id>report</id>
      <phase>verify</phase>
      <goals><goal>report</goal></goals>
    </execution>
  </executions>
</plugin>

Assertions

• Prefer AssertJ (assertThat) for readability
• For JSON responses, use jsonPath
• For exceptions: assertThatThrownBy(...)

Test Data Builders

class MarketBuilder {
  private String name = "Test";
  MarketBuilder withName(String name) { this.name = name; return this; }
  Market build() { return new Market(null, name, MarketStatus.ACTIVE); }
}

CI Commands

• Maven: mvn -T 4 test or mvn verify
• Gradle: ./gradlew test jacocoTestReport

Remember: Keep tests fast, isolated, and deterministic. Test behavior, not implementation details.