spring-boot-starter-test SPRING BOOT ka SABSE COMPREHENSIVE testing starter hai — JUnit 5 (MODERN test FRAMEWORK), Mockito (mocking library), AssertJ (FLUENT, READABLE assertions), Hamcrest (matchers), JSONassert, aur Spring TEST utilities (MockMvc, @SpringBootTest) — SAB EK SAATH.

Ye starter TEST SCOPE (<scope>test</scope>) mein hota hai — MATLAB YE DEPENDENCIES SIRF TEST CODE COMPILE/RUN karте waqt AVAILABLE hoती hain, FINAL PRODUCTION JAR mein INCLUDED NAHI hoti, isliye APPLICATION ka SIZE CHHOTA rehta hai.

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

// Ek dependency se, SAB kuch available:
import org.junit.jupiter.api.Test;
import static org.assertj.core.api.Assertions.assertThat;
import static org.mockito.Mockito.when;

@Test
void shouldFindUser() {
    when(repository.findById(1L)).thenReturn(Optional.of(new User()));
    assertThat(service.getUser(1L)).isNotNull();   // AssertJ fluent syntax
}