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SpringMockK Documentation

repository·master·Indexed 19 days ago

https://github.com/ninja-squad/springmockk

SpringMockK provides support for Spring Boot integration tests written in Kotlin by using MockK instead of Mockito. It offers Kotlin-friendly alternatives to Spring's Mockito-based annotations, such as @MockkBean and @MockkSpyBean, to create mock and spy beans within the Spring ApplicationContext.

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What's inside SpringMockK

  1. Configure Qualifier annotations for @MockkBean

    master

    When using custom qualifier annotations with @MockkBean, ensure the annotation targets fields rather than properties. If your annotation targets properties, use the @field: site-target prefix to ensure it is applied correctly to the bean:

    @MockkBean
@field:YourQualifier
private lateinit var myService: MyService

  2. Stubbing beans wrapped in Spring AOP proxies

    master
    When spying on a bean that is wrapped in a Spring AOP proxy (e.g., due to @Cacheable), you cannot stub or verify the bean directly. You must target the underlying object. Use AopTestUtils.getUltimateTargetObject() to retrieve the actual target for stubbing and verification.

  3. Use @MockkBean and @MockkSpyBean for Spring integration tests

    master

    SpringMockK provides Kotlin-friendly alternatives to Spring's Mockito annotations. Use @MockkBean to create a mock bean and @MockkSpyBean to create a spy bean within the Spring ApplicationContext.

    Mocking Behavior

    By default, mocks created with these annotations are strict (not relaxed). You can configure them using:

    • @MockkBean(relaxed = true)
    • @MockkBean(relaxUnitFun = true)

    Example Usage

    @ExtendWith(SpringExtension::class)
@WebMvcTest
class GreetingControllerTest {
    @MockkBean
    private lateinit var greetingService: GreetingService
    
    @Autowired
    private lateinit var controller: GreetingController
    
    @Test
    fun `should greet by delegating to the greeting service`() {
        every { greetingService.greet("John") } returns "Hi John"
        
        assertThat(controller.greet("John")).isEqualTo("Hi John")
        verify { greetingService.greet("John") }
    }
}

  4. Migrate to SpringMockK 5.x

    master

    If upgrading from version 4.x or earlier to 5.x, apply the following changes to align with the Spring Framework's native Mockito support:

    • Rename Annotation: Replace @SpykBean with @MockkSpyBean.
    • Repeatable Annotations: @MockkBean and @MockkSpyBean are now natively repeatable in Kotlin. Do not use @MockkBeans or @SpykBeans; instead, repeat the individual annotations.
    • Rename classes to types: Change @MockkBean(classes = [SomeService::class]) to @MockkBean(types = [SomeService::class]).
    • Rename value to name: The value property is now an alias for name. If you were using @MockkBean([SomeService::class]), rewrite it as @MockkBean(types = [SomeService::class]).
    • Rename Extension Property: com.ninjasquad.springmockk.MockkFunctionsKt.isMock is now isMockOrSpy.

  5. Install SpringMockK via Gradle or Maven

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    To use SpringMockK in your Kotlin Spring Boot integration tests, add the dependency to your build configuration.

    Gradle (Kotlin DSL)

    Add the following to your dependencies block:

    Maven

    Add the following to your dependencies block:

    Note: Ensure you use the version compatible with your Spring/Java environment.

    // Gradle (Kotlin DSL)
testImplementation("com.ninja-squad:springmockk:5.0.1")

<!-- Maven -->
<dependency>
  <groupId>com.ninja-squad</groupId>
  <artifactId>springmockk</artifactId>
  <version>5.0.1</version>
  <scope>test</scope>
</dependency>```

  6. Handle JDK proxy issues when spying with MockK

    master

    In Java 16+, MockK may fail to spy on JDK proxies, resulting in an java.lang.IllegalAccessException. To resolve this, you must pass the --add-opens java.base/java.lang.reflect=ALL-UNNAMED argument to the JVM running your tests.

    Gradle Configuration

    tasks.test {
    jvmArgs(
        "--add-opens", "java.base/java.lang.reflect=ALL-UNNAMED"
    )
}

    Maven Configuration

    <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <configuration>
      <argLine>
        --add-opens java.base/java.lang.reflect=ALL-UNNAMED
      </argLine>
    </configuration>
</plugin>