Package org.springframework.boot.test.system

Class OutputCaptureExtension

java.lang.Object
org.springframework.boot.test.system.OutputCaptureExtension
All Implemented Interfaces:
org.junit.jupiter.api.extension.AfterAllCallback, org.junit.jupiter.api.extension.AfterEachCallback, org.junit.jupiter.api.extension.BeforeAllCallback, org.junit.jupiter.api.extension.BeforeEachCallback, org.junit.jupiter.api.extension.Extension, org.junit.jupiter.api.extension.ParameterResolver, org.junit.jupiter.api.extension.TestInstantiationAwareExtension
public class OutputCaptureExtension extends Object implements org.junit.jupiter.api.extension.BeforeAllCallback, org.junit.jupiter.api.extension.AfterAllCallback, org.junit.jupiter.api.extension.BeforeEachCallback, org.junit.jupiter.api.extension.AfterEachCallback, org.junit.jupiter.api.extension.ParameterResolver
JUnit Jupiter @Extension to capture System.out and System.err. Can be registered for an entire test class or for an individual test method through @ExtendWith. This extension provides parameter resolution for a CapturedOutput instance which can be used to assert that the correct output was written.

To use with @ExtendWith, inject the CapturedOutput as an argument to your test class constructor, test method, or lifecycle methods: 

 @ExtendWith(OutputCaptureExtension.class)
 class MyTest {

     @Test
     void test(CapturedOutput output) {
         System.out.println("ok");
         assertThat(output).contains("ok");
         System.err.println("error");
     }

     @AfterEach
     void after(CapturedOutput output) {
         assertThat(output.getOut()).contains("ok");
         assertThat(output.getErr()).contains("error");
     }

 }

To ensure that their output can be captured, Java Util Logging (JUL) and Log4j2 require additional configuration.

To reliably capture output from Java Util Logging, reset its configuration after each test: 

 @AfterEach
 void reset() throws Exception {
     LogManager.getLogManager().readConfiguration();
 }

To reliably capture output from Log4j2, set the follow attribute of the console appender to true: 

 <Appenders>
     <Console name="Console" target="SYSTEM_OUT" follow="true">
         ...
     </Console>
  </Appenders>
Since:
2.2.0
Author:
Madhura Bhave, Phillip Webb, Andy Wilkinson, Sam Brannen
See Also:

  • Nested Class Summary

    Nested classes/interfaces inherited from interface org.junit.jupiter.api.extension.TestInstantiationAwareExtension

    org.junit.jupiter.api.extension.TestInstantiationAwareExtension.ExtensionContextScope

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    afterAll(org.junit.jupiter.api.extension.ExtensionContext context)
     
    void
    afterEach(org.junit.jupiter.api.extension.ExtensionContext context)
     
    void
    beforeAll(org.junit.jupiter.api.extension.ExtensionContext context)
     
    void
    beforeEach(org.junit.jupiter.api.extension.ExtensionContext context)
     
    Object
    resolveParameter(org.junit.jupiter.api.extension.ParameterContext parameterContext, org.junit.jupiter.api.extension.ExtensionContext extensionContext)
     
    boolean
    supportsParameter(org.junit.jupiter.api.extension.ParameterContext parameterContext, org.junit.jupiter.api.extension.ExtensionContext extensionContext)
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    Methods inherited from interface org.junit.jupiter.api.extension.TestInstantiationAwareExtension

    getTestInstantiationExtensionContextScope

  • Method Details

    • beforeAll

      public void beforeAll(org.junit.jupiter.api.extension.ExtensionContext context) throws Exception
      Specified by:
      beforeAll in interface org.junit.jupiter.api.extension.BeforeAllCallback
      Throws:
      Exception

    • afterAll

      public void afterAll(org.junit.jupiter.api.extension.ExtensionContext context) throws Exception
      Specified by:
      afterAll in interface org.junit.jupiter.api.extension.AfterAllCallback
      Throws:
      Exception

    • beforeEach

      public void beforeEach(org.junit.jupiter.api.extension.ExtensionContext context) throws Exception
      Specified by:
      beforeEach in interface org.junit.jupiter.api.extension.BeforeEachCallback
      Throws:
      Exception

    • afterEach

      public void afterEach(org.junit.jupiter.api.extension.ExtensionContext context) throws Exception
      Specified by:
      afterEach in interface org.junit.jupiter.api.extension.AfterEachCallback
      Throws:
      Exception

    • supportsParameter

      public boolean supportsParameter(org.junit.jupiter.api.extension.ParameterContext parameterContext, org.junit.jupiter.api.extension.ExtensionContext extensionContext) throws org.junit.jupiter.api.extension.ParameterResolutionException
      Specified by:
      supportsParameter in interface org.junit.jupiter.api.extension.ParameterResolver
      Throws:
      org.junit.jupiter.api.extension.ParameterResolutionException

    • resolveParameter

      public Object resolveParameter(org.junit.jupiter.api.extension.ParameterContext parameterContext, org.junit.jupiter.api.extension.ExtensionContext extensionContext)
      Specified by:
      resolveParameter in interface org.junit.jupiter.api.extension.ParameterResolver