Spring Testing - Initializing ConfigurableApplicationContext with ApplicationContextInitializer.

ApplicationContextInitializer in general can be used for some programmatic initialization of the application context. For example, registering property sources or activating profiles with the context environment.

This example demonstrates how to use ApplicationContextInitializer with Spring tests by using 'initializers' element of @ContextConfiguration.

Example

Creating a simple Spring application

@Configuration
public class AppConfig {

  @Bean
  @Profile("windows")
  public MyService myServiceA() {
      return new MyServiceA();
  }

  @Bean
  @Profile("other")
  public MyService myServiceB() {
      return new MyServiceB();
  }
}

public interface MyService {
  public String doSomething();

}

public class MyServiceA implements MyService {

  @Override
  public String doSomething() {
      return "in " + this.getClass().getSimpleName();
  }
}

public class MyServiceB implements MyService {

  @Override
  public String doSomething() {
      return "in " + this.getClass().getSimpleName();
  }
}

Implementing the Initializer

public class MyApplicationContextInitializer implements
      ApplicationContextInitializer<ConfigurableApplicationContext> {

  @Override
  public void initialize(ConfigurableApplicationContext ac) {
      String os = System.getProperty("os.name");
      String profile = (os.toLowerCase().startsWith("windows")) ? "windows" : "other";
      ConfigurableEnvironment ce = ac.getEnvironment();
      ce.addActiveProfile(profile);
  }
}

The JUnit test

Following test will fail if run other than Windows O.S.

@RunWith(SpringRunner.class)
@ContextConfiguration(classes = AppConfig.class,
      initializers = MyApplicationContextInitializer.class)
public class MyServiceTests {

  @Autowired
  private MyService dataService;

  @Test
  public void testDoSomething() {
      String s = dataService.doSomething();
      System.out.println(s);
      Assert.assertEquals("in MyServiceA", s);
  }
}

mvn  -q test -Dtest=MyServiceTests

Output

d:\example-projects\spring-core-testing\application-context-initializer-in-test>mvn  -q test -Dtest=MyServiceTests

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.logicbig.example.MyServiceTests
in MyServiceA
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.409 sec

Results :

Tests run: 1, Failures: 0, Errors: 0, Skipped: 0

Example Project

Dependencies and Technologies Used:

• spring-context 4.3.8.RELEASE: Spring Context.
• spring-test 4.3.9.RELEASE: Spring TestContext Framework.
• junit 4.12: JUnit is a unit testing framework for Java, created by Erich Gamma and Kent Beck.
• JDK 1.8
• Maven 3.3.9