Spring Boot properties in 'application.yml' not loading from JUnit Test

What am I doing wrong? I'm using this little standalone App which runs and finds my src/main/resources/config/application.yml. The same configuration doesn't work from JUnit, see below:

@Configuration
@ComponentScan
@EnableConfigurationProperties

public class TestApplication {

    public static void main(String[] args) {

        SpringApplication.run(TestApplication.class);
    }
}


@Component
@ConfigurationProperties

public class Bean{
    ...
}

The following doesn't work, the same properties in application.yml are not loaded and Bean has only null values:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = TestApplication.class)

public class SomeTestClass {
    ...
}

Try this:

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = TestApplication.class, 
    initializers = ConfigFileApplicationContextInitializer.class)
public class SomeTestClass {
    ...
}

EDIT:

For Spring Boot version 1.5+, SpringApplicationConfiguration was removed in favour of SpringBootTest or direct use of SpringBootContextLoader.

You can still use initializers parameter with ContextConfiguration annotation.

The trick to load any custom yml file in SpringBoot 2.0 w/o using @SpringBootTest

• create some yml file in test\resources
• Use ConfigFileApplicationContextInitializer and spring.config.location property

Example Code:

@RunWith(SpringRunner.class)
@ContextConfiguration(
    classes = { MyConfiguration.class, AnotherDependancy.class },
    initializers = {ConfigFileApplicationContextInitializer.class} )
@TestPropertySource(properties = { "spring.config.location=classpath:myApp-test.yml" })
public class ConfigProviderTest {
    @Autowired
    private MyConfiguration myConfiguration; //this will be filled with myApp-test.yml 

   @Value("${my.config-yml-string}")
   private String someSrting; //will get value from the yml file.

}

For JUnit 5 use the @ExtendWith(SpringExtension.class) annotation instead of @RunWith(SpringRunner.class)

Alternative in February 2017:

@SpringBootTest
@ContextConfiguration(classes = { TestApplication.class })
@RunWith(SpringRunner.class)
public class SomeTestClass {
   ...
}

the lean variant (withouth @SpringBootTest):

@ContextConfiguration(classes = { TestApplication.class },
                 initializers = { ConfigFileApplicationContextInitializer.class })
@RunWith(SpringRunner.class)
public class SomeTestClass {

Here's another way: [Spring Boot v1.4.x]

@Configuration
@ConfigurationProperties(prefix = "own")
public class OwnSettings {

    private String name;
    Getter & setters...

}

---

import org.springframework.boot.test.context.SpringBootTestContextBootstrapper;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@BootstrapWith(SpringBootTestContextBootstrapper.class)
public class OwnSettingsTest {

  @Autowired
  private OwnSettings bean;

  @Test
  public void test() {
    bean.getName();
  }
}

This works ONLY if also 'application.properties' file exists.

e.g. maven project:

src/main/resources/application.properties [ The file can be empty but it's mandatory! ]
src/main/resources/application.yml [here's your real config file]

Unit test with Spring Boot 2

spring boot 2 support 'application.properties' by default, for 'application.yml' just add below:

@TestPropertySource(properties = { "spring.config.location=classpath:application.yml" })

e.g.

@RunWith(SpringRunner.class)
@SpringBootTest
@TestPropertySource(properties = { "spring.config.location=classpath:application.yml" })
public class ServiceTest {...}

adding to Liam's answer, an alternative will be:

@TestPropertySource(locations = { "classpath:application.yaml" })

the key difference here is that the test will fail with a file not found exception if application.yaml is not in your /test/resources directory

Spring boot 2 example:

private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
        .withInitializer(new ConfigFileApplicationContextInitializer());

@Test public void test() throws Exception {
    
    this.contextRunner
    .withUserConfiguration(TestApplication.class)
    .run((context) -> {
        
        .....

    });
}

In my case I was trying to test a library without a @SpringBootApp declared in the regular app classpath, but I do have one in my test context. After debugging my way through the Spring Boot initialization process, I discovered that Spring Boot's YamlPropertySourceLoader (as of 1.5.2.RELEASE) will not load YAML properties unless org.yaml.snakeyaml.Yaml is on the classpath. The solution for me was to add snakeyaml as a test dependency in my POM:

	<dependency>
		<groupId>org.yaml</groupId>
		<artifactId>snakeyaml</artifactId>
		<version>1.19</version>
		<scope>test</scope>
	</dependency>

extending Liam's answer

you can add spring.config.additional-location=classpath:application-overrides.yaml property so config from default location will be merged with the additional config provided:

@RunWith(SpringRunner.class)
@SpringBootTest
@TestPropertySource(properties = {
  "spring.config.additional-location=classpath:testcases/test-case-properties.yaml",
})
public class SpecificTestCaseIntegrationTest {

Since spring-boot version 2.6.0 org.springframework.boot.test.context.ConfigFileApplicationContextInitializer is deprecated and instead is recommended to be used org.springframework.boot.test.context.ConfigDataApplicationContextInitializer.

In your tests you can use it as:

@ContextConfiguration(classes = {
  ...        
}, initializers = ConfigDataApplicationContextInitializer.class)
public class MyTestingClassIT

This works

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@SpringBootTest
public class ApplicationTest {

	@Test
	public void contextLoads() {
	}

}