Override default Spring-Boot application.properties settings in Junit Test

Question

You can use @TestPropertySource to override values in application.properties. From its javadoc:

test property sources can be used to selectively override properties defined in system and application property sources

For example:

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = ExampleApplication.class)
@TestPropertySource(locations="classpath:test.properties")
public class ExampleApplicationTests {

}

Spring Boot automatically loads src/test/resources/application.properties, if following annotations are used

@RunWith(SpringRunner.class)
@SpringBootTest

So, rename test.properties to application.properties to utilize auto configuration.

If you only need to load the properties file (into the Environment) you can also use the following, as explained here

@RunWith(SpringRunner.class)
@ContextConfiguration(initializers = ConfigFileApplicationContextInitializer.class) 

[Update: Overriding certain properties for testing]

1. Add src/main/resources/application-test.properties.
2. Annotate test class with @ActiveProfiles("test").

This loads application.properties and then application-test.properties properties into application context for the test case, as per rules defined here.

Demo - https://github.com/mohnish82/so-spring-boot-testprops

You can also use meta-annotations to externalize the configuration. For example:

@RunWith(SpringJUnit4ClassRunner.class)
@DefaultTestAnnotations
public class ExampleApplicationTests { 
   ...
}

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@SpringApplicationConfiguration(classes = ExampleApplication.class)
@TestPropertySource(locations="classpath:test.properties")
public @interface DefaultTestAnnotations { }

Another approach suitable for overriding a few properties in your test, if you are using @SpringBootTest annotation:

@SpringBootTest(properties = {"propA=valueA", "propB=valueB"})

TLDR:

So what I did was to have the standard src/main/resources/application.properties and also a src/test/resources/application-default.properties where i override some settings for ALL my tests.

For power-developers:

In order to change/use even more easily different spring profiles, I have a now an application-default.yaml that declares the profiles I want to use. This file is not committed, so that each developer may choose his way of activating profiles and needs (e.g. feature) he/she is working on.

spring:
  profiles:
    include:
      - local
      - devlocal
      - wip
#      - kafka@docker

---
spring.profiles: wip
# ... overriding properties 

Whole Story

I ran into the same problem and was not using profiles either so far. It seemed to be bothersome to have to do it now and remember declaring the profile -- which can be easily forgotten.

The trick is, to leverage that a profile specific application-<profile>.properties overrides settings in the general profile. See https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-external-config.html#boot-features-external-config-profile-specific-properties.