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

I have a Spring-Boot application where the default properties are set in an application.properties file in the classpath (src/main/resources/application.properties).

I would like to override some default settings in my JUnit test with properties declared in a test.properties file (src/test/resources/test.properties)

I usualy have a dedicated Config Class for my Junit Tests, e.g.

package foo.bar.test;

import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;

@Configuration
@Import(CoreConfig.class)
@EnableAutoConfiguration
public class TestConfig {

}

I first thought that using @PropertySource("classpath:test.properties") in the TestConfig class would do the trick, but these properties will not overwrite the application.properties settings (see Spring-Boot Reference Doc - 23. Externalized Configuration).

Then I tried to use -Dspring.config.location=classpath:test.properties when invoking the test. That was successful - but I don't want to set this system property for each test execution. Thus I put it in the code

@Configuration
@Import(CoreConfig.class)
@EnableAutoConfiguration
public class TestConfig {

  static {
    System.setProperty("spring.config.location", "classpath:test.properties");
  }

}

which unfortunatly was again not successful.

There must be a simple solution on how to override application.properties settings in JUnit tests with test.properties that I must have overlooked.

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 { }

You can also create a application.properties file in src/test/resources where your JUnits are written.

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

Simple explanation:

If you are like me and you have the same application.properties in src/main/resources and src/test/resources, and you are wondering why the application.properties in your test folder is not overriding the application.properties in your main resources, read on...

If you have application.properties under src/main/resources and the same application.properties under src/test/resources, which application.properties gets picked up, depends on how you are running your tests. The folder structure src/main/resources and src/test/resources, is a Maven architectural convention, so if you run your test like mvnw test or even gradlew test, the application.properties in src/test/resources will get picked up, as test classpath will precede main classpath. But, if you run your test like Run as JUnit Test in Eclipse/STS, the application.properties in src/main/resources will get picked up, as main classpath precedes test classpath.

You can check it out by opening the menu bar Run > Run Configurations > JUnit > *your_run_configuration* > Click on "Show Command Line".

You will see something like this:

XXXbin\javaw.exe -ea -Dfile.encoding=UTF-8 -classpath
XXX\workspace-spring-tool-suite-4-4.5.1.RELEASE\project_name\bin\main;
XXX\workspace-spring-tool-suite-4-4.5.1.RELEASE\project_name\bin\test;

Do you see that classpath xxx\main comes first, and then xxx\test? Right, it's all about classpath :-)

Side-note: Be mindful that properties overridden in the Launch Configuration(In Spring Tool Suite IDE, for example) takes priority over application.properties.

I just configured min as the following :

spring.h2.console.enabled=true
spring.h2.console.path=/h2-console


# changing the name of my data base for testing
spring.datasource.url= jdbc:h2:mem:mockedDB
spring.datasource.username=sa
spring.datasource.password=sa



# in testing i don`t need to know the port

#Feature that determines what happens when no accessors are found for a type
#(and there are no annotations to indicate it is meant to be serialized).
spring.jackson.serialization.FAIL_ON_EMPTY_BEANS=false`enter code here`

Otherwise we may change the default property configurator name, setting the property spring.config.name=test and then having class-path resource src/test/test.properties our native instance of org.springframework.boot.SpringApplication will be auto-configured from this separated test.properties, ignoring application properties;

Benefit: auto-configuration of tests;

Drawback: exposing "spring.config.name" property at C.I. layer

ref: http://docs.spring.io/spring-boot/docs/current/reference/html/common-application-properties.html

spring.config.name=application # Config file name

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.

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.

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

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

If you're using Spring 5.2.5 and Spring Boot 2.2.6 and want to override just a few properties instead of the whole file. You can use the new annotation: @DynamicPropertySource

@SpringBootTest
@Testcontainers
class ExampleIntegrationTests {

    @Container
    static Neo4jContainer<?> neo4j = new Neo4jContainer<>();

    @DynamicPropertySource
    static void neo4jProperties(DynamicPropertyRegistry registry) {
        registry.add("spring.data.neo4j.uri", neo4j::getBoltUrl);
    }
}