Using the Test Configuration Main Method

Typically the test configuration discovered by @SpringBootTest will be your main @SpringBootApplication. In most well structured applications, this configuration class will also include the main method used to launch the application.

For example, the following is a very common code pattern for a typical Spring Boot application:

Java
Kotlin

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class MyApplication {

	public static void main(String[] args) {
		SpringApplication.run(MyApplication.class, args);
	}

}

import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.docs.using.structuringyourcode.locatingthemainclass.MyApplication
import org.springframework.boot.runApplication

@SpringBootApplication
class MyApplication

fun main(args: Array<String>) {
	runApplication<MyApplication>(*args)
}

In the example above, the main method doesn’t do anything other than delegate to SpringApplication.run. It is, however, possible to have a more complex main method that applies customizations before calling SpringApplication.run.

For example, here is an application that changes the banner mode and sets additional profiles:

Java
Kotlin

import org.springframework.boot.Banner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class MyApplication {

	public static void main(String[] args) {
		SpringApplication application = new SpringApplication(MyApplication.class);
		application.setBannerMode(Banner.Mode.OFF);
		application.setAdditionalProfiles("myprofile");
		application.run(args);
	}

}

import org.springframework.boot.Banner
import org.springframework.boot.runApplication
import org.springframework.boot.autoconfigure.SpringBootApplication

@SpringBootApplication
class MyApplication

fun main(args: Array<String>) {
	runApplication<MyApplication>(*args) {
		setBannerMode(Banner.Mode.OFF)
		setAdditionalProfiles("myprofile");
	}
}

Since customizations in the main method can affect the resulting ApplicationContext, it’s possible that you might also want to use the main method to create the ApplicationContext used in your tests. By default, @SpringBootTest will not call your main method, and instead the class itself is used directly to create the ApplicationContext

If you want to change this behavior, you can change the useMainMethod attribute of @SpringBootTest to UseMainMethod.ALWAYS or UseMainMethod.WHEN_AVAILABLE. When set to ALWAYS, the test will fail if no main method can be found. When set to WHEN_AVAILABLE the main method will be used if it is available, otherwise the standard loading mechanism will be used.

For example, the following test will invoke the main method of MyApplication in order to create the ApplicationContext. If the main method sets additional profiles then those will be active when the ApplicationContext starts.

Java
Kotlin

import org.junit.jupiter.api.Test;

import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.context.SpringBootTest.UseMainMethod;

@SpringBootTest(useMainMethod = UseMainMethod.ALWAYS)
class MyApplicationTests {

	@Test
	void exampleTest() {
		// ...
	}

}

import org.junit.jupiter.api.Test
import org.springframework.boot.test.context.SpringBootTest
import org.springframework.boot.test.context.SpringBootTest.UseMainMethod
import org.springframework.context.annotation.Import

@SpringBootTest(useMainMethod = UseMainMethod.ALWAYS)
class MyApplicationTests {

	@Test
	fun exampleTest() {
		// ...
	}

}