[JAVA] Workaround for Command Line Runner to work with JUnit in Spring Boot

Background and problems

In Spring Boot, use Command Line Runner You can develop applications that run from the command line.

But in an application that uses CommandLineRunner When you run a test in JUnit, not only the test code but also the processing of CommandLineRunner itself is executed.

I felt a little crazy, so I wanted to avoid it somehow.

Execution environment

• Spring Boot-2.0.2.RELEASE
• JUnit-4.12

Execution code and test and output

Execution code

SampleApplication.java

package com.example.demo;

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

@SpringBootApplication
public class SampleApplication implements CommandLineRunner {

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

  @Override
  public void run(String... arg) {
    SampleOutput sample = new SampleOutput();
    System.out.println(sample.sayTest());
    System.out.println("!!!Sample CommandLineRunner Start!!!");
  }
}

SampleOutput.java

package com.example.demo;

public class SampleOutput {

  public String sayTest() {
    return "test!!";
  }
}

Test code

SampleOutputTest

package com.example.demo;

import static org.junit.Assert.assertEquals;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

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

	@Test
	public void testTest() {
	  SampleOutput sample = new SampleOutput();
	  assertEquals("test!!", sample.sayTest());
	}
}

The result of running JUnit is as follows.

Execution result

07:42:33.780 [main] DEBUG org.springframework.test.context.junit4.SpringJUnit4ClassRunner - SpringJUnit4ClassRunner constructor called with [class com.example.demo.SampleOutputTest]

abridgement

2018-06-13 07:42:34.458  INFO 6564 --- [           main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@2df9b86: startup date [Wed Jun 13 07:42:34 JST 2018]; root of context hierarchy
2018-06-13 07:42:35.128  INFO 6564 --- [           main] com.example.demo.SampleOutputTest        : Started SampleOutputTest in 0.972 seconds (JVM running for 1.867)
test!!
!!!Sample CommandLineRunner Start!!!
2018-06-13 07:42:35.190  INFO 6564 --- [       Thread-2] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@2df9b86: startup date [Wed Jun 13 07:42:34 JST 2018]; root of context hierarchy

When I run JUnit, it outputs with CommandLineRunner

test!!
!!!Sample CommandLineRunner Start!!!

Is output. I want only the test code to work, but even CommandLineRunner has been executed.

Workaround

I don't want to run CommandLineRunner when running JUnit, so I'll look for a way to do it. Try it referring to the following. https://stackoverflow.com/questions/29344313/prevent-application-commandlinerunner-classes-from-executing-during-junit-test

Use Profile annotation

This method is omitted because there are easy-to-understand articles on stackoverflow and Qiita. https://qiita.com/ftsan/items/80b00f8fb8129ecbdf97

However, I wonder if there is a different method I tried to see if there was another way that I could just fix the test code.

Use ContextConfiguration annotation

In the test code SampleOutputTest.java Annotate SpringBootTest ContextConfiguration(classes = SampleApplication.class, initializers = ConfigFileApplicationContextInitializer.class) Modify to annotation.

SampleOutputTest.java

@RunWith(SpringRunner.class)
@ContextConfiguration(classes = SampleApplication.class, 
initializers = ConfigFileApplicationContextInitializer.class)
public class SampleOutputTest {

Now when you run the test, you can test it without running CommandLineRunner. The classes = SampleApplication.class part specifies the class where the main method is located.

Execution result

07:44:49.301 [main] DEBUG org.springframework.test.context.junit4.SpringJUnit4ClassRunner - SpringJUnit4ClassRunner constructor called with [class com.example.demo.SampleOutputTest]

Omitted below

Now you can test without running CommandLineRunner with just the modification of the test code. Does it mean that SpringBootTest is loading various settings, but ContextConfiguration does not load all the settings?

https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-testing.html If you read this document carefully, you can find it at 43.4 Test Utilities. It was written that you should use this if you do not need to use all the functions of SpringBootTest.

@ContextConfiguration(classes = Config.class,
	initializers = ConfigFileApplicationContextInitializer.class)