Setting properties before application context starts

MyRunner.java

package com.example;

import org.junit.runner.notification.RunNotifier;
import org.junit.runners.model.InitializationError;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

public class MyRunner extends SpringJUnit4ClassRunner {

    public MyRunner(Class<?> clazz) throws InitializationError {
        super(clazz);
        System.setProperty("sample.property", "hello world!");
    }

}

SpringBootStackApplicationTests.java

package com.example;

import static org.assertj.core.api.Assertions.assertThat;

import org.assertj.core.api.Assertions;
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.core.env.Environment;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(MyRunner.class)
@SpringBootTest
public class SpringBootStackApplicationTests {

	@Autowired
	Environment environment;

	@Test
	public void testIfPropertyPresent() {
		assertThat(environment.getProperty("sample.property")).isEqualTo("hello world!");
	}

}