Unit test demonstrating behaviour of apache commons configuration

ReloadablePropertiesTest.java

import org.apache.commons.configuration2.FileBasedConfiguration;
import org.apache.commons.configuration2.PropertiesConfiguration;
import org.apache.commons.configuration2.builder.ConfigurationBuilderEvent;
import org.apache.commons.configuration2.builder.ReloadingFileBasedConfigurationBuilder;
import org.apache.commons.configuration2.builder.fluent.Parameters;
import org.apache.commons.configuration2.event.Event;
import org.apache.commons.configuration2.event.EventListener;
import org.apache.commons.configuration2.ex.ConfigurationException;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;

public class ReloadablePropertiesTest {

	private final String propertyFilePath = "/tmp/test.properties";
	private ReloadingFileBasedConfigurationBuilder<FileBasedConfiguration> builder;

	@Before
	public void setUp() throws FileNotFoundException {
		try (PrintWriter out = new PrintWriter(propertyFilePath)) {
			out.println("test=99");
		}

		File propertiesFile = new File(propertyFilePath);
		builder = new ReloadingFileBasedConfigurationBuilder<FileBasedConfiguration>(PropertiesConfiguration.class)
				.configure(new Parameters().fileBased().setFile(propertiesFile));
		builder.addEventListener(ConfigurationBuilderEvent.CONFIGURATION_REQUEST,
				new EventListener() {
					@Override
					public void onEvent(final Event event) {
						builder.getReloadingController().checkForReloading(null);
					}
				});
	}

	@Test
	public void test() throws InterruptedException, FileNotFoundException, ConfigurationException {
		builder.getConfiguration().getInt("test");
		Assert.assertEquals(99, builder.getConfiguration().getInt("test"));

		Thread.sleep(6_000);
		try (PrintWriter out = new PrintWriter(propertyFilePath)) {
			out.println("test=100");
		}
		Thread.sleep(1_000);
		Assert.assertEquals(100, builder.getConfiguration().getInt("test"));
	}
}