MainMethodTests.java

/*
 * Copyright 2012-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot.devtools.restart;

import java.lang.reflect.Method;

import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;

import org.springframework.util.ReflectionUtils;

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

/**
 * Tests for {@link MainMethod}.
 *
 * @author Phillip Webb
 */
public class MainMethodTests {

	@Rule
	public ExpectedException thrown = ExpectedException.none();

	private static ThreadLocal<MainMethod> mainMethod = new ThreadLocal<>();

	private Method actualMain;

	@Before
	public void setup() throws Exception {
		this.actualMain = Valid.class.getMethod("main", String[].class);
	}

	@Test
	public void threadMustNotBeNull() throws Exception {
		this.thrown.expect(IllegalArgumentException.class);
		this.thrown.expectMessage("Thread must not be null");
		new MainMethod(null);
	}

	@Test
	public void validMainMethod() throws Exception {
		MainMethod method = new TestThread(new Runnable() {
			@Override
			public void run() {
				Valid.main();
			}
		}).test();
		assertThat(method.getMethod()).isEqualTo(this.actualMain);
		assertThat(method.getDeclaringClassName())
				.isEqualTo(this.actualMain.getDeclaringClass().getName());
	}

	@Test
	public void missingArgsMainMethod() throws Exception {
		this.thrown.expect(IllegalStateException.class);
		this.thrown.expectMessage("Unable to find main method");
		new TestThread(new Runnable() {
			@Override
			public void run() {
				MissingArgs.main();
			}
		}).test();
	}

	@Test
	public void nonStatic() throws Exception {
		this.thrown.expect(IllegalStateException.class);
		this.thrown.expectMessage("Unable to find main method");
		new TestThread(new Runnable() {
			@Override
			public void run() {
				new NonStaticMain().main();
			}
		}).test();
	}

	private static class TestThread extends Thread {

		private final Runnable runnable;

		private Exception exception;

		private MainMethod mainMethod;

		TestThread(Runnable runnable) {
			this.runnable = runnable;
		}

		public MainMethod test() throws InterruptedException {
			start();
			join();
			if (this.exception != null) {
				ReflectionUtils.rethrowRuntimeException(this.exception);
			}
			return this.mainMethod;
		}

		@Override
		public void run() {
			try {
				this.runnable.run();
				this.mainMethod = MainMethodTests.mainMethod.get();
			}
			catch (Exception ex) {
				this.exception = ex;
			}
		}

	}

	public static class Valid {

		public static void main(String... args) {
			someOtherMethod();
		}

		private static void someOtherMethod() {
			mainMethod.set(new MainMethod());
		}

	}

	public static class MissingArgs {

		public static void main() {
			mainMethod.set(new MainMethod());
		}

	}

	private static class NonStaticMain {

		public void main(String... args) {
			mainMethod.set(new MainMethod());
		}

	}

}