Asserts exception without try-catch or @Test.expected() in junit.

AdditionalAssert.java

package net.kjunine.test;

import static org.junit.Assert.*;

import java.io.IOException;

import org.junit.Test;

public class AdditionalAssert {

  /**
	 * Asserts that expected exception occurs. If it doesn't, an
	 * {@link AssertionError} is thrown.
	 * 
	 * @param expected
	 *            type of the expected exception
	 * @param code
	 *            the code to run
	 */
	public static void assertException(Class<? extends Throwable> expected,
			Code code) {
		try {
			code.test();
			fail("expected: " + expected + ", but no exception occured.");
		} catch (AssertionError e) {
			if (!expected.isAssignableFrom(e.getClass())) {
				throw e;
			}
		} catch (Throwable e) {
			if (!expected.isAssignableFrom(e.getClass())) {
				fail("expected: " + expected + ", but was: " + e.getClass());
			}
		}
	}

	/**
	 * Similar to {@link Runnable}, but this can throw checked exceptions.
	 */
	public static interface Code {

		void test() throws Exception;

	}

  @Test
	public void test() {
		assertException(IllegalArgumentException.class, new Code() {
			public void test() throws Exception {
				throw new IllegalArgumentException();
			}
		});

		assertException(RuntimeException.class, new Code() {
			public void test() throws Exception {
				throw new IllegalArgumentException();
			}
		});

		assertException(AssertionError.class, new Code() {
			public void test() throws Exception {
				assertException(IllegalArgumentException.class, new Code() {
					public void test() throws Exception {
						throw new RuntimeException();
					}
				});
			}
		});

		assertException(IOException.class, new Code() {
			public void test() throws Exception {
				throw new IOException();
			}
		});

		assertException(OutOfMemoryError.class, new Code() {
			public void test() throws Exception {
				throw new OutOfMemoryError();
			}
		});

		assertException(AssertionError.class, new Code() {
			public void test() throws Exception {
				throw new AssertionError();
			}
		});
	}

}