/*
* Copyright 2002-2012 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.tests;
import org.hamcrest.BaseMatcher;
import org.hamcrest.Description;
import org.hamcrest.Matcher;
import org.junit.Rule;
import org.junit.rules.ExpectedException;
/**
* Additional hamcrest matchers.
*
* @author Phillip Webb
*/
public class Matchers {
/**
* Create a matcher that wrapps the specified matcher and tests against the
* {@link Throwable#getCause() cause} of an exception. If the item tested
* is {@code null} not a {@link Throwable} the wrapped matcher will be called
* with a {@code null} item.
*
* <p>Often useful when working with JUnit {@link ExpectedException}
* {@link Rule @Rule}s, for example:
* <pre>
* thrown.expect(DataAccessException.class);
* thrown.except(exceptionCause(isA(SQLException.class)));
* </pre>
*
* @param matcher the matcher to wrap (must not be null)
* @return a matcher that tests using the exception cause
*/
@SuppressWarnings("unchecked")
public static <T> Matcher<T> exceptionCause(final Matcher<T> matcher) {
return (Matcher<T>) new BaseMatcher<Object>() {
@Override
public boolean matches(Object item) {
Throwable cause = null;
if (item != null && item instanceof Throwable) {
cause = ((Throwable)item).getCause();
}
return matcher.matches(cause);
}
@Override
public void describeTo(Description description) {
description.appendText("exception cause ").appendDescriptionOf(matcher);
}
};
}
}