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package org.junit.internal.matchers;
import org.hamcrest.Description;
import org.hamcrest.Factory;
import org.hamcrest.Matcher;
import org.hamcrest.TypeSafeMatcher;
/**
* A matcher that applies a delegate matcher to the cause of the current Throwable, returning the result of that
* match.
*
* @param the type of the throwable being matched
*/
public class ThrowableCauseMatcher extends
TypeSafeMatcher {
private final Matcher causeMatcher;
public ThrowableCauseMatcher(Matcher causeMatcher) {
this.causeMatcher = causeMatcher;
}
public void describeTo(Description description) {
description.appendText("exception with cause ");
description.appendDescriptionOf(causeMatcher);
}
@Override
protected boolean matchesSafely(T item) {
return causeMatcher.matches(item.getCause());
}
@Override
protected void describeMismatchSafely(T item, Description description) {
description.appendText("cause ");
causeMatcher.describeMismatch(item.getCause(), description);
}
/**
* Returns a matcher that verifies that the outer exception has a cause for which the supplied matcher
* evaluates to true.
*
* @param matcher to apply to the cause of the outer exception
* @param type of the outer exception
*/
@Factory
public static Matcher hasCause(final Matcher matcher) {
return new ThrowableCauseMatcher(matcher);
}
}