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JUnit is a unit testing framework for Java, created by Erich Gamma and Kent Beck.

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package org.junit.internal.matchers;

import java.io.PrintWriter;
import java.io.StringWriter;

import org.hamcrest.Description;
import org.hamcrest.Factory;
import org.hamcrest.Matcher;

/**
 * A matcher that delegates to throwableMatcher and in addition appends the
 * stacktrace of the actual Throwable in case of a mismatch.
 */
public class StacktracePrintingMatcher extends
        org.hamcrest.TypeSafeMatcher {

    private final Matcher throwableMatcher;

    public StacktracePrintingMatcher(Matcher throwableMatcher) {
        this.throwableMatcher = throwableMatcher;
    }

    public void describeTo(Description description) {
        throwableMatcher.describeTo(description);
    }

    @Override
    protected boolean matchesSafely(T item) {
        return throwableMatcher.matches(item);
    }

    @Override
    protected void describeMismatchSafely(T item, Description description) {
        throwableMatcher.describeMismatch(item, description);
        description.appendText("\nStacktrace was: ");
        description.appendText(readStacktrace(item));
    }

    private String readStacktrace(Throwable throwable) {
        StringWriter stringWriter = new StringWriter();
        throwable.printStackTrace(new PrintWriter(stringWriter));
        return stringWriter.toString();
    }

    @Factory
    public static  Matcher isThrowable(
            Matcher throwableMatcher) {
        return new StacktracePrintingMatcher(throwableMatcher);
    }

    @Factory
    public static  Matcher isException(
            Matcher exceptionMatcher) {
        return new StacktracePrintingMatcher(exceptionMatcher);
    }
}