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A versatile Java(TM) library that implements many useful container and utility classes.

There is a newer version: 1.1.12


/*
 * de.unkrig.commons - A general-purpose Java class library
 *
 * Copyright (c) 2014, Arno Unkrig
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
 * following conditions are met:
 *
 *    1. Redistributions of source code must retain the above copyright notice, this list of conditions and the
 *       following disclaimer.
 *    2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
 *       following disclaimer in the documentation and/or other materials provided with the distribution.
 *    3. The name of the author may not be used to endorse or promote products derived from this software without
 *       specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
 * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

package de.unkrig.commons.junit4;

import static org.junit.Assert.assertEquals;

import java.io.OutputStream;

import de.unkrig.commons.lang.AssertionUtil;
import de.unkrig.commons.lang.protocol.Producer;

/**
 * Utility methods related to JUNIT and {@code java.io}.
 */
public final
class AssertIo {

    static { AssertionUtil.enableAssertionsForThisClass(); }

    private AssertIo() {}

    /**
     * @return An output stream which asserts that the data written to it equals the {@code expected} byte sequence
     */
    public static OutputStream
    assertEqualData(final Producer expected) {

        return new OutputStream() {

            int count;

            @Override public void
            write(int b) {
                Byte product = expected.produce();
                assert product != null;
                if ((0xff & product) != (0xff & b)) {
                    assertEquals(this.count + " bytes matched so far", 0xff & product, 0xff & b);
                }
                this.count++;
            }
        };
    }
}