jdk/test/java/util/Arrays/ParallelPrefix.java - platform/libcore - Git at Google

 /*
  * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */

 /**
  * @test 8014076 8025067
  * @summary unit test for Arrays.ParallelPrefix().
  * @author Tristan Yan
  * @run testng ParallelPrefix
  */

 import java.util.Arrays;
 import java.util.function.BinaryOperator;
 import java.util.function.DoubleBinaryOperator;
 import java.util.function.Function;
 import java.util.function.IntBinaryOperator;
 import java.util.function.LongBinaryOperator;
 import java.util.stream.IntStream;
 import java.util.stream.LongStream;
 import static org.testng.Assert.*;
 import org.testng.annotations.DataProvider;
 import org.testng.annotations.Test;

 public class ParallelPrefix {
     //Array size less than MIN_PARTITION
     private static final int SMALL_ARRAY_SIZE = 1 << 3;

     //Array size equals MIN_PARTITION
     private static final int THRESHOLD_ARRAY_SIZE = 1 << 4;

     //Array size greater than MIN_PARTITION
     private static final int MEDIUM_ARRAY_SIZE = 1 << 8;

     //Array size much greater than MIN_PARTITION
     private static final int LARGE_ARRAY_SIZE = 1 << 14;

     private static final int[] ARRAY_SIZE_COLLECTION  = new int[]{
         SMALL_ARRAY_SIZE,
         THRESHOLD_ARRAY_SIZE,
         MEDIUM_ARRAY_SIZE,
         LARGE_ARRAY_SIZE
     };

     @DataProvider(name = "intSet")
     public static Object[][] intSet(){
         return genericData(size -> IntStream.range(0, size).toArray(),
                 new IntBinaryOperator[]{
                     Integer::sum,
                     Integer::min});
     }

     @DataProvider(name = "longSet")
     public static Object[][] longSet(){
         return genericData(size -> LongStream.range(0, size).toArray(),
                 new LongBinaryOperator[]{
                     Long::sum,
                     Long::min});
     }

     @DataProvider(name = "doubleSet")
     public static Object[][] doubleSet(){
         return genericData(size -> IntStream.range(0, size).mapToDouble(i -> (double)i).toArray(),
                 new DoubleBinaryOperator[]{
                     Double::sum,
                     Double::min});
     }

     @DataProvider(name = "stringSet")
     public static Object[][] stringSet(){
         Function<Integer, String[]> stringsFunc = size ->
                 IntStream.range(0, size).mapToObj(Integer::toString).toArray(String[]::new);
         BinaryOperator<String> concat = String::concat;
         return genericData(stringsFunc,
                 (BinaryOperator<String>[]) new BinaryOperator[]{
                     concat });
     }

     private static <T, OPS> Object[][] genericData(Function<Integer, T> generateFunc, OPS[] ops) {
         //test arrays which size is equals n-1, n, n+1, test random data
         Object[][] data = new Object[ARRAY_SIZE_COLLECTION.length * 3 * ops.length][4];
         for(int n = 0; n < ARRAY_SIZE_COLLECTION.length; n++ ) {
             for(int testValue = -1 ; testValue <= 1; testValue++) {
                 int array_size = ARRAY_SIZE_COLLECTION[n] + testValue;
                 for(int opsN = 0; opsN < ops.length; opsN++) {
                     int index = n * 3 * ops.length + (testValue + 1) * ops.length + opsN;
                     data[index][0] = generateFunc.apply(array_size);
                     data[index][1] = array_size / 3;
                     data[index][2] = 2 * array_size / 3;
                     data[index][3] = ops[opsN];
                 }
             }
         }
         return data;
     }

     @Test(dataProvider="intSet")
     public void testParallelPrefixForInt(int[] data, int fromIndex, int toIndex, IntBinaryOperator op) {
         int[] sequentialResult = data.clone();
         for (int index = fromIndex + 1; index < toIndex; index++) {
             sequentialResult[index ] = op.applyAsInt(sequentialResult[index  - 1], sequentialResult[index]);
         }

         int[] parallelResult = data.clone();
         Arrays.parallelPrefix(parallelResult, fromIndex, toIndex, op);
         assertArraysEqual(parallelResult, sequentialResult);

         int[] parallelRangeResult = Arrays.copyOfRange(data, fromIndex, toIndex);
         Arrays.parallelPrefix(parallelRangeResult, op);
         assertArraysEqual(parallelRangeResult, Arrays.copyOfRange(sequentialResult, fromIndex, toIndex));
     }

     @Test(dataProvider="longSet")
     public void testParallelPrefixForLong(long[] data, int fromIndex, int toIndex, LongBinaryOperator op) {
         long[] sequentialResult = data.clone();
         for (int index = fromIndex + 1; index < toIndex; index++) {
             sequentialResult[index ] = op.applyAsLong(sequentialResult[index  - 1], sequentialResult[index]);
         }

         long[] parallelResult = data.clone();
         Arrays.parallelPrefix(parallelResult, fromIndex, toIndex, op);
         assertArraysEqual(parallelResult, sequentialResult);

         long[] parallelRangeResult = Arrays.copyOfRange(data, fromIndex, toIndex);
         Arrays.parallelPrefix(parallelRangeResult, op);
         assertArraysEqual(parallelRangeResult, Arrays.copyOfRange(sequentialResult, fromIndex, toIndex));
     }

     @Test(dataProvider="doubleSet")
     public void testParallelPrefixForDouble(double[] data, int fromIndex, int toIndex, DoubleBinaryOperator op) {
         double[] sequentialResult = data.clone();
         for (int index = fromIndex + 1; index < toIndex; index++) {
             sequentialResult[index ] = op.applyAsDouble(sequentialResult[index  - 1], sequentialResult[index]);
         }

         double[] parallelResult = data.clone();
         Arrays.parallelPrefix(parallelResult, fromIndex, toIndex, op);
         assertArraysEqual(parallelResult, sequentialResult);

         double[] parallelRangeResult = Arrays.copyOfRange(data, fromIndex, toIndex);
         Arrays.parallelPrefix(parallelRangeResult, op);
         assertArraysEqual(parallelRangeResult, Arrays.copyOfRange(sequentialResult, fromIndex, toIndex));
     }

     @Test(dataProvider="stringSet")
     public void testParallelPrefixForStringr(String[] data , int fromIndex, int toIndex, BinaryOperator<String> op) {
         String[] sequentialResult = data.clone();
         for (int index = fromIndex + 1; index < toIndex; index++) {
             sequentialResult[index ] = op.apply(sequentialResult[index  - 1], sequentialResult[index]);
         }

         String[] parallelResult = data.clone();
         Arrays.parallelPrefix(parallelResult, fromIndex, toIndex, op);
         assertArraysEqual(parallelResult, sequentialResult);

         String[] parallelRangeResult = Arrays.copyOfRange(data, fromIndex, toIndex);
         Arrays.parallelPrefix(parallelRangeResult, op);
         assertArraysEqual(parallelRangeResult, Arrays.copyOfRange(sequentialResult, fromIndex, toIndex));
     }

     @Test
     public void testNPEs() {
         // null array
         assertThrows( () -> Arrays.parallelPrefix((int[]) null, Integer::max),
                 NullPointerException.class, "should throw NPE");
         assertThrows( () -> Arrays.parallelPrefix((long []) null, Long::max),
                 NullPointerException.class, "should throw NPE");
         assertThrows( () -> Arrays.parallelPrefix((double []) null, Double::max),
                 NullPointerException.class, "should throw NPE");
         assertThrows( () -> Arrays.parallelPrefix((String []) null, String::concat),
                 NullPointerException.class, "should throw NPE");

         // null array w/ range
         assertThrows( () -> Arrays.parallelPrefix((int[]) null, 0, 0, Integer::max),
                 NullPointerException.class, "should throw NPE");
         assertThrows( () -> Arrays.parallelPrefix((long []) null, 0, 0, Long::max),
                 NullPointerException.class, "should throw NPE");
         assertThrows( () -> Arrays.parallelPrefix((double []) null, 0, 0, Double::max),
                 NullPointerException.class, "should throw NPE");
         assertThrows( () -> Arrays.parallelPrefix((String []) null, 0, 0, String::concat),
                 NullPointerException.class, "should throw NPE");

         // null op
         assertThrows( () -> Arrays.parallelPrefix(new int[] {}, null),
                 NullPointerException.class, "should throw NPE");
         assertThrows( () -> Arrays.parallelPrefix(new long[] {}, null),
                 NullPointerException.class, "should throw NPE");
         assertThrows( () -> Arrays.parallelPrefix(new double[] {}, null),
                 NullPointerException.class, "should throw NPE");
         assertThrows( () -> Arrays.parallelPrefix(new String[] {}, null),
                 NullPointerException.class, "should throw NPE");

         // null op w/ range
         assertThrows( () -> Arrays.parallelPrefix(new int[] {}, 0, 0, null),
                 NullPointerException.class, "should throw NPE");
         assertThrows( () -> Arrays.parallelPrefix(new long[] {}, 0, 0, null),
                 NullPointerException.class, "should throw NPE");
         assertThrows( () -> Arrays.parallelPrefix(new double[] {}, 0, 0, null),
                 NullPointerException.class, "should throw NPE");
         assertThrows( () -> Arrays.parallelPrefix(new String[] {}, 0, 0, null),
                 NullPointerException.class, "should throw NPE");
     }

     @Test
     public void testIAEs() {
         assertThrows( () -> Arrays.parallelPrefix(new int[] {}, 1, 0, Integer::max),
                 IllegalArgumentException.class, "should throw IAE");
         assertThrows( () -> Arrays.parallelPrefix(new long[] {}, 1, 0, Long::max),
                 IllegalArgumentException.class, "should throw IAE");
         assertThrows( () -> Arrays.parallelPrefix(new double[] {}, 1, 0, Double::max),
                 IllegalArgumentException.class, "should throw IAE");
         assertThrows( () -> Arrays.parallelPrefix(new String[] {}, 1, 0, String::concat),
                 IllegalArgumentException.class, "should throw IAE");
     }

     @Test
     public void testAIOBEs() {
         // bad "fromIndex"
         assertThrows( () -> Arrays.parallelPrefix(new int[] {}, -1, 0, Integer::max),
                 ArrayIndexOutOfBoundsException.class, "should throw AIOBE");
         assertThrows( () -> Arrays.parallelPrefix(new long[] {}, -1, 0, Long::max),
                 ArrayIndexOutOfBoundsException.class, "should throw AIOBE");
         assertThrows( () -> Arrays.parallelPrefix(new double[] {}, -1, 0, Double::max),
                 ArrayIndexOutOfBoundsException.class, "should throw AIOBE");
         assertThrows( () -> Arrays.parallelPrefix(new String[] {}, -1, 0, String::concat),
                 ArrayIndexOutOfBoundsException.class, "should throw AIOBE");

         // bad "toIndex"
         assertThrows( () -> Arrays.parallelPrefix(new int[] {}, 0, 1, Integer::max),
                 ArrayIndexOutOfBoundsException.class, "should throw AIOBE");
         assertThrows( () -> Arrays.parallelPrefix(new long[] {}, 0, 1, Long::max),
                 ArrayIndexOutOfBoundsException.class, "should throw AIOBE");
         assertThrows( () -> Arrays.parallelPrefix(new double[] {}, 0, 1, Double::max),
                 ArrayIndexOutOfBoundsException.class, "should throw AIOBE");
         assertThrows( () -> Arrays.parallelPrefix(new String[] {}, 0, 1, String::concat),
                 ArrayIndexOutOfBoundsException.class, "should throw AIOBE");
     }

     // "library" code

     public interface Thrower<T extends Throwable> {

         public void run() throws T;
     }


     public static <T extends Throwable> void assertThrows(Thrower<T> thrower, Class<T> throwable) {
         assertThrows(thrower, throwable, null);
     }

     public static <T extends Throwable> void assertThrows(Thrower<T> thrower, Class<T> throwable, String message) {
         Throwable thrown;
         try {
             thrower.run();
             thrown = null;
         } catch (Throwable caught) {
             thrown = caught;
         }

         assertInstance(thrown, throwable,
             ((null != message) ? message : "") +
             " Failed to throw " + throwable.getCanonicalName());
     }

     public static <T extends Throwable> void assertThrows(Class<T> throwable, String message, Thrower<T>... throwers) {
         for(Thrower<T> thrower : throwers) {
             assertThrows(thrower, throwable, message);
         }
     }

     public static void assertInstance(Object actual, Class<?> expected) {
         assertInstance(expected.isInstance(actual), null);
     }

     public static void assertInstance(Object actual, Class<?> expected, String message) {
         assertTrue(expected.isInstance(actual), message);
     }

     static void assertArraysEqual(int[] actual, int[] expected) {
         try {
             assertEquals(actual, expected, "");
         } catch (AssertionError x) {
             throw new AssertionError(String.format("Expected:%s, actual:%s",
                     Arrays.toString(expected), Arrays.toString(actual)), x);
         }
     }

     static void assertArraysEqual(long[] actual, long[] expected) {
         try {
             assertEquals(actual, expected, "");
         } catch (AssertionError x) {
             throw new AssertionError(String.format("Expected:%s, actual:%s",
                     Arrays.toString(expected), Arrays.toString(actual)), x);
         }
     }

     static void assertArraysEqual(double[] actual, double[] expected) {
         try {
             assertEquals(actual, expected, "");
         } catch (AssertionError x) {
             throw new AssertionError(String.format("Expected:%s, actual:%s",
                     Arrays.toString(expected), Arrays.toString(actual)), x);
         }
     }

     static void assertArraysEqual(String[] actual, String[] expected) {
         try {
             assertEquals(actual, expected, "");
         } catch (AssertionError x) {
             throw new AssertionError(String.format("Expected:%s, actual:%s",
                     Arrays.toString(expected), Arrays.toString(actual)), x);
         }
     }
 }
	/*
	* Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	/**
	* @test 8014076 8025067
	* @summary unit test for Arrays.ParallelPrefix().
	* @author Tristan Yan
	* @run testng ParallelPrefix
	*/

	import java.util.Arrays;
	import java.util.function.BinaryOperator;
	import java.util.function.DoubleBinaryOperator;
	import java.util.function.Function;
	import java.util.function.IntBinaryOperator;
	import java.util.function.LongBinaryOperator;
	import java.util.stream.IntStream;
	import java.util.stream.LongStream;
	import static org.testng.Assert.*;
	import org.testng.annotations.DataProvider;
	import org.testng.annotations.Test;

	public class ParallelPrefix {
	//Array size less than MIN_PARTITION
	private static final int SMALL_ARRAY_SIZE = 1 << 3;

	//Array size equals MIN_PARTITION
	private static final int THRESHOLD_ARRAY_SIZE = 1 << 4;

	//Array size greater than MIN_PARTITION
	private static final int MEDIUM_ARRAY_SIZE = 1 << 8;

	//Array size much greater than MIN_PARTITION
	private static final int LARGE_ARRAY_SIZE = 1 << 14;

	private static final int[] ARRAY_SIZE_COLLECTION = new int[]{
	SMALL_ARRAY_SIZE,
	THRESHOLD_ARRAY_SIZE,
	MEDIUM_ARRAY_SIZE,
	LARGE_ARRAY_SIZE
	};

	@DataProvider(name = "intSet")
	public static Object[][] intSet(){
	return genericData(size -> IntStream.range(0, size).toArray(),
	new IntBinaryOperator[]{
	Integer::sum,
	Integer::min});
	}

	@DataProvider(name = "longSet")
	public static Object[][] longSet(){
	return genericData(size -> LongStream.range(0, size).toArray(),
	new LongBinaryOperator[]{
	Long::sum,
	Long::min});
	}

	@DataProvider(name = "doubleSet")
	public static Object[][] doubleSet(){
	return genericData(size -> IntStream.range(0, size).mapToDouble(i -> (double)i).toArray(),
	new DoubleBinaryOperator[]{
	Double::sum,
	Double::min});
	}

	@DataProvider(name = "stringSet")
	public static Object[][] stringSet(){
	Function<Integer, String[]> stringsFunc = size ->
	IntStream.range(0, size).mapToObj(Integer::toString).toArray(String[]::new);
	BinaryOperator<String> concat = String::concat;
	return genericData(stringsFunc,
	(BinaryOperator<String>[]) new BinaryOperator[]{
	concat });
	}

	private static <T, OPS> Object[][] genericData(Function<Integer, T> generateFunc, OPS[] ops) {
	//test arrays which size is equals n-1, n, n+1, test random data
	Object[][] data = new Object[ARRAY_SIZE_COLLECTION.length * 3 * ops.length][4];
	for(int n = 0; n < ARRAY_SIZE_COLLECTION.length; n++ ) {
	for(int testValue = -1 ; testValue <= 1; testValue++) {
	int array_size = ARRAY_SIZE_COLLECTION[n] + testValue;
	for(int opsN = 0; opsN < ops.length; opsN++) {
	int index = n * 3 * ops.length + (testValue + 1) * ops.length + opsN;
	data[index][0] = generateFunc.apply(array_size);
	data[index][1] = array_size / 3;
	data[index][2] = 2 * array_size / 3;
	data[index][3] = ops[opsN];
	}
	}
	}
	return data;
	}

	@Test(dataProvider="intSet")
	public void testParallelPrefixForInt(int[] data, int fromIndex, int toIndex, IntBinaryOperator op) {
	int[] sequentialResult = data.clone();
	for (int index = fromIndex + 1; index < toIndex; index++) {
	sequentialResult[index ] = op.applyAsInt(sequentialResult[index - 1], sequentialResult[index]);
	}

	int[] parallelResult = data.clone();
	Arrays.parallelPrefix(parallelResult, fromIndex, toIndex, op);
	assertArraysEqual(parallelResult, sequentialResult);

	int[] parallelRangeResult = Arrays.copyOfRange(data, fromIndex, toIndex);
	Arrays.parallelPrefix(parallelRangeResult, op);
	assertArraysEqual(parallelRangeResult, Arrays.copyOfRange(sequentialResult, fromIndex, toIndex));
	}

	@Test(dataProvider="longSet")
	public void testParallelPrefixForLong(long[] data, int fromIndex, int toIndex, LongBinaryOperator op) {
	long[] sequentialResult = data.clone();
	for (int index = fromIndex + 1; index < toIndex; index++) {
	sequentialResult[index ] = op.applyAsLong(sequentialResult[index - 1], sequentialResult[index]);
	}

	long[] parallelResult = data.clone();
	Arrays.parallelPrefix(parallelResult, fromIndex, toIndex, op);
	assertArraysEqual(parallelResult, sequentialResult);

	long[] parallelRangeResult = Arrays.copyOfRange(data, fromIndex, toIndex);
	Arrays.parallelPrefix(parallelRangeResult, op);
	assertArraysEqual(parallelRangeResult, Arrays.copyOfRange(sequentialResult, fromIndex, toIndex));
	}

	@Test(dataProvider="doubleSet")
	public void testParallelPrefixForDouble(double[] data, int fromIndex, int toIndex, DoubleBinaryOperator op) {
	double[] sequentialResult = data.clone();
	for (int index = fromIndex + 1; index < toIndex; index++) {
	sequentialResult[index ] = op.applyAsDouble(sequentialResult[index - 1], sequentialResult[index]);
	}

	double[] parallelResult = data.clone();
	Arrays.parallelPrefix(parallelResult, fromIndex, toIndex, op);
	assertArraysEqual(parallelResult, sequentialResult);

	double[] parallelRangeResult = Arrays.copyOfRange(data, fromIndex, toIndex);
	Arrays.parallelPrefix(parallelRangeResult, op);
	assertArraysEqual(parallelRangeResult, Arrays.copyOfRange(sequentialResult, fromIndex, toIndex));
	}

	@Test(dataProvider="stringSet")
	public void testParallelPrefixForStringr(String[] data , int fromIndex, int toIndex, BinaryOperator<String> op) {
	String[] sequentialResult = data.clone();
	for (int index = fromIndex + 1; index < toIndex; index++) {
	sequentialResult[index ] = op.apply(sequentialResult[index - 1], sequentialResult[index]);
	}

	String[] parallelResult = data.clone();
	Arrays.parallelPrefix(parallelResult, fromIndex, toIndex, op);
	assertArraysEqual(parallelResult, sequentialResult);

	String[] parallelRangeResult = Arrays.copyOfRange(data, fromIndex, toIndex);
	Arrays.parallelPrefix(parallelRangeResult, op);
	assertArraysEqual(parallelRangeResult, Arrays.copyOfRange(sequentialResult, fromIndex, toIndex));
	}

	@Test
	public void testNPEs() {
	// null array
	assertThrows( () -> Arrays.parallelPrefix((int[]) null, Integer::max),
	NullPointerException.class, "should throw NPE");
	assertThrows( () -> Arrays.parallelPrefix((long []) null, Long::max),
	NullPointerException.class, "should throw NPE");
	assertThrows( () -> Arrays.parallelPrefix((double []) null, Double::max),
	NullPointerException.class, "should throw NPE");
	assertThrows( () -> Arrays.parallelPrefix((String []) null, String::concat),
	NullPointerException.class, "should throw NPE");

	// null array w/ range
	assertThrows( () -> Arrays.parallelPrefix((int[]) null, 0, 0, Integer::max),
	NullPointerException.class, "should throw NPE");
	assertThrows( () -> Arrays.parallelPrefix((long []) null, 0, 0, Long::max),
	NullPointerException.class, "should throw NPE");
	assertThrows( () -> Arrays.parallelPrefix((double []) null, 0, 0, Double::max),
	NullPointerException.class, "should throw NPE");
	assertThrows( () -> Arrays.parallelPrefix((String []) null, 0, 0, String::concat),
	NullPointerException.class, "should throw NPE");

	// null op
	assertThrows( () -> Arrays.parallelPrefix(new int[] {}, null),
	NullPointerException.class, "should throw NPE");
	assertThrows( () -> Arrays.parallelPrefix(new long[] {}, null),
	NullPointerException.class, "should throw NPE");
	assertThrows( () -> Arrays.parallelPrefix(new double[] {}, null),
	NullPointerException.class, "should throw NPE");
	assertThrows( () -> Arrays.parallelPrefix(new String[] {}, null),
	NullPointerException.class, "should throw NPE");

	// null op w/ range
	assertThrows( () -> Arrays.parallelPrefix(new int[] {}, 0, 0, null),
	NullPointerException.class, "should throw NPE");
	assertThrows( () -> Arrays.parallelPrefix(new long[] {}, 0, 0, null),
	NullPointerException.class, "should throw NPE");
	assertThrows( () -> Arrays.parallelPrefix(new double[] {}, 0, 0, null),
	NullPointerException.class, "should throw NPE");
	assertThrows( () -> Arrays.parallelPrefix(new String[] {}, 0, 0, null),
	NullPointerException.class, "should throw NPE");
	}

	@Test
	public void testIAEs() {
	assertThrows( () -> Arrays.parallelPrefix(new int[] {}, 1, 0, Integer::max),
	IllegalArgumentException.class, "should throw IAE");
	assertThrows( () -> Arrays.parallelPrefix(new long[] {}, 1, 0, Long::max),
	IllegalArgumentException.class, "should throw IAE");
	assertThrows( () -> Arrays.parallelPrefix(new double[] {}, 1, 0, Double::max),
	IllegalArgumentException.class, "should throw IAE");
	assertThrows( () -> Arrays.parallelPrefix(new String[] {}, 1, 0, String::concat),
	IllegalArgumentException.class, "should throw IAE");
	}

	@Test
	public void testAIOBEs() {
	// bad "fromIndex"
	assertThrows( () -> Arrays.parallelPrefix(new int[] {}, -1, 0, Integer::max),
	ArrayIndexOutOfBoundsException.class, "should throw AIOBE");
	assertThrows( () -> Arrays.parallelPrefix(new long[] {}, -1, 0, Long::max),
	ArrayIndexOutOfBoundsException.class, "should throw AIOBE");
	assertThrows( () -> Arrays.parallelPrefix(new double[] {}, -1, 0, Double::max),
	ArrayIndexOutOfBoundsException.class, "should throw AIOBE");
	assertThrows( () -> Arrays.parallelPrefix(new String[] {}, -1, 0, String::concat),
	ArrayIndexOutOfBoundsException.class, "should throw AIOBE");

	// bad "toIndex"
	assertThrows( () -> Arrays.parallelPrefix(new int[] {}, 0, 1, Integer::max),
	ArrayIndexOutOfBoundsException.class, "should throw AIOBE");
	assertThrows( () -> Arrays.parallelPrefix(new long[] {}, 0, 1, Long::max),
	ArrayIndexOutOfBoundsException.class, "should throw AIOBE");
	assertThrows( () -> Arrays.parallelPrefix(new double[] {}, 0, 1, Double::max),
	ArrayIndexOutOfBoundsException.class, "should throw AIOBE");
	assertThrows( () -> Arrays.parallelPrefix(new String[] {}, 0, 1, String::concat),
	ArrayIndexOutOfBoundsException.class, "should throw AIOBE");
	}

	// "library" code

	public interface Thrower<T extends Throwable> {

	public void run() throws T;
	}


	public static <T extends Throwable> void assertThrows(Thrower<T> thrower, Class<T> throwable) {
	assertThrows(thrower, throwable, null);
	}

	public static <T extends Throwable> void assertThrows(Thrower<T> thrower, Class<T> throwable, String message) {
	Throwable thrown;
	try {
	thrower.run();
	thrown = null;
	} catch (Throwable caught) {
	thrown = caught;
	}

	assertInstance(thrown, throwable,
	((null != message) ? message : "") +
	" Failed to throw " + throwable.getCanonicalName());
	}

	public static <T extends Throwable> void assertThrows(Class<T> throwable, String message, Thrower<T>... throwers) {
	for(Thrower<T> thrower : throwers) {
	assertThrows(thrower, throwable, message);
	}
	}

	public static void assertInstance(Object actual, Class<?> expected) {
	assertInstance(expected.isInstance(actual), null);
	}

	public static void assertInstance(Object actual, Class<?> expected, String message) {
	assertTrue(expected.isInstance(actual), message);
	}

	static void assertArraysEqual(int[] actual, int[] expected) {
	try {
	assertEquals(actual, expected, "");
	} catch (AssertionError x) {
	throw new AssertionError(String.format("Expected:%s, actual:%s",
	Arrays.toString(expected), Arrays.toString(actual)), x);
	}
	}

	static void assertArraysEqual(long[] actual, long[] expected) {
	try {
	assertEquals(actual, expected, "");
	} catch (AssertionError x) {
	throw new AssertionError(String.format("Expected:%s, actual:%s",
	Arrays.toString(expected), Arrays.toString(actual)), x);
	}
	}

	static void assertArraysEqual(double[] actual, double[] expected) {
	try {
	assertEquals(actual, expected, "");
	} catch (AssertionError x) {
	throw new AssertionError(String.format("Expected:%s, actual:%s",
	Arrays.toString(expected), Arrays.toString(actual)), x);
	}
	}

	static void assertArraysEqual(String[] actual, String[] expected) {
	try {
	assertEquals(actual, expected, "");
	} catch (AssertionError x) {
	throw new AssertionError(String.format("Expected:%s, actual:%s",
	Arrays.toString(expected), Arrays.toString(actual)), x);
	}
	}
	}