jdk/test/java/util/Collections/EmptyNavigableSet.java - edge/openjdk - Git at Google

 /*
  * Copyright (c) 2011, 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
  * @bug 4533691 7129185
  * @summary Unit test for Collections.emptyNavigableSet
  * @run testng EmptyNavigableSet
  */
 import java.math.BigInteger;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 import java.util.NavigableSet;
 import java.util.SortedSet;
 import java.util.TreeSet;
 import org.testng.annotations.Test;
 import org.testng.annotations.DataProvider;

 import static org.testng.Assert.fail;
 import static org.testng.Assert.assertEquals;
 import static org.testng.Assert.assertTrue;
 import static org.testng.Assert.assertFalse;
 import static org.testng.Assert.assertSame;

 public class EmptyNavigableSet {

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

     public static <T> void assertInstance(T actual, Class<? extends T> expected, String message) {
         assertTrue(expected.isInstance(actual), ((null != message) ? message : "")
             + " " + (actual == null ? "<null>" : actual.getClass().getSimpleName()) + " != " + expected.getSimpleName() + ". ");
     }

     public static <T extends Throwable> void assertEmptyNavigableSet(Object obj) {
         assertInstance(obj, NavigableSet.class);
         assertTrue(((NavigableSet)obj).isEmpty() && (((NavigableSet)obj).size() == 0));
     }

     public static <T extends Throwable> void assertEmptyNavigableSet(Object obj, String message) {
         assertInstance(obj, NavigableSet.class, message);
         assertTrue(((NavigableSet)obj).isEmpty() && (((NavigableSet)obj).size() == 0),
             ((null != message) ? message : "") + " Not empty. ");
     }

     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 result;
         try {
             thrower.run();
             fail(((null != message) ? message : "") + "Failed to throw " + throwable.getCanonicalName() + ". ");
             return;
         } catch (Throwable caught) {
             result = caught;
         }

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

     public static final boolean isDescending(SortedSet<?> set) {
         if (null == set.comparator()) {
             // natural order
             return false;
         }

         if (Collections.reverseOrder() == set.comparator()) {
             // reverse natural order.
             return true;
         }

         if (set.comparator().equals(Collections.reverseOrder(Collections.reverseOrder(set.comparator())))) {
             // it's a Collections.reverseOrder(Comparator).
             return true;
         }

         throw new IllegalStateException("can't determine ordering for " + set);
     }

     /**
      * Tests that the comparator is {@code null}.
      */
     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testComparatorIsNull(String description, NavigableSet<?> navigableSet) {
         Comparator comparator = navigableSet.comparator();

         assertTrue(comparator == null || comparator == Collections.reverseOrder(), description + ": Comparator (" + comparator + ") is not null.");
     }

     /**
      * Tests that contains requires Comparable
      */
     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testContainsRequiresComparable(String description, NavigableSet<?> navigableSet) {
         assertThrows(() -> {
             navigableSet.contains(new Object());
         },
             ClassCastException.class,
             description + ": Compareable should be required");
     }

     /**
      * Tests that the contains method returns {@code false}.
      */
     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testContains(String description, NavigableSet<?> navigableSet) {
         assertFalse(navigableSet.contains(new Integer(1)),
             description + ": Should not contain any elements.");
     }

     /**
      * Tests that the containsAll method returns {@code false}.
      */
     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testContainsAll(String description, NavigableSet<?> navigableSet) {
         TreeSet treeSet = new TreeSet();
         treeSet.add("1");
         treeSet.add("2");
         treeSet.add("3");

         assertFalse(navigableSet.containsAll(treeSet), "Should not contain any elements.");
     }

     /**
      * Tests that the iterator is empty.
      */
     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testEmptyIterator(String description, NavigableSet<?> navigableSet) {
         Iterator emptyIterator = navigableSet.iterator();

         assertFalse((emptyIterator != null) && (emptyIterator.hasNext()),
             "The iterator is not empty.");
     }

     /**
      * Tests that the set is empty.
      */
     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testIsEmpty(String description, NavigableSet<?> navigableSet) {
         assertTrue(navigableSet.isEmpty(), "The set is not empty.");
     }

     /**
      * Tests that the first() method throws NoSuchElementException
      */
     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testFirst(String description, NavigableSet<?> navigableSet) {
         assertThrows(() -> {
             navigableSet.first();
         }, NoSuchElementException.class, description);
     }

     /**
      * Tests the headSet() method.
      */
     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testHeadSet(String description, NavigableSet navigableSet) {
         assertThrows(
             () -> { NavigableSet ns = navigableSet.headSet(null, false); },
             NullPointerException.class,
             description + ": Must throw NullPointerException for null element");

         assertThrows(
             () -> { NavigableSet ns = navigableSet.headSet(new Object(), true); },
             ClassCastException.class,
             description + ": Must throw ClassCastException for non-Comparable element");

         NavigableSet ns = navigableSet.headSet("1", false);

         assertEmptyNavigableSet(ns, description + ": Returned value is not empty navigable set.");
     }

     /**
      * Tests that the last() method throws NoSuchElementException
      */
     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testLast(String description, NavigableSet<?> navigableSet) {
         assertThrows(() -> {
             navigableSet.last();
         }, NoSuchElementException.class, description);
     }

     /**
      * Tests that the size is 0.
      */
     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testSizeIsZero(String description, NavigableSet<?> navigableSet) {
         assertTrue(0 == navigableSet.size(), "The size of the set is not 0.");
     }

     /**
      * Tests the subSet() method.
      */
     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testSubSet(String description, NavigableSet navigableSet) {
         assertThrows(
             () -> {
                 SortedSet ss = navigableSet.subSet(null, BigInteger.TEN);
             },
             NullPointerException.class,
             description + ": Must throw NullPointerException for null element");

         assertThrows(
             () -> {
                 SortedSet ss = navigableSet.subSet(BigInteger.ZERO, null);
             },
             NullPointerException.class,
             description + ": Must throw NullPointerException for null element");

         assertThrows(
             () -> {
                 SortedSet ss = navigableSet.subSet(null, null);
             },
             NullPointerException.class,
             description + ": Must throw NullPointerException for null element");

         Object obj1 = new Object();
         Object obj2 = new Object();

         assertThrows(
             () -> {
                 SortedSet ss = navigableSet.subSet(obj1, BigInteger.TEN);
             },
             ClassCastException.class, description
             + ": Must throw ClassCastException for parameter which is not Comparable.");

         assertThrows(
             () -> {
                 SortedSet ss = navigableSet.subSet(BigInteger.ZERO, obj2);
             },
             ClassCastException.class, description
             + ": Must throw ClassCastException for parameter which is not Comparable.");

         assertThrows(
             () -> {
                 SortedSet ss = navigableSet.subSet(obj1, obj2);
             },
             ClassCastException.class, description
             + ": Must throw ClassCastException for parameter which is not Comparable.");

         // minimal range
         navigableSet.subSet(BigInteger.ZERO, false, BigInteger.ZERO, false);
         navigableSet.subSet(BigInteger.ZERO, false, BigInteger.ZERO, true);
         navigableSet.subSet(BigInteger.ZERO, true, BigInteger.ZERO, false);
         navigableSet.subSet(BigInteger.ZERO, true, BigInteger.ZERO, true);

         Object first = isDescending(navigableSet) ? BigInteger.TEN : BigInteger.ZERO;
         Object last = (BigInteger.ZERO == first) ? BigInteger.TEN : BigInteger.ZERO;

             assertThrows(
                 () -> {
                     navigableSet.subSet(last, true, first, false);
                 },
                 IllegalArgumentException.class, description
                 + ": Must throw IllegalArgumentException when fromElement is not less then then toElement.");

         navigableSet.subSet(first, true, last, false);
     }

     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testSubSetRanges(String description, NavigableSet navigableSet) {
         Object first = isDescending(navigableSet) ? BigInteger.TEN : BigInteger.ZERO;
         Object last = (BigInteger.ZERO == first) ? BigInteger.TEN : BigInteger.ZERO;

         NavigableSet subSet = navigableSet.subSet(first, true, last, true);

         // same subset
         subSet.subSet(first, true, last, true);

         // slightly smaller
         NavigableSet ns = subSet.subSet(first, false, last, false);
         // slight exapansion
         assertThrows(() -> {
             ns.subSet(first, true, last, true);
         },
             IllegalArgumentException.class,
             description + ": Expansion should not be allowed");

         // much smaller
         subSet.subSet(first, false, BigInteger.ONE, false);
     }

     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testheadSetRanges(String description, NavigableSet navigableSet) {
         NavigableSet subSet = navigableSet.headSet(BigInteger.ONE, true);

         // same subset
         subSet.headSet(BigInteger.ONE, true);

         // slightly smaller
         NavigableSet ns = subSet.headSet(BigInteger.ONE, false);

         // slight exapansion
         assertThrows(() -> {
             ns.headSet(BigInteger.ONE, true);
         },
             IllegalArgumentException.class,
             description + ": Expansion should not be allowed");

         // much smaller
         subSet.headSet(isDescending(subSet) ? BigInteger.TEN : BigInteger.ZERO, true);
     }

     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testTailSetRanges(String description, NavigableSet navigableSet) {
         NavigableSet subSet = navigableSet.tailSet(BigInteger.ONE, true);

         // same subset
         subSet.tailSet(BigInteger.ONE, true);

         // slightly smaller
         NavigableSet ns = subSet.tailSet(BigInteger.ONE, false);

         // slight exapansion
         assertThrows(() -> {
             ns.tailSet(BigInteger.ONE, true);
         },
             IllegalArgumentException.class,
             description + ": Expansion should not be allowed");

         // much smaller
         subSet.tailSet(isDescending(subSet) ? BigInteger.ZERO : BigInteger.TEN, false);
     }

     /**
      * Tests the tailSet() method.
      */
     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testTailSet(String description, NavigableSet navigableSet) {
         assertThrows(() -> {
             navigableSet.tailSet(null);
         },
             NullPointerException.class,
             description + ": Must throw NullPointerException for null element");

         assertThrows(() -> {
             navigableSet.tailSet(new Object());
         }, ClassCastException.class);

         NavigableSet ss = navigableSet.tailSet("1", true);

         assertEmptyNavigableSet(ss, description + ": Returned value is not empty navigable set.");
     }

     /**
      * Tests that the array has a size of 0.
      */
     @Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
     public void testToArray(String description, NavigableSet<?> navigableSet) {
         Object[] emptyNavigableSetArray = navigableSet.toArray();

         assertTrue(emptyNavigableSetArray.length == 0, "Returned non-empty Array.");

         emptyNavigableSetArray = new Object[20];

         Object[] result = navigableSet.toArray(emptyNavigableSetArray);

         assertSame(emptyNavigableSetArray, result);

         assertTrue(result[0] == null);
     }

     @DataProvider(name = "NavigableSet<?>", parallel = true)
     public static Iterator<Object[]> navigableSetsProvider() {
         return makeNavigableSets().iterator();
     }

     public static Collection<Object[]> makeNavigableSets() {
         return Arrays.asList(
             new Object[]{"UnmodifiableNavigableSet(TreeSet)", Collections.unmodifiableNavigableSet(new TreeSet())},
             new Object[]{"UnmodifiableNavigableSet(TreeSet.descendingSet()", Collections.unmodifiableNavigableSet(new TreeSet().descendingSet())},
             new Object[]{"UnmodifiableNavigableSet(TreeSet.descendingSet().descendingSet()", Collections.unmodifiableNavigableSet(new TreeSet().descendingSet().descendingSet())},
             new Object[]{"emptyNavigableSet()", Collections.emptyNavigableSet()},
             new Object[]{"emptyNavigableSet().descendingSet()", Collections.emptyNavigableSet().descendingSet()},
             new Object[]{"emptyNavigableSet().descendingSet().descendingSet()", Collections.emptyNavigableSet().descendingSet().descendingSet()}
         );
     }
 }
	/*
	* Copyright (c) 2011, 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
	* @bug 4533691 7129185
	* @summary Unit test for Collections.emptyNavigableSet
	* @run testng EmptyNavigableSet
	*/
	import java.math.BigInteger;
	import java.util.Arrays;
	import java.util.Collection;
	import java.util.Collections;
	import java.util.Comparator;
	import java.util.Iterator;
	import java.util.NoSuchElementException;
	import java.util.NavigableSet;
	import java.util.SortedSet;
	import java.util.TreeSet;
	import org.testng.annotations.Test;
	import org.testng.annotations.DataProvider;

	import static org.testng.Assert.fail;
	import static org.testng.Assert.assertEquals;
	import static org.testng.Assert.assertTrue;
	import static org.testng.Assert.assertFalse;
	import static org.testng.Assert.assertSame;

	public class EmptyNavigableSet {

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

	public static <T> void assertInstance(T actual, Class<? extends T> expected, String message) {
	assertTrue(expected.isInstance(actual), ((null != message) ? message : "")
	+ " " + (actual == null ? "<null>" : actual.getClass().getSimpleName()) + " != " + expected.getSimpleName() + ". ");
	}

	public static <T extends Throwable> void assertEmptyNavigableSet(Object obj) {
	assertInstance(obj, NavigableSet.class);
	assertTrue(((NavigableSet)obj).isEmpty() && (((NavigableSet)obj).size() == 0));
	}

	public static <T extends Throwable> void assertEmptyNavigableSet(Object obj, String message) {
	assertInstance(obj, NavigableSet.class, message);
	assertTrue(((NavigableSet)obj).isEmpty() && (((NavigableSet)obj).size() == 0),
	((null != message) ? message : "") + " Not empty. ");
	}

	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 result;
	try {
	thrower.run();
	fail(((null != message) ? message : "") + "Failed to throw " + throwable.getCanonicalName() + ". ");
	return;
	} catch (Throwable caught) {
	result = caught;
	}

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

	public static final boolean isDescending(SortedSet<?> set) {
	if (null == set.comparator()) {
	// natural order
	return false;
	}

	if (Collections.reverseOrder() == set.comparator()) {
	// reverse natural order.
	return true;
	}

	if (set.comparator().equals(Collections.reverseOrder(Collections.reverseOrder(set.comparator())))) {
	// it's a Collections.reverseOrder(Comparator).
	return true;
	}

	throw new IllegalStateException("can't determine ordering for " + set);
	}

	/**
	* Tests that the comparator is {@code null}.
	*/
	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testComparatorIsNull(String description, NavigableSet<?> navigableSet) {
	Comparator comparator = navigableSet.comparator();

	assertTrue(comparator == null \|\| comparator == Collections.reverseOrder(), description + ": Comparator (" + comparator + ") is not null.");
	}

	/**
	* Tests that contains requires Comparable
	*/
	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testContainsRequiresComparable(String description, NavigableSet<?> navigableSet) {
	assertThrows(() -> {
	navigableSet.contains(new Object());
	},
	ClassCastException.class,
	description + ": Compareable should be required");
	}

	/**
	* Tests that the contains method returns {@code false}.
	*/
	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testContains(String description, NavigableSet<?> navigableSet) {
	assertFalse(navigableSet.contains(new Integer(1)),
	description + ": Should not contain any elements.");
	}

	/**
	* Tests that the containsAll method returns {@code false}.
	*/
	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testContainsAll(String description, NavigableSet<?> navigableSet) {
	TreeSet treeSet = new TreeSet();
	treeSet.add("1");
	treeSet.add("2");
	treeSet.add("3");

	assertFalse(navigableSet.containsAll(treeSet), "Should not contain any elements.");
	}

	/**
	* Tests that the iterator is empty.
	*/
	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testEmptyIterator(String description, NavigableSet<?> navigableSet) {
	Iterator emptyIterator = navigableSet.iterator();

	assertFalse((emptyIterator != null) && (emptyIterator.hasNext()),
	"The iterator is not empty.");
	}

	/**
	* Tests that the set is empty.
	*/
	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testIsEmpty(String description, NavigableSet<?> navigableSet) {
	assertTrue(navigableSet.isEmpty(), "The set is not empty.");
	}

	/**
	* Tests that the first() method throws NoSuchElementException
	*/
	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testFirst(String description, NavigableSet<?> navigableSet) {
	assertThrows(() -> {
	navigableSet.first();
	}, NoSuchElementException.class, description);
	}

	/**
	* Tests the headSet() method.
	*/
	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testHeadSet(String description, NavigableSet navigableSet) {
	assertThrows(
	() -> { NavigableSet ns = navigableSet.headSet(null, false); },
	NullPointerException.class,
	description + ": Must throw NullPointerException for null element");

	assertThrows(
	() -> { NavigableSet ns = navigableSet.headSet(new Object(), true); },
	ClassCastException.class,
	description + ": Must throw ClassCastException for non-Comparable element");

	NavigableSet ns = navigableSet.headSet("1", false);

	assertEmptyNavigableSet(ns, description + ": Returned value is not empty navigable set.");
	}

	/**
	* Tests that the last() method throws NoSuchElementException
	*/
	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testLast(String description, NavigableSet<?> navigableSet) {
	assertThrows(() -> {
	navigableSet.last();
	}, NoSuchElementException.class, description);
	}

	/**
	* Tests that the size is 0.
	*/
	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testSizeIsZero(String description, NavigableSet<?> navigableSet) {
	assertTrue(0 == navigableSet.size(), "The size of the set is not 0.");
	}

	/**
	* Tests the subSet() method.
	*/
	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testSubSet(String description, NavigableSet navigableSet) {
	assertThrows(
	() -> {
	SortedSet ss = navigableSet.subSet(null, BigInteger.TEN);
	},
	NullPointerException.class,
	description + ": Must throw NullPointerException for null element");

	assertThrows(
	() -> {
	SortedSet ss = navigableSet.subSet(BigInteger.ZERO, null);
	},
	NullPointerException.class,
	description + ": Must throw NullPointerException for null element");

	assertThrows(
	() -> {
	SortedSet ss = navigableSet.subSet(null, null);
	},
	NullPointerException.class,
	description + ": Must throw NullPointerException for null element");

	Object obj1 = new Object();
	Object obj2 = new Object();

	assertThrows(
	() -> {
	SortedSet ss = navigableSet.subSet(obj1, BigInteger.TEN);
	},
	ClassCastException.class, description
	+ ": Must throw ClassCastException for parameter which is not Comparable.");

	assertThrows(
	() -> {
	SortedSet ss = navigableSet.subSet(BigInteger.ZERO, obj2);
	},
	ClassCastException.class, description
	+ ": Must throw ClassCastException for parameter which is not Comparable.");

	assertThrows(
	() -> {
	SortedSet ss = navigableSet.subSet(obj1, obj2);
	},
	ClassCastException.class, description
	+ ": Must throw ClassCastException for parameter which is not Comparable.");

	// minimal range
	navigableSet.subSet(BigInteger.ZERO, false, BigInteger.ZERO, false);
	navigableSet.subSet(BigInteger.ZERO, false, BigInteger.ZERO, true);
	navigableSet.subSet(BigInteger.ZERO, true, BigInteger.ZERO, false);
	navigableSet.subSet(BigInteger.ZERO, true, BigInteger.ZERO, true);

	Object first = isDescending(navigableSet) ? BigInteger.TEN : BigInteger.ZERO;
	Object last = (BigInteger.ZERO == first) ? BigInteger.TEN : BigInteger.ZERO;

	assertThrows(
	() -> {
	navigableSet.subSet(last, true, first, false);
	},
	IllegalArgumentException.class, description
	+ ": Must throw IllegalArgumentException when fromElement is not less then then toElement.");

	navigableSet.subSet(first, true, last, false);
	}

	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testSubSetRanges(String description, NavigableSet navigableSet) {
	Object first = isDescending(navigableSet) ? BigInteger.TEN : BigInteger.ZERO;
	Object last = (BigInteger.ZERO == first) ? BigInteger.TEN : BigInteger.ZERO;

	NavigableSet subSet = navigableSet.subSet(first, true, last, true);

	// same subset
	subSet.subSet(first, true, last, true);

	// slightly smaller
	NavigableSet ns = subSet.subSet(first, false, last, false);
	// slight exapansion
	assertThrows(() -> {
	ns.subSet(first, true, last, true);
	},
	IllegalArgumentException.class,
	description + ": Expansion should not be allowed");

	// much smaller
	subSet.subSet(first, false, BigInteger.ONE, false);
	}

	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testheadSetRanges(String description, NavigableSet navigableSet) {
	NavigableSet subSet = navigableSet.headSet(BigInteger.ONE, true);

	// same subset
	subSet.headSet(BigInteger.ONE, true);

	// slightly smaller
	NavigableSet ns = subSet.headSet(BigInteger.ONE, false);

	// slight exapansion
	assertThrows(() -> {
	ns.headSet(BigInteger.ONE, true);
	},
	IllegalArgumentException.class,
	description + ": Expansion should not be allowed");

	// much smaller
	subSet.headSet(isDescending(subSet) ? BigInteger.TEN : BigInteger.ZERO, true);
	}

	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testTailSetRanges(String description, NavigableSet navigableSet) {
	NavigableSet subSet = navigableSet.tailSet(BigInteger.ONE, true);

	// same subset
	subSet.tailSet(BigInteger.ONE, true);

	// slightly smaller
	NavigableSet ns = subSet.tailSet(BigInteger.ONE, false);

	// slight exapansion
	assertThrows(() -> {
	ns.tailSet(BigInteger.ONE, true);
	},
	IllegalArgumentException.class,
	description + ": Expansion should not be allowed");

	// much smaller
	subSet.tailSet(isDescending(subSet) ? BigInteger.ZERO : BigInteger.TEN, false);
	}

	/**
	* Tests the tailSet() method.
	*/
	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testTailSet(String description, NavigableSet navigableSet) {
	assertThrows(() -> {
	navigableSet.tailSet(null);
	},
	NullPointerException.class,
	description + ": Must throw NullPointerException for null element");

	assertThrows(() -> {
	navigableSet.tailSet(new Object());
	}, ClassCastException.class);

	NavigableSet ss = navigableSet.tailSet("1", true);

	assertEmptyNavigableSet(ss, description + ": Returned value is not empty navigable set.");
	}

	/**
	* Tests that the array has a size of 0.
	*/
	@Test(dataProvider = "NavigableSet<?>", dataProviderClass = EmptyNavigableSet.class)
	public void testToArray(String description, NavigableSet<?> navigableSet) {
	Object[] emptyNavigableSetArray = navigableSet.toArray();

	assertTrue(emptyNavigableSetArray.length == 0, "Returned non-empty Array.");

	emptyNavigableSetArray = new Object[20];

	Object[] result = navigableSet.toArray(emptyNavigableSetArray);

	assertSame(emptyNavigableSetArray, result);

	assertTrue(result[0] == null);
	}

	@DataProvider(name = "NavigableSet<?>", parallel = true)
	public static Iterator<Object[]> navigableSetsProvider() {
	return makeNavigableSets().iterator();
	}

	public static Collection<Object[]> makeNavigableSets() {
	return Arrays.asList(
	new Object[]{"UnmodifiableNavigableSet(TreeSet)", Collections.unmodifiableNavigableSet(new TreeSet())},
	new Object[]{"UnmodifiableNavigableSet(TreeSet.descendingSet()", Collections.unmodifiableNavigableSet(new TreeSet().descendingSet())},
	new Object[]{"UnmodifiableNavigableSet(TreeSet.descendingSet().descendingSet()", Collections.unmodifiableNavigableSet(new TreeSet().descendingSet().descendingSet())},
	new Object[]{"emptyNavigableSet()", Collections.emptyNavigableSet()},
	new Object[]{"emptyNavigableSet().descendingSet()", Collections.emptyNavigableSet().descendingSet()},
	new Object[]{"emptyNavigableSet().descendingSet().descendingSet()", Collections.emptyNavigableSet().descendingSet().descendingSet()}
	);
	}
	}