--- jsr166/src/test/tck/ConcurrentHashMapTest.java 2003/09/07 20:39:11 1.2 +++ jsr166/src/test/tck/ConcurrentHashMapTest.java 2013/07/14 21:41:06 1.33 @@ -1,166 +1,325 @@ /* - * Written by members of JCP JSR-166 Expert Group and released to the - * public domain. Use, modify, and redistribute this code in any way - * without acknowledgement. Other contributors include Andrew Wright, - * Jeffrey Hayes, Pat Fischer, Mike Judd. + * Written by Doug Lea with assistance from members of JCP JSR-166 + * Expert Group and released to the public domain, as explained at + * http://creativecommons.org/publicdomain/zero/1.0/ + * Other contributors include Andrew Wright, Jeffrey Hayes, + * Pat Fisher, Mike Judd. */ import junit.framework.*; import java.util.*; -import java.util.concurrent.*; -import java.util.Enumeration; -import java.io.*; +import java.util.concurrent.ConcurrentHashMap; -public class ConcurrentHashMapTest extends TestCase{ +public class ConcurrentHashMapTest extends JSR166TestCase { public static void main(String[] args) { - junit.textui.TestRunner.run (suite()); + junit.textui.TestRunner.run(suite()); } public static Test suite() { - return new TestSuite(ConcurrentHashMapTest.class); + return new TestSuite(ConcurrentHashMapTest.class); } - static final Integer one = new Integer(1); - static final Integer two = new Integer(2); - static final Integer three = new Integer(3); - static final Integer four = new Integer(4); - static final Integer five = new Integer(5); - - private static ConcurrentHashMap map5() { - ConcurrentHashMap map = new ConcurrentHashMap(5); + /** + * Returns a new map from Integers 1-5 to Strings "A"-"E". + */ + private static ConcurrentHashMap map5() { + ConcurrentHashMap map = new ConcurrentHashMap(5); assertTrue(map.isEmpty()); - map.put(one, "A"); - map.put(two, "B"); - map.put(three, "C"); - map.put(four, "D"); - map.put(five, "E"); + map.put(one, "A"); + map.put(two, "B"); + map.put(three, "C"); + map.put(four, "D"); + map.put(five, "E"); assertFalse(map.isEmpty()); assertEquals(5, map.size()); - return map; + return map; + } + + /** Re-implement Integer.compare for old java versions */ + static int compare(int x, int y) { return x < y ? -1 : x > y ? 1 : 0; } + + // classes for testing Comparable fallbacks + static class BI implements Comparable { + private final int value; + BI(int value) { this.value = value; } + public int compareTo(BI other) { + return compare(value, other.value); + } + public boolean equals(Object x) { + return (x instanceof BI) && ((BI)x).value == value; + } + public int hashCode() { return 42; } + } + static class CI extends BI { CI(int value) { super(value); } } + static class DI extends BI { DI(int value) { super(value); } } + + static class BS implements Comparable { + private final String value; + BS(String value) { this.value = value; } + public int compareTo(BS other) { + return value.compareTo(other.value); + } + public boolean equals(Object x) { + return (x instanceof BS) && value.equals(((BS)x).value); + } + public int hashCode() { return 42; } + } + + static class LexicographicList> extends ArrayList + implements Comparable> { + LexicographicList(Collection c) { super(c); } + LexicographicList(E e) { super(Collections.singleton(e)); } + public int compareTo(LexicographicList other) { + int common = Math.min(size(), other.size()); + int r = 0; + for (int i = 0; i < common; i++) { + if ((r = get(i).compareTo(other.get(i))) != 0) + break; + } + if (r == 0) + r = compare(size(), other.size()); + return r; + } + private static final long serialVersionUID = 0; } /** - * Test to verify clear correctly removes all key-element pairs from the map + * Inserted elements that are subclasses of the same Comparable + * class are found. */ - public void testClear(){ - ConcurrentHashMap map = map5(); - map.clear(); - assertEquals(map.size(), 0); + public void testComparableFamily() { + ConcurrentHashMap m = + new ConcurrentHashMap(); + for (int i = 0; i < 1000; i++) { + assertTrue(m.put(new CI(i), true) == null); + } + for (int i = 0; i < 1000; i++) { + assertTrue(m.containsKey(new CI(i))); + assertTrue(m.containsKey(new DI(i))); + } } /** - * Test to verify contains gives the appropriate value + * Elements of classes with erased generic type parameters based + * on Comparable can be inserted and found. */ - public void testContains(){ - ConcurrentHashMap map = map5(); - assertTrue(map.contains("A")); - assertFalse(map.contains("Z")); + public void testGenericComparable() { + ConcurrentHashMap m = + new ConcurrentHashMap(); + for (int i = 0; i < 1000; i++) { + BI bi = new BI(i); + BS bs = new BS(String.valueOf(i)); + LexicographicList bis = new LexicographicList(bi); + LexicographicList bss = new LexicographicList(bs); + assertTrue(m.putIfAbsent(bis, true) == null); + assertTrue(m.containsKey(bis)); + if (m.putIfAbsent(bss, true) == null) + assertTrue(m.containsKey(bss)); + assertTrue(m.containsKey(bis)); + } + for (int i = 0; i < 1000; i++) { + assertTrue(m.containsKey(new ArrayList(Collections.singleton(new BI(i))))); + } } - + /** - * Test to verify containsKey gives the appropriate value + * Elements of non-comparable classes equal to those of classes + * with erased generic type parameters based on Comparable can be + * inserted and found. + */ + public void testGenericComparable2() { + ConcurrentHashMap m = + new ConcurrentHashMap(); + for (int i = 0; i < 1000; i++) { + m.put(new ArrayList(Collections.singleton(new BI(i))), true); + } + + for (int i = 0; i < 1000; i++) { + LexicographicList bis = new LexicographicList(new BI(i)); + assertTrue(m.containsKey(bis)); + } + } + + /** + * clear removes all pairs */ - public void testContainsKey(){ + public void testClear() { ConcurrentHashMap map = map5(); - assertTrue(map.containsKey(one)); - assertFalse(map.containsKey(new Integer(100))); + map.clear(); + assertEquals(0, map.size()); } /** - * Identical to normal contains + * Maps with same contents are equal */ - public void testContainsValue(){ + public void testEquals() { + ConcurrentHashMap map1 = map5(); + ConcurrentHashMap map2 = map5(); + assertEquals(map1, map2); + assertEquals(map2, map1); + map1.clear(); + assertFalse(map1.equals(map2)); + assertFalse(map2.equals(map1)); + } + + /** + * contains returns true for contained value + */ + public void testContains() { ConcurrentHashMap map = map5(); - assertTrue(map.contains("A")); + assertTrue(map.contains("A")); assertFalse(map.contains("Z")); } /** - * tes to verify enumeration returns an enumeration containing the correct elements + * containsKey returns true for contained key + */ + public void testContainsKey() { + ConcurrentHashMap map = map5(); + assertTrue(map.containsKey(one)); + assertFalse(map.containsKey(zero)); + } + + /** + * containsValue returns true for held values */ - public void testEnumeration(){ + public void testContainsValue() { ConcurrentHashMap map = map5(); - Enumeration e = map.elements(); - int count = 0; - while(e.hasMoreElements()){ - count++; - e.nextElement(); - } - assertEquals(5, count); + assertTrue(map.containsValue("A")); + assertFalse(map.containsValue("Z")); } /** - * Test to verify get returns the correct element at the given index + * enumeration returns an enumeration containing the correct + * elements */ - public void testGet(){ + public void testEnumeration() { ConcurrentHashMap map = map5(); - assertEquals("A", (String)map.get(one)); + Enumeration e = map.elements(); + int count = 0; + while (e.hasMoreElements()) { + count++; + e.nextElement(); + } + assertEquals(5, count); } /** - * Test to verify get on a nonexistant key returns null + * get returns the correct element at the given key, + * or null if not present */ - public void testGet2(){ + public void testGet() { + ConcurrentHashMap map = map5(); + assertEquals("A", (String)map.get(one)); ConcurrentHashMap empty = new ConcurrentHashMap(); - assertNull(empty.get("anything")); + assertNull(map.get("anything")); } /** - * Simple test to verify isEmpty returns the correct value + * isEmpty is true of empty map and false for non-empty */ - public void testIsEmpty(){ + public void testIsEmpty() { ConcurrentHashMap empty = new ConcurrentHashMap(); ConcurrentHashMap map = map5(); - assertTrue(empty.isEmpty()); + assertTrue(empty.isEmpty()); assertFalse(map.isEmpty()); } /** - * Test to verify keys returns an enumeration containing all the keys from the map + * keys returns an enumeration containing all the keys from the map + */ + public void testKeys() { + ConcurrentHashMap map = map5(); + Enumeration e = map.keys(); + int count = 0; + while (e.hasMoreElements()) { + count++; + e.nextElement(); + } + assertEquals(5, count); + } + + /** + * keySet returns a Set containing all the keys */ - public void testKeys(){ + public void testKeySet() { ConcurrentHashMap map = map5(); - Enumeration e = map.keys(); - int count = 0; - while(e.hasMoreElements()){ - count++; - e.nextElement(); - } - assertEquals(5, count); + Set s = map.keySet(); + assertEquals(5, s.size()); + assertTrue(s.contains(one)); + assertTrue(s.contains(two)); + assertTrue(s.contains(three)); + assertTrue(s.contains(four)); + assertTrue(s.contains(five)); } /** - * Test to verify keySet returns a Set containing all the keys + * keySet.toArray returns contains all keys */ - public void testKeySet(){ + public void testKeySetToArray() { ConcurrentHashMap map = map5(); - Set s = map.keySet(); - assertEquals(5, s.size()); - assertTrue(s.contains(one)); - assertTrue(s.contains(two)); - assertTrue(s.contains(three)); - assertTrue(s.contains(four)); - assertTrue(s.contains(five)); + Set s = map.keySet(); + Object[] ar = s.toArray(); + assertTrue(s.containsAll(Arrays.asList(ar))); + assertEquals(5, ar.length); + ar[0] = m10; + assertFalse(s.containsAll(Arrays.asList(ar))); } - public void testValues(){ + /** + * Values.toArray contains all values + */ + public void testValuesToArray() { ConcurrentHashMap map = map5(); - Collection s = map.values(); - assertEquals(5, s.size()); - assertTrue(s.contains("A")); - assertTrue(s.contains("B")); - assertTrue(s.contains("C")); - assertTrue(s.contains("D")); - assertTrue(s.contains("E")); + Collection v = map.values(); + Object[] ar = v.toArray(); + ArrayList s = new ArrayList(Arrays.asList(ar)); + assertEquals(5, ar.length); + assertTrue(s.contains("A")); + assertTrue(s.contains("B")); + assertTrue(s.contains("C")); + assertTrue(s.contains("D")); + assertTrue(s.contains("E")); } - public void testEntrySet(){ + /** + * entrySet.toArray contains all entries + */ + public void testEntrySetToArray() { ConcurrentHashMap map = map5(); - Set s = map.entrySet(); - assertEquals(5, s.size()); + Set s = map.entrySet(); + Object[] ar = s.toArray(); + assertEquals(5, ar.length); + for (int i = 0; i < 5; ++i) { + assertTrue(map.containsKey(((Map.Entry)(ar[i])).getKey())); + assertTrue(map.containsValue(((Map.Entry)(ar[i])).getValue())); + } + } + + /** + * values collection contains all values + */ + public void testValues() { + ConcurrentHashMap map = map5(); + Collection s = map.values(); + assertEquals(5, s.size()); + assertTrue(s.contains("A")); + assertTrue(s.contains("B")); + assertTrue(s.contains("C")); + assertTrue(s.contains("D")); + assertTrue(s.contains("E")); + } + + /** + * entrySet contains all pairs + */ + public void testEntrySet() { + ConcurrentHashMap map = map5(); + Set s = map.entrySet(); + assertEquals(5, s.size()); Iterator it = s.iterator(); while (it.hasNext()) { Map.Entry e = (Map.Entry) it.next(); - assertTrue( + assertTrue( (e.getKey().equals(one) && e.getValue().equals("A")) || (e.getKey().equals(two) && e.getValue().equals("B")) || (e.getKey().equals(three) && e.getValue().equals("C")) || @@ -170,202 +329,360 @@ public class ConcurrentHashMapTest exten } /** - * Test to verify putAll correctly adds all key-value pairs from the given map + * putAll adds all key-value pairs from the given map */ - public void testPutAll(){ + public void testPutAll() { ConcurrentHashMap empty = new ConcurrentHashMap(); ConcurrentHashMap map = map5(); - empty.putAll(map); - assertEquals(5, empty.size()); - assertTrue(empty.containsKey(one)); - assertTrue(empty.containsKey(two)); - assertTrue(empty.containsKey(three)); - assertTrue(empty.containsKey(four)); - assertTrue(empty.containsKey(five)); + empty.putAll(map); + assertEquals(5, empty.size()); + assertTrue(empty.containsKey(one)); + assertTrue(empty.containsKey(two)); + assertTrue(empty.containsKey(three)); + assertTrue(empty.containsKey(four)); + assertTrue(empty.containsKey(five)); } /** - * Test to verify putIfAbsent works when the given key is not present + * putIfAbsent works when the given key is not present */ - public void testPutIfAbsent(){ + public void testPutIfAbsent() { ConcurrentHashMap map = map5(); - map.putIfAbsent(new Integer(6), "Z"); - assertTrue(map.containsKey(new Integer(6))); + map.putIfAbsent(six, "Z"); + assertTrue(map.containsKey(six)); } /** - * Test to verify putIfAbsent does not add the pair if the key is already present + * putIfAbsent does not add the pair if the key is already present */ - public void testPutIfAbsent2(){ + public void testPutIfAbsent2() { ConcurrentHashMap map = map5(); assertEquals("A", map.putIfAbsent(one, "Z")); } /** - * Test to verify remove removes the correct key-value pair from the map + * replace fails when the given key is not present + */ + public void testReplace() { + ConcurrentHashMap map = map5(); + assertNull(map.replace(six, "Z")); + assertFalse(map.containsKey(six)); + } + + /** + * replace succeeds if the key is already present */ - public void testRemove(){ + public void testReplace2() { ConcurrentHashMap map = map5(); - map.remove(five); - assertEquals(4, map.size()); - assertFalse(map.containsKey(five)); + assertNotNull(map.replace(one, "Z")); + assertEquals("Z", map.get(one)); } - public void testRemove2(){ + /** + * replace value fails when the given key not mapped to expected value + */ + public void testReplaceValue() { ConcurrentHashMap map = map5(); - map.remove(five, "E"); - assertEquals(4, map.size()); - assertFalse(map.containsKey(five)); - map.remove(four, "A"); - assertEquals(4, map.size()); - assertTrue(map.containsKey(four)); + assertEquals("A", map.get(one)); + assertFalse(map.replace(one, "Z", "Z")); + assertEquals("A", map.get(one)); + } + /** + * replace value succeeds when the given key mapped to expected value + */ + public void testReplaceValue2() { + ConcurrentHashMap map = map5(); + assertEquals("A", map.get(one)); + assertTrue(map.replace(one, "A", "Z")); + assertEquals("Z", map.get(one)); } /** - * Simple test to verify size returns the correct values + * remove removes the correct key-value pair from the map */ - public void testSize(){ + public void testRemove() { + ConcurrentHashMap map = map5(); + map.remove(five); + assertEquals(4, map.size()); + assertFalse(map.containsKey(five)); + } + + /** + * remove(key,value) removes only if pair present + */ + public void testRemove2() { + ConcurrentHashMap map = map5(); + map.remove(five, "E"); + assertEquals(4, map.size()); + assertFalse(map.containsKey(five)); + map.remove(four, "A"); + assertEquals(4, map.size()); + assertTrue(map.containsKey(four)); + } + + /** + * size returns the correct values + */ + public void testSize() { ConcurrentHashMap map = map5(); ConcurrentHashMap empty = new ConcurrentHashMap(); - assertEquals(0, empty.size()); - assertEquals(5, map.size()); + assertEquals(0, empty.size()); + assertEquals(5, map.size()); } - public void testToString(){ + /** + * toString contains toString of elements + */ + public void testToString() { ConcurrentHashMap map = map5(); String s = map.toString(); for (int i = 1; i <= 5; ++i) { - assertTrue(s.indexOf(String.valueOf(i)) >= 0); + assertTrue(s.contains(String.valueOf(i))); } - } + } // Exception tests - - public void testConstructor1(){ - try{ + + /** + * Cannot create with negative capacity + */ + public void testConstructor1() { + try { new ConcurrentHashMap(-1,0,1); - fail("ConcurrentHashMap(int, float, int) should throw Illegal Argument Exception"); - }catch(IllegalArgumentException e){} + shouldThrow(); + } catch (IllegalArgumentException success) {} } - public void testConstructor2(){ - try{ + /** + * Cannot create with negative concurrency level + */ + public void testConstructor2() { + try { new ConcurrentHashMap(1,0,-1); - fail("ConcurrentHashMap(int, float, int) should throw Illegal Argument Exception"); - }catch(IllegalArgumentException e){} + shouldThrow(); + } catch (IllegalArgumentException success) {} } - public void testConstructor3(){ - try{ + /** + * Cannot create with only negative capacity + */ + public void testConstructor3() { + try { new ConcurrentHashMap(-1); - fail("ConcurrentHashMap(int) should throw Illegal Argument Exception"); - }catch(IllegalArgumentException e){} + shouldThrow(); + } catch (IllegalArgumentException success) {} } - public void testGet_NullPointerException(){ - try{ + /** + * get(null) throws NPE + */ + public void testGet_NullPointerException() { + try { ConcurrentHashMap c = new ConcurrentHashMap(5); c.get(null); - fail("ConcurrentHashMap - Object get(Object) should throw Null Pointer exception"); - }catch(NullPointerException e){} + shouldThrow(); + } catch (NullPointerException success) {} } - public void testContainsKey_NullPointerException(){ - try{ + /** + * containsKey(null) throws NPE + */ + public void testContainsKey_NullPointerException() { + try { ConcurrentHashMap c = new ConcurrentHashMap(5); c.containsKey(null); - fail("ConcurrenthashMap - boolean containsKey(Object) should throw Null Pointer exception"); - }catch(NullPointerException e){} + shouldThrow(); + } catch (NullPointerException success) {} } - public void testContainsValue_NullPointerException(){ - try{ + /** + * containsValue(null) throws NPE + */ + public void testContainsValue_NullPointerException() { + try { ConcurrentHashMap c = new ConcurrentHashMap(5); c.containsValue(null); - fail("ConcurrentHashMap - boolean containsValue(Object) should throw Null Pointer exception"); - }catch(NullPointerException e){} + shouldThrow(); + } catch (NullPointerException success) {} } - public void testContains_NullPointerException(){ - try{ + /** + * contains(null) throws NPE + */ + public void testContains_NullPointerException() { + try { ConcurrentHashMap c = new ConcurrentHashMap(5); c.contains(null); - fail("ConcurrentHashMap - boolean contains(Object) should throw Null Pointer exception"); - }catch(NullPointerException e){} + shouldThrow(); + } catch (NullPointerException success) {} } - public void testPut1_NullPointerException(){ - try{ + /** + * put(null,x) throws NPE + */ + public void testPut1_NullPointerException() { + try { ConcurrentHashMap c = new ConcurrentHashMap(5); c.put(null, "whatever"); - fail("ConcurrentHashMap - Object put(Object, Object) should throw Null Pointer exception"); - }catch(NullPointerException e){} + shouldThrow(); + } catch (NullPointerException success) {} } - public void testPut2_NullPointerException(){ - try{ + /** + * put(x, null) throws NPE + */ + public void testPut2_NullPointerException() { + try { ConcurrentHashMap c = new ConcurrentHashMap(5); c.put("whatever", null); - fail("ConcurrentHashMap - Object put(Object, Object) should throw Null Pointer exception"); - }catch(NullPointerException e){} + shouldThrow(); + } catch (NullPointerException success) {} } - public void testPutIfAbsent1_NullPointerException(){ - try{ + /** + * putIfAbsent(null, x) throws NPE + */ + public void testPutIfAbsent1_NullPointerException() { + try { ConcurrentHashMap c = new ConcurrentHashMap(5); c.putIfAbsent(null, "whatever"); - fail("ConcurrentHashMap - Object putIfAbsent(Object, Object) should throw Null Pointer exception"); - }catch(NullPointerException e){} + shouldThrow(); + } catch (NullPointerException success) {} + } + + /** + * replace(null, x) throws NPE + */ + public void testReplace_NullPointerException() { + try { + ConcurrentHashMap c = new ConcurrentHashMap(5); + c.replace(null, "whatever"); + shouldThrow(); + } catch (NullPointerException success) {} } - public void testPutIfAbsent2_NullPointerException(){ - try{ + /** + * replace(null, x, y) throws NPE + */ + public void testReplaceValue_NullPointerException() { + try { + ConcurrentHashMap c = new ConcurrentHashMap(5); + c.replace(null, one, "whatever"); + shouldThrow(); + } catch (NullPointerException success) {} + } + + /** + * putIfAbsent(x, null) throws NPE + */ + public void testPutIfAbsent2_NullPointerException() { + try { ConcurrentHashMap c = new ConcurrentHashMap(5); c.putIfAbsent("whatever", null); - fail("COncurrentHashMap - Object putIfAbsent(Object, Object) should throw Null Pointer exception"); - }catch(NullPointerException e){} + shouldThrow(); + } catch (NullPointerException success) {} } + /** + * replace(x, null) throws NPE + */ + public void testReplace2_NullPointerException() { + try { + ConcurrentHashMap c = new ConcurrentHashMap(5); + c.replace("whatever", null); + shouldThrow(); + } catch (NullPointerException success) {} + } - public void testRemove1_NullPointerException(){ - try{ + /** + * replace(x, null, y) throws NPE + */ + public void testReplaceValue2_NullPointerException() { + try { + ConcurrentHashMap c = new ConcurrentHashMap(5); + c.replace("whatever", null, "A"); + shouldThrow(); + } catch (NullPointerException success) {} + } + + /** + * replace(x, y, null) throws NPE + */ + public void testReplaceValue3_NullPointerException() { + try { + ConcurrentHashMap c = new ConcurrentHashMap(5); + c.replace("whatever", one, null); + shouldThrow(); + } catch (NullPointerException success) {} + } + + /** + * remove(null) throws NPE + */ + public void testRemove1_NullPointerException() { + try { ConcurrentHashMap c = new ConcurrentHashMap(5); c.put("sadsdf", "asdads"); c.remove(null); - fail("ConcurrentHashMap - Object remove(Object) should throw Null pointer exceptione"); - }catch(NullPointerException e){} + shouldThrow(); + } catch (NullPointerException success) {} } - public void testRemove2_NullPointerException(){ - try{ + /** + * remove(null, x) throws NPE + */ + public void testRemove2_NullPointerException() { + try { ConcurrentHashMap c = new ConcurrentHashMap(5); c.put("sadsdf", "asdads"); c.remove(null, "whatever"); - fail("ConcurrentHashMap - Object remove(Object, Object) should throw Null pointer exceptione"); - }catch(NullPointerException e){} + shouldThrow(); + } catch (NullPointerException success) {} + } + + /** + * remove(x, null) returns false + */ + public void testRemove3() { + ConcurrentHashMap c = new ConcurrentHashMap(5); + c.put("sadsdf", "asdads"); + assertFalse(c.remove("sadsdf", null)); } - public void testSerialization() { - ConcurrentHashMap q = map5(); + /** + * A deserialized map equals original + */ + public void testSerialization() throws Exception { + Map x = map5(); + Map y = serialClone(x); - try { - ByteArrayOutputStream bout = new ByteArrayOutputStream(10000); - ObjectOutputStream out = new ObjectOutputStream(new BufferedOutputStream(bout)); - out.writeObject(q); - out.close(); + assertNotSame(x, y); + assertEquals(x.size(), y.size()); + assertEquals(x, y); + assertEquals(y, x); + } - ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray()); - ObjectInputStream in = new ObjectInputStream(new BufferedInputStream(bin)); - ConcurrentHashMap r = (ConcurrentHashMap)in.readObject(); - assertEquals(q.size(), r.size()); - assertTrue(q.equals(r)); - assertTrue(r.equals(q)); - } catch(Exception e){ - e.printStackTrace(); - fail("unexpected exception"); + /** + * SetValue of an EntrySet entry sets value in the map. + */ + public void testSetValueWriteThrough() { + // Adapted from a bug report by Eric Zoerner + ConcurrentHashMap map = new ConcurrentHashMap(2, 5.0f, 1); + assertTrue(map.isEmpty()); + for (int i = 0; i < 20; i++) + map.put(new Integer(i), new Integer(i)); + assertFalse(map.isEmpty()); + Map.Entry entry1 = (Map.Entry)map.entrySet().iterator().next(); + // Unless it happens to be first (in which case remainder of + // test is skipped), remove a possibly-colliding key from map + // which, under some implementations, may cause entry1 to be + // cloned in map + if (!entry1.getKey().equals(new Integer(16))) { + map.remove(new Integer(16)); + entry1.setValue("XYZ"); + assertTrue(map.containsValue("XYZ")); // fails if write-through broken } } - }