test/jdk/java/util/Map/InPlaceOpsCollisions.java

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  /*
!  * Copyright (c) 2013, 2016, 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.
--- 1,7 ----
  /*
!  * Copyright (c) 2013, 2019, 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.
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   * @test
   * @bug 8005698
   * @run testng/othervm -Dtest.map.collisions.shortrun=true InPlaceOpsCollisions
   * @summary Ensure overrides of in-place operations in Maps behave well with lots of collisions.
   */
+ 
+ import java.util.Arrays;
+ import java.util.Comparator;
+ import java.util.HashMap;
+ import java.util.Iterator;
+ import java.util.LinkedHashMap;
  import java.util.Map;
+ import java.util.TreeMap;
  import java.util.function.BiFunction;
  import java.util.function.Function;
  import java.util.function.Supplier;
  
+ import org.testng.annotations.DataProvider;
  import org.testng.annotations.Test;
  import static org.testng.Assert.assertTrue;
  import static org.testng.Assert.assertFalse;
  import static org.testng.Assert.assertEquals;
  import static org.testng.Assert.assertNull;
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          }
          assertEquals(map.size(), keys.length,
                  String.format("map expected size m%d != k%d", map.size(), keys.length));
      }
  
+     @Test(dataProvider = "nullValueFriendlyMaps")
+     void testPutIfAbsentOverwriteNull(String desc, Supplier<Map<Object, Object>> ms) {
+         Map<Object, Object> map = ms.get();
+         map.put("key", null);
+         assertEquals(map.size(), 1, desc + ": size != 1");
+         assertTrue(map.containsKey("key"), desc + ": does not have key");
+         assertNull(map.get("key"), desc + ": value is not null");
+         map.putIfAbsent("key", "value"); // must rewrite
+         assertEquals(map.size(), 1, desc + ": size != 1");
+         assertTrue(map.containsKey("key"), desc + ": does not have key");
+         assertEquals(map.get("key"), "value", desc + ": value is not 'value'");
+     }
+ 
      @Test(dataProvider = "mapsWithObjectsAndStrings")
      void testRemoveMapping(String desc, Supplier<Map<Object, Object>> ms, Object val) {
          Map<Object, Object> map = ms.get();
          Object[] keys = map.keySet().toArray();
          boolean removed;
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                  map.put(keys[i], val);
              }
          }
      }
  
+     @DataProvider
+     public Iterator<Object[]> nullValueFriendlyMaps() {
+         return Arrays.asList(
+                 new Object[]{"HashMap", (Supplier<Map<?, ?>>) HashMap::new},
+                 new Object[]{"LinkedHashMap", (Supplier<Map<?, ?>>) LinkedHashMap::new},
+                 new Object[]{"TreeMap", (Supplier<Map<?, ?>>) TreeMap::new},
+                 new Object[]{"TreeMap(cmp)", (Supplier<Map<?, ?>>) () -> new TreeMap<>(Comparator.reverseOrder())}
+         ).iterator();
+     }
  }