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      1 /*
      2  * Copyright (C) 2007 The Guava Authors
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  * http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.google.common.collect;
     18 
     19 import com.google.common.base.Function;
     20 import com.google.common.testing.NullPointerTester;
     21 
     22 import junit.framework.TestCase;
     23 
     24 import java.lang.ref.WeakReference;
     25 
     26 /**
     27  * Unit test for {@link Interners}.
     28  *
     29  * @author Kevin Bourrillion
     30  */
     31 public class InternersTest extends TestCase {
     32 
     33   public void testStrong_simplistic() {
     34     String canonical = "a";
     35     String not = new String("a");
     36 
     37     Interner<String> pool = Interners.newStrongInterner();
     38     assertSame(canonical, pool.intern(canonical));
     39     assertSame(canonical, pool.intern(not));
     40   }
     41 
     42   public void testStrong_null() {
     43     Interner<String> pool = Interners.newStrongInterner();
     44     try {
     45       pool.intern(null);
     46       fail();
     47     } catch (NullPointerException ok) {}
     48   }
     49 
     50   public void testWeak_simplistic() {
     51     String canonical = "a";
     52     String not = new String("a");
     53 
     54     Interner<String> pool = Interners.newWeakInterner();
     55     assertSame(canonical, pool.intern(canonical));
     56     assertSame(canonical, pool.intern(not));
     57   }
     58 
     59   public void testWeak_null() {
     60     Interner<String> pool = Interners.newWeakInterner();
     61     try {
     62       pool.intern(null);
     63       fail();
     64     } catch (NullPointerException ok) {}
     65   }
     66 
     67   public void testWeak_afterGC() throws InterruptedException {
     68     Integer canonical = new Integer(5);
     69     Integer not = new Integer(5);
     70 
     71     Interner<Integer> pool = Interners.newWeakInterner();
     72     assertSame(canonical, pool.intern(canonical));
     73 
     74     WeakReference<Integer> signal = new WeakReference<Integer>(canonical);
     75     canonical = null;
     76 
     77     for (int i = 0; i < 3000; i++) {
     78       System.gc();
     79       if (signal.get() == null) { // it was collected
     80         assertSame(not, pool.intern(not));
     81         return;
     82       }
     83       Thread.sleep(1);
     84     }
     85     fail("reference didn't get cleaned up");
     86   }
     87 
     88   public void testAsFunction_simplistic() {
     89     String canonical = "a";
     90     String not = new String("a");
     91 
     92     Function<String, String> internerFunction =
     93         Interners.asFunction(Interners.<String>newStrongInterner());
     94 
     95     assertSame(canonical, internerFunction.apply(canonical));
     96     assertSame(canonical, internerFunction.apply(not));
     97   }
     98 
     99   public void testNullPointerExceptions() throws Exception {
    100     new NullPointerTester().testAllPublicStaticMethods(Interners.class);
    101   }
    102 }
    103