wamblee.org Git - utils/blob - support/general/src/test/java/org/wamblee/cache/ComputedValueTest.java

   1 /*
   2  * Copyright 2005-2010 the original author or 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 package org.wamblee.cache;
  17
  18 import static org.mockito.Mockito.*;
  19
  20 import java.util.ArrayList;
  21 import java.util.List;
  22
  23 import junit.framework.TestCase;
  24
  25 import org.mockito.invocation.InvocationOnMock;
  26 import org.mockito.stubbing.Answer;
  27 import org.wamblee.cache.ComputedValue.Computation;
  28
  29 public class ComputedValueTest extends TestCase {
  30
  31     private Computation<Integer> computation;
  32     private ComputedValue<Integer> guard;
  33
  34
  35     @Override
  36     protected void setUp() throws Exception {
  37         computation = mock(Computation.class);
  38     }
  39
  40     public void testComputeOutOfDate() {
  41         initGuard();
  42     }
  43
  44     private void initGuard() {
  45         guard = new ComputedValue<Integer>(this, computation);
  46
  47         assertNull(guard.getCached());
  48
  49         when(computation.isOutOfDate()).thenReturn(true);
  50         when(computation.compute()).thenReturn(10);
  51
  52         int value = guard.get();
  53         assertEquals(10, value);
  54         verify(computation).compute();
  55         reset(computation);
  56     }
  57
  58     public void testGetCached() {
  59         initGuard();
  60         assertEquals(10, (int)guard.getCached());
  61         verifyNoMoreInteractions(computation);
  62     }
  63
  64     public void testNoComputationWhenNotOutOfDate() {
  65         initGuard();
  66         when(computation.isOutOfDate()).thenReturn(false);
  67         assertEquals(10, (int) guard.get());
  68         verify(computation, never()).compute();
  69     }
  70
  71     public void testOnlyOneConcurrentComputation() throws Exception {
  72         initGuard();
  73         final int computeTime = 500;
  74         when(computation.isOutOfDate()).thenReturn(true);
  75         when(computation.compute()).thenAnswer(new Answer<Integer>() {
  76             @Override
  77             public Integer answer(InvocationOnMock aInvocation)
  78                 throws Throwable {
  79                 Thread.sleep(computeTime);
  80                 return 100;
  81             }
  82         });
  83
  84         final List<Integer> results = new ArrayList<Integer>();
  85
  86         Runnable task = new Runnable() {
  87             @Override
  88             public void run() {
  89                 int res = guard.get();
  90                 results.add(res);
  91             }
  92         };
  93
  94         // concurrent computation in two threads.
  95         Thread t1 = new Thread(task);
  96         Thread t2 = new Thread(task);
  97         t1.start();
  98         Thread.sleep(computeTime / 2);
  99         // second task will return old value 10 because first one is still busy.
 100         t2.start();
 101         t1.join();
 102         t2.join();
 103         assertEquals(2, results.size());
 104         assertEquals(10, (int) results.get(0));
 105         assertEquals(100, (int) results.get(1));
 106         verify(computation, times(2)).isOutOfDate();
 107     }
 108
 109     public void testExceptionWhileComputing() {
 110         initGuard();
 111         when(computation.isOutOfDate()).thenReturn(true);
 112         when(computation.compute()).thenThrow(new RuntimeException("xx"));
 113         try {
 114             guard.get();
 115             fail();
 116         } catch (RuntimeException e) {
 117             assertEquals("xx", e.getMessage());
 118         }
 119     }
 120
 121     public void testExceptionWhileCheckingOutOfDate() {
 122         initGuard();
 123         when(computation.isOutOfDate()).thenThrow(new RuntimeException("xx"));
 124         try {
 125             guard.get();
 126             fail();
 127         } catch (RuntimeException e) {
 128             assertEquals("xx", e.getMessage());
 129         }
 130     }
 131 }