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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.testing;
     18 
     19 import com.google.common.annotations.GwtCompatible;
     20 
     21 import java.util.Collection;
     22 
     23 /**
     24  * Base class for collection testers.
     25  *
     26  * @param <E> the element type of the collection to be tested.
     27  *
     28  * @author Kevin Bourrillion
     29  */
     30 @GwtCompatible
     31 public abstract class AbstractCollectionTester<E>
     32     extends AbstractContainerTester<Collection<E>, E> {
     33 
     34   // TODO: replace this with an accessor.
     35   protected Collection<E> collection;
     36 
     37   @Override protected Collection<E> actualContents() {
     38     return collection;
     39   }
     40 
     41   // TODO: dispose of this once collection is encapsulated.
     42   @Override protected Collection<E> resetContainer(Collection<E> newContents) {
     43     collection = super.resetContainer(newContents);
     44     return collection;
     45   }
     46 
     47   /** @see AbstractContainerTester#resetContainer() */
     48   protected void resetCollection() {
     49     resetContainer();
     50   }
     51 
     52   /**
     53    * @return an array of the proper size with {@code null} inserted into the
     54    * middle element.
     55    */
     56   protected E[] createArrayWithNullElement() {
     57     E[] array = createSamplesArray();
     58     array[getNullLocation()] = null;
     59     return array;
     60   }
     61 
     62   protected void initCollectionWithNullElement() {
     63     E[] array = createArrayWithNullElement();
     64     resetContainer(getSubjectGenerator().create(array));
     65   }
     66 
     67   /**
     68    * Equivalent to {@link #expectMissing(Object[]) expectMissing}{@code (null)}
     69    * except that the call to {@code contains(null)} is permitted to throw a
     70    * {@code NullPointerException}.
     71    *
     72    * @param message message to use upon assertion failure
     73    */
     74   protected void expectNullMissingWhenNullUnsupported(String message) {
     75     try {
     76       assertFalse(message, actualContents().contains(null));
     77     } catch (NullPointerException tolerated) {
     78       // Tolerated
     79     }
     80   }
     81 }
     82