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