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      1 /*
      2  * Copyright (C) 2008 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.testers;
     18 
     19 import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_CLEAR;
     20 import static com.google.common.collect.testing.features.CollectionSize.ZERO;
     21 
     22 import com.google.common.collect.testing.AbstractCollectionTester;
     23 import com.google.common.collect.testing.features.CollectionFeature;
     24 import com.google.common.collect.testing.features.CollectionSize;
     25 
     26 /**
     27  * A generic JUnit test which tests {@code clear()} operations on a collection.
     28  * Can't be invoked directly; please see
     29  * {@link com.google.common.collect.testing.CollectionTestSuiteBuilder}.
     30  *
     31  * <p>This class is GWT compatible.
     32  *
     33  * @author George van den Driessche
     34  */
     35 public class CollectionClearTester<E> extends AbstractCollectionTester<E> {
     36   @CollectionFeature.Require(SUPPORTS_CLEAR)
     37   public void testClear() {
     38     collection.clear();
     39     assertTrue("After clear(), a collection should be empty.",
     40         collection.isEmpty());
     41   }
     42 
     43   @CollectionFeature.Require(absent = SUPPORTS_CLEAR)
     44   @CollectionSize.Require(absent = ZERO)
     45   public void testClear_unsupported() {
     46     try {
     47       collection.clear();
     48       fail("clear() should throw UnsupportedOperation if a collection does "
     49           + "not support it and is not empty.");
     50     } catch (UnsupportedOperationException expected) {
     51     }
     52     expectUnchanged();
     53   }
     54 
     55   @CollectionFeature.Require(absent = SUPPORTS_CLEAR)
     56   @CollectionSize.Require(ZERO)
     57   public void testClear_unsupportedByEmptyCollection() {
     58     try {
     59       collection.clear();
     60     } catch (UnsupportedOperationException tolerated) {
     61     }
     62     expectUnchanged();
     63   }
     64 }
     65