/*
 * Copyright (C) 2008 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect.testing.testers;

import static com.google.common.collect.testing.features.CollectionSize.SEVERAL;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;
import static com.google.common.collect.testing.features.MapFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION;
import static com.google.common.collect.testing.features.MapFeature.SUPPORTS_REMOVE;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.AbstractMapTester;
import com.google.common.collect.testing.features.CollectionSize;
import com.google.common.collect.testing.features.MapFeature;

import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.Map.Entry;

/**
 * A generic JUnit test which tests {@code clear()} operations on a map.
 * Can't be invoked directly; please see
 * {@link com.google.common.collect.testing.MapTestSuiteBuilder}.
 *
 * <p>This class is GWT compatible.
 *
 * @author George van den Driessche
 * @author Chris Povirk
 */
@GwtCompatible
public class MapClearTester<K, V> extends AbstractMapTester<K, V> {
  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testClear() {
    getMap().clear();
    assertTrue("After clear(), a map should be empty.",
        getMap().isEmpty());
  }

  @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION,
      SUPPORTS_REMOVE})
  @CollectionSize.Require(SEVERAL)
  public void testClearConcurrentWithEntrySetIteration() {
    try {
      Iterator<Entry<K, V>> iterator = getMap().entrySet().iterator();
      getMap().clear();
      iterator.next();
      fail("Expected ConcurrentModificationException");
    } catch (ConcurrentModificationException expected) {
      // success
    }
  }

  @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION,
      SUPPORTS_REMOVE})
  @CollectionSize.Require(SEVERAL)
  public void testClearConcurrentWithKeySetIteration() {
    try {
      Iterator<K> iterator = getMap().keySet().iterator();
      getMap().clear();
      iterator.next();
      fail("Expected ConcurrentModificationException");
    } catch (ConcurrentModificationException expected) {
      // success
    }
  }

  @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION,
      SUPPORTS_REMOVE})
  @CollectionSize.Require(SEVERAL)
  public void testClearConcurrentWithValuesIteration() {
    try {
      Iterator<V> iterator = getMap().values().iterator();
      getMap().clear();
      iterator.next();
      fail("Expected ConcurrentModificationException");
    } catch (ConcurrentModificationException expected) {
      // success
    }
  }

  @MapFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testClear_unsupported() {
    try {
      getMap().clear();
      fail("clear() should throw UnsupportedOperation if a map does "
          + "not support it and is not empty.");
    } catch (UnsupportedOperationException expected) {
    }
    expectUnchanged();
  }

  @MapFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testClear_unsupportedByEmptyCollection() {
    try {
      getMap().clear();
    } catch (UnsupportedOperationException tolerated) {
    }
    expectUnchanged();
  }
}