MapComputeIfAbsentTester.java

/*
 * Copyright (C) 2015 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.ZERO;
import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_KEYS;
import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_VALUES;
import static com.google.common.collect.testing.features.MapFeature.SUPPORTS_PUT;

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.Map;
import junit.framework.AssertionFailedError;

/**
 * A generic JUnit test which tests {@link Map#computeIfAbsent}. Can't be
 * invoked directly; please see
 * {@link com.google.common.collect.testing.MapTestSuiteBuilder}.
 * 
 * @author Louis Wasserman
 */
@GwtCompatible
public class MapComputeIfAbsentTester<K, V> extends AbstractMapTester<K, V> {

  @MapFeature.Require(SUPPORTS_PUT)
  public void testComputeIfAbsent_supportedAbsent() {
    assertEquals("computeIfAbsent(notPresent, function) should return new value",
        v3(),
        getMap().computeIfAbsent(k3(), k -> {
          assertEquals(k3(), k);
          return v3();
        }));
    expectAdded(e3());
  }
  
  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testComputeIfAbsent_supportedPresent() {
    assertEquals("computeIfAbsent(present, function) should return existing value", 
        v0(), getMap().computeIfAbsent(k0(), k -> { throw new AssertionFailedError(); }));
    expectUnchanged();
  }
  
  @MapFeature.Require(SUPPORTS_PUT)
  public void testComputeIfAbsent_functionReturnsNullNotInserted() {
    assertNull("computeIfAbsent(absent, returnsNull) should return null", 
        getMap().computeIfAbsent(k3(), k -> { 
          assertEquals(k3(), k);
          return null;
        }));
    expectUnchanged();
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)
  public void testComputeIfAbsent_nullTreatedAsAbsent() {
    initMapWithNullValue();
    assertEquals("computeIfAbsent(presentAssignedToNull, function) should return newValue",
        getValueForNullKey(),
        getMap().computeIfAbsent(getKeyForNullValue(), k -> {
          assertEquals(getKeyForNullValue(), k);
          return getValueForNullKey();
        }));
    expectReplacement(entry(getKeyForNullValue(), getValueForNullKey()));
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_KEYS})
  public void testComputeIfAbsent_nullKeySupported() {
    getMap().computeIfAbsent(null, k -> {
      assertNull(k);
      return v3();
    });
    expectAdded(entry(null, v3()));
  }

  static class ExpectedException extends RuntimeException {}

  @MapFeature.Require(SUPPORTS_PUT)
  public void testComputeIfAbsent_functionThrows() {
    try {
      getMap()
          .computeIfAbsent(
              k3(),
              k -> {
                assertEquals(k3(), k);
                throw new ExpectedException();
              });
      fail("Expected ExpectedException");
    } catch (ExpectedException expected) {
    }
    expectUnchanged();
  }

  @MapFeature.Require(absent = SUPPORTS_PUT)
  public void testComputeIfAbsent_unsupportedAbsent() {
    try {
      getMap().computeIfAbsent(k3(), k -> {
        // allowed to be called
        assertEquals(k3(), k);
        return v3();
      });
      fail("computeIfAbsent(notPresent, function) should throw");
    } catch (UnsupportedOperationException expected) {}
    expectUnchanged();
  }

  @MapFeature.Require(absent = SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testComputeIfAbsent_unsupportedPresentExistingValue() {
    try {
      assertEquals(
          "computeIfAbsent(present, returnsCurrentValue) should return present or throw",
          v0(), 
          getMap().computeIfAbsent(k0(), k -> {
            assertEquals(k0(), k);
            return v0();
          }));
    } catch (UnsupportedOperationException tolerated) {}
    expectUnchanged();
  }

  @MapFeature.Require(absent = SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testComputeIfAbsent_unsupportedPresentDifferentValue() {
    try {
      assertEquals(
          "computeIfAbsent(present, returnsDifferentValue) should return present or throw",
          v0(), getMap().computeIfAbsent(k0(), k -> {
            assertEquals(k0(), k);
            return v3();
          }));
    } catch (UnsupportedOperationException tolerated) {}
    expectUnchanged();
  }

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_KEYS)
  public void testComputeIfAbsent_nullKeyUnsupported() {
    try {
      getMap().computeIfAbsent(null, k -> {
        assertNull(k);
        return v3();
      });
      fail("computeIfAbsent(null, function) should throw");
    } catch (NullPointerException expected) {}
    expectUnchanged();
    expectNullKeyMissingWhenNullKeysUnsupported(
        "Should not contain null key after unsupported computeIfAbsent(null, function)");
  }
}