/*
 * Copyright (C) 2010 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
 * diOBJECTibuted under the License is diOBJECTibuted 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.base;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.collect.ImmutableList;
import com.google.common.testing.EqualsTester;
import com.google.common.testing.EquivalenceTester;
import com.google.common.testing.SerializableTester;

import junit.framework.TestCase;

/**
 * Unit test for {@link Equivalence}.
 *
 * @author Jige Yu
 */
@GwtCompatible(emulated = true)
public class EquivalenceTest extends TestCase {

  @SuppressWarnings("unchecked") // Iterable<String>...
  public void testPairwiseEquivalent() {
    EquivalenceTester.of(Equivalences.equals().<String>pairwise())
        .addEquivalenceGroup(ImmutableList.<String>of())
        .addEquivalenceGroup(ImmutableList.of("a"))
        .addEquivalenceGroup(ImmutableList.of("b"))
        .addEquivalenceGroup(ImmutableList.of("a", "b"), ImmutableList.of("a", "b"))
        .test();
  }

  public void testPairwiseEquivalent_equals() {
    new EqualsTester()
        .addEqualityGroup(Equivalences.equals().pairwise(), Equivalences.equals().pairwise())
        .addEqualityGroup(Equivalences.identity().pairwise())
        .testEquals();
  }

  private enum LengthFunction implements Function<String, Integer> {
    INSTANCE;

    @Override public Integer apply(String input) {
      return input.length();
    }
  }

  private static final Equivalence<String> LENGTH_EQUIVALENCE = Equivalences.equals()
      .onResultOf(LengthFunction.INSTANCE);

  public void testWrap() {
    new EqualsTester()
        .addEqualityGroup(
            LENGTH_EQUIVALENCE.wrap("hello"),
            LENGTH_EQUIVALENCE.wrap("hello"),
            LENGTH_EQUIVALENCE.wrap("world"))
        .addEqualityGroup(
            LENGTH_EQUIVALENCE.wrap("hi"),
            LENGTH_EQUIVALENCE.wrap("yo"))
        .addEqualityGroup(
            LENGTH_EQUIVALENCE.wrap(null),
            LENGTH_EQUIVALENCE.wrap(null))
        .addEqualityGroup(Equivalences.equals().wrap("hello"))
        .addEqualityGroup(Equivalences.equals().wrap(null))
        .testEquals();
  }

  @GwtIncompatible("SerializableTester")
  public void testWrapSerialization() {
    SerializableTester.reserializeAndAssert(LENGTH_EQUIVALENCE.wrap("hello"));
  }

  private static class IntValue {
    private final int value;
    
    IntValue(int value) {
      this.value = value;
    }

    @Override public String toString() {
      return "value = " + value;
    }
  }
  
  public void testOnResultOf() {
    EquivalenceTester.of(Equivalences.equals().onResultOf(Functions.toStringFunction()))
        .addEquivalenceGroup(new IntValue(1), new IntValue(1))
        .addEquivalenceGroup(new IntValue(2))
        .test();
  }
  
  public void testOnResultOf_equals() {
    new EqualsTester()
        .addEqualityGroup(
            Equivalences.identity().onResultOf(Functions.toStringFunction()),
            Equivalences.identity().onResultOf(Functions.toStringFunction()))
        .addEqualityGroup(Equivalences.equals().onResultOf(Functions.toStringFunction()))
        .addEqualityGroup(Equivalences.identity().onResultOf(Functions.identity()))
        .testEquals();
  }
  
  public void testEquivalentTo() {
    Predicate<Object> equalTo1 = Equivalences.equals().equivalentTo("1");
    assertTrue(equalTo1.apply("1"));
    assertFalse(equalTo1.apply("2"));
    assertFalse(equalTo1.apply(null));
    Predicate<Object> isNull = Equivalences.equals().equivalentTo(null);
    assertFalse(isNull.apply("1"));
    assertFalse(isNull.apply("2"));
    assertTrue(isNull.apply(null));
    
    new EqualsTester()
        .addEqualityGroup(equalTo1, Equivalences.equals().equivalentTo("1"))
        .addEqualityGroup(isNull)
        .addEqualityGroup(Equivalences.identity().equivalentTo("1"))
        .testEquals();
  }
}