EquivalenceTester.of(Equivalence.equals().onResultOf(Functions.toStringFunction()))
        .addEquivalenceGroup(new IntValue(1), new IntValue(1))
        .addEquivalenceGroup(new IntValue(2))
        .test();
  }

  public void testOnResultOf_equals() {
    new EqualsTester()
        .addEqualityGroup(
            Equivalence.identity().onResultOf(Functions.toStringFunction()),

        .addEqualityGroup(
            comparator, DECREASING_INTEGER.onResultOf(StringLengthFunction.STRING_LENGTH))
        .addEqualityGroup(DECREASING_INTEGER.onResultOf(Functions.constant(1)))
        .addEqualityGroup(Ordering.natural())
        .testEquals();
    reserializeAndAssert(comparator);
    assertEquals("Ordering.natural().reverse().onResultOf(STRING_LENGTH)", comparator.toString());
  }

        .addEqualityGroup(
            comparator, DECREASING_INTEGER.onResultOf(StringLengthFunction.STRING_LENGTH))
        .addEqualityGroup(DECREASING_INTEGER.onResultOf(Functions.constant(1)))
        .addEqualityGroup(Ordering.natural())
        .testEquals();
    reserializeAndAssert(comparator);
    assertEquals("Ordering.natural().reverse().onResultOf(STRING_LENGTH)", comparator.toString());
  }

  private static final Ordering<List<Class<?>>> ORDERING_BY_CONSTRUCTOR_PARAMETER_LIST =
      Ordering.natural()
          .onResultOf((List<Class<?>> params) -> params.contains(String.class))
          .compound(
              Ordering.natural()
                  .onResultOf((List<Class<?>> params) -> params.contains(Throwable.class)))
          .reverse();

  private static final Ordering<List<Class<?>>> ORDERING_BY_CONSTRUCTOR_PARAMETER_LIST =
      Ordering.natural()
          .onResultOf((List<Class<?>> params) -> params.contains(String.class))
          .compound(
              Ordering.natural()
                  .onResultOf((List<Class<?>> params) -> params.contains(Throwable.class)))
          .reverse();

    }
    return false;
  }

  @Override
  public int hashCode() {
    return Objects.hash(function, ordering);
  }

  @Override
  public String toString() {
    return ordering + ".onResultOf(" + function + ")";
  }

  @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;

    return false;
  }

  @Override
  public int hashCode() {
    return Objects.hashCode(function, resultEquivalence);
  }

  @Override
  public String toString() {
    return resultEquivalence + ".onResultOf(" + function + ")";
  }

   * non-null objects {@code x} and {@code y}, {@code equivalence.onResultOf(function).equivalent(a,
   * b)} is true if and only if {@code equivalence.equivalent(function.apply(a), function.apply(b))}
   * is true.
   *
   * <p>For example:
   *
   * {@snippet :
   * Equivalence<Person> SAME_AGE = Equivalence.equals().onResultOf(GET_PERSON_AGE);
   * }
   *

    }
    return false;
  }

  @Override
  public int hashCode() {
    return Objects.hash(function, ordering);
  }

  @Override
  public String toString() {
    return ordering + ".onResultOf(" + function + ")";
  }

  @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;

      public Comparator<Integer> get() {
        return Ordering.natural();
      }
    },
    EXPENSIVE {
      @Override
      public Comparator<Integer> get() {
        return Ordering.natural().onResultOf(new ExpensiveComputation());
      }
    };

    public abstract Comparator<Integer> get();
  }