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// Copyright (C) 2017 The Android Open Source Project
//
// 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.gerrit.truth;
import static com.google.common.truth.Truth.assertAbout;
import com.google.common.truth.DefaultSubject;
import com.google.common.truth.FailureStrategy;
import com.google.common.truth.Subject;
import com.google.common.truth.SubjectFactory;
import com.google.common.truth.Truth;
import java.util.Optional;
import java.util.function.Function;
public class OptionalSubject<S extends Subject<S, ? super T>, T>
extends Subject<OptionalSubject<S, T>, Optional<T>> {
private final Function<? super T, ? extends S> valueAssertThatFunction;
public static <S extends Subject<S, ? super T>, T> OptionalSubject<S, T> assertThat(
Optional<T> optional, Function<? super T, ? extends S> elementAssertThatFunction) {
OptionalSubjectFactory<S, T> optionalSubjectFactory =
new OptionalSubjectFactory<>(elementAssertThatFunction);
return assertAbout(optionalSubjectFactory).that(optional);
}
public static OptionalSubject<DefaultSubject, ?> assertThat(Optional<?> optional) {
// Unfortunately, we need to cast to DefaultSubject as Truth.assertThat()
// only returns Subject<DefaultSubject, Object>. There shouldn't be a way
// for that method not to return a DefaultSubject because the generic type
// definitions of a Subject are quite strict.
Function<Object, DefaultSubject> valueAssertThatFunction =
value -> (DefaultSubject) Truth.assertThat(value);
return assertThat(optional, valueAssertThatFunction);
}
private OptionalSubject(
FailureStrategy failureStrategy,
Optional<T> optional,
Function<? super T, ? extends S> valueAssertThatFunction) {
super(failureStrategy, optional);
this.valueAssertThatFunction = valueAssertThatFunction;
}
public void isPresent() {
isNotNull();
Optional<T> optional = actual();
if (!optional.isPresent()) {
fail("has a value");
}
}
public void isAbsent() {
isNotNull();
Optional<T> optional = actual();
if (optional.isPresent()) {
fail("does not have a value");
}
}
public void isEmpty() {
isAbsent();
}
public S value() {
isNotNull();
isPresent();
Optional<T> optional = actual();
return valueAssertThatFunction.apply(optional.get());
}
private static class OptionalSubjectFactory<S extends Subject<S, ? super T>, T>
extends SubjectFactory<OptionalSubject<S, T>, Optional<T>> {
private Function<? super T, ? extends S> valueAssertThatFunction;
OptionalSubjectFactory(Function<? super T, ? extends S> valueAssertThatFunction) {
this.valueAssertThatFunction = valueAssertThatFunction;
}
@Override
public OptionalSubject<S, T> getSubject(FailureStrategy failureStrategy, Optional<T> optional) {
return new OptionalSubject<>(failureStrategy, optional, valueAssertThatFunction);
}
}
}
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