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/*
* Copyright (C) 2015 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.android.tv.testing;
import static junit.framework.Assert.assertEquals;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.List;
/**
* Tester for {@link Comparator} relationships between groups of T.
*
* <p>To use, create a new {@link ComparatorTester} and add comparable groups where each group
* contains objects that are {@link Comparator#compare(Object, Object)} == 0 to each other. Groups
* are added in order asserting that all earlier groups have compare < 0 for all later groups.
*
* <pre>{@code
* ComparatorTester
* .withoutEqualsTest(String.CASE_INSENSITIVE_ORDER)
* .addComparableGroup("Hello", "HELLO")
* .addComparableGroup("World", "wORLD")
* .addComparableGroup("ZEBRA")
* .test();
* }</pre>
*
* @param <T> the type of objects to compare.
*/
public class ComparatorTester<T> {
private final List<List<T>> listOfGroups = new ArrayList<>();
private final Comparator<T> comparator;
public static <T> ComparatorTester<T> withoutEqualsTest(Comparator<T> comparator) {
return new ComparatorTester<>(comparator);
}
private ComparatorTester(Comparator<T> comparator) {
this.comparator = comparator;
}
@SafeVarargs
public final ComparatorTester<T> addComparableGroup(T... items) {
listOfGroups.add(Arrays.asList(items));
return this;
}
public void test() {
for (int i = 0; i < listOfGroups.size(); i++) {
List<T> currentGroup = listOfGroups.get(i);
for (int j = 0; j < i; j++) {
List<T> lhs = listOfGroups.get(j);
assertOrder(i, j, lhs, currentGroup);
}
assertZero(currentGroup);
for (int j = i + 1; j < listOfGroups.size(); j++) {
List<T> rhs = listOfGroups.get(j);
assertOrder(i, j, currentGroup, rhs);
}
}
// TODO: also test equals
}
private void assertOrder(int less, int more, List<T> lessGroup, List<T> moreGroup) {
assertLess(less, more, lessGroup, moreGroup);
assertMore(more, less, moreGroup, lessGroup);
}
private void assertLess(
int left, int right, Collection<T> leftGroup, Collection<T> rightGroup) {
int leftSub = 0;
for (T leftItem : leftGroup) {
int rightSub = 0;
for (T rightItem : rightGroup) {
String leftName = "Item[" + left + "," + (leftSub++) + "]";
String rName = "Item[" + right + "," + (rightSub++) + "]";
assertEquals(
leftName
+ " "
+ leftItem
+ " compareTo "
+ rName
+ " "
+ rightItem
+ " is <0",
true,
comparator.compare(leftItem, rightItem) < 0);
}
}
}
private void assertMore(
int left, int right, Collection<T> leftGroup, Collection<T> rightGroup) {
int leftSub = 0;
for (T leftItem : leftGroup) {
int rightSub = 0;
for (T rightItem : rightGroup) {
String leftName = "Item[" + left + "," + (leftSub++) + "]";
String rName = "Item[" + right + "," + (rightSub++) + "]";
assertEquals(
leftName
+ " "
+ leftItem
+ " compareTo "
+ rName
+ " "
+ rightItem
+ " is >0",
true,
comparator.compare(leftItem, rightItem) > 0);
}
}
}
private void assertZero(Collection<T> group) {
// Test everything against everything in both directions, including against itself.
for (T leftItem : group) {
for (T rightItem : group) {
assertEquals(
leftItem + " compareTo " + rightItem,
0,
comparator.compare(leftItem, rightItem));
}
}
}
}
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