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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 junit.framework.Assert;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
/**
* Tester for {@link java.lang.Comparable}s.
*
* <p>
* To use, create a new {@link ComparableTester} and add comparable groups
* where each group contains objects that are
* {@link java.util.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
* new ComparableTester<String>()
* .addEquivalentGroup("Hello", "HELLO")
* .addEquivalentGroup("World", "wORLD")
* .addEquivalentGroup("ZEBRA")
* .test();
* }
* </pre>
*
* @param <T> the type of objects to compare.
*/
public class ComparableTester<T extends Comparable<T>> {
private final List<List<T>> listOfGroups = new ArrayList<>();
@SafeVarargs
public final ComparableTester<T> addEquivalentGroup(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);
}
}
}
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;
String leftName = "Item[" + left + "," + (leftSub++) + "]";
for (T rightItem : rightGroup) {
String rightName = "Item[" + right + "," + (rightSub++) + "]";
Assert.assertEquals(
leftName + " " + leftItem + " compareTo " + rightName + " " + rightItem
+ " is <0", true, leftItem.compareTo(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;
String leftName = "Item[" + left + "," + (leftSub++) + "]";
for (T rightItem : rightGroup) {
String rightName = "Item[" + right + "," + (rightSub++) + "]";
Assert.assertEquals(
leftName + " " + leftItem + " compareTo " + rightName + " " + rightItem
+ " is >0", true, leftItem.compareTo(rightItem) > 0);
}
}
}
private void assertZero(Collection<T> group) {
// Test everything against everything in both directions, including against itself.
for (T lhs : group) {
for (T rhs : group) {
Assert.assertEquals(lhs + " compareTo " + rhs, 0, lhs.compareTo(rhs));
}
}
}
}
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