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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.tv.testing;
     18 
     19 import junit.framework.Assert;
     20 
     21 import java.util.ArrayList;
     22 import java.util.Arrays;
     23 import java.util.Collection;
     24 import java.util.List;
     25 
     26 /**
     27  * Tester for {@link java.lang.Comparable}s.
     28  *
     29  * <p>
     30  * To use, create a new {@link ComparableTester} and add comparable groups
     31  * where each group contains objects that are
     32  * {@link java.util.Comparator#compare(Object, Object)} == 0 to each other.
     33  * Groups are added in order asserting that all earlier groups have compare < 0
     34  * for all later groups.
     35  *
     36  * <pre>{@code
     37  * new ComparableTester<String>()
     38  *     .addEquivalentGroup("Hello", "HELLO")
     39  *     .addEquivalentGroup("World", "wORLD")
     40  *     .addEquivalentGroup("ZEBRA")
     41  *     .test();
     42  * }
     43  * </pre>
     44  *
     45  * @param <T> the type of objects to compare.
     46  */
     47 public class ComparableTester<T extends Comparable<T>> {
     48 
     49     private final List<List<T>> listOfGroups = new ArrayList<>();
     50 
     51     @SafeVarargs
     52     public final ComparableTester<T> addEquivalentGroup(T... items) {
     53         listOfGroups.add(Arrays.asList(items));
     54         return this;
     55     }
     56 
     57     public void test() {
     58         for (int i = 0; i < listOfGroups.size(); i++) {
     59             List<T> currentGroup = listOfGroups.get(i);
     60             for (int j = 0; j < i; j++) {
     61                 List<T> lhs = listOfGroups.get(j);
     62                 assertOrder(i, j, lhs, currentGroup);
     63             }
     64             assertZero(currentGroup);
     65             for (int j = i + 1; j < listOfGroups.size(); j++) {
     66                 List<T> rhs = listOfGroups.get(j);
     67                 assertOrder(i, j, currentGroup, rhs);
     68             }
     69         }
     70     }
     71 
     72     private void assertOrder(int less, int more, List<T> lessGroup, List<T> moreGroup) {
     73         assertLess(less, more, lessGroup, moreGroup);
     74         assertMore(more, less, moreGroup, lessGroup);
     75     }
     76 
     77     private void assertLess(int left, int right, Collection<T> leftGroup,
     78             Collection<T> rightGroup) {
     79         int leftSub = 0;
     80         for (T leftItem : leftGroup) {
     81             int rightSub = 0;
     82             String leftName = "Item[" + left + "," + (leftSub++) + "]";
     83             for (T rightItem : rightGroup) {
     84                 String rightName = "Item[" + right + "," + (rightSub++) + "]";
     85                 Assert.assertEquals(
     86                         leftName + " " + leftItem + " compareTo  " + rightName + " " + rightItem
     87                                 + " is <0", true, leftItem.compareTo(rightItem) < 0);
     88             }
     89         }
     90     }
     91 
     92     private void assertMore(int left, int right, Collection<T> leftGroup,
     93             Collection<T> rightGroup) {
     94         int leftSub = 0;
     95         for (T leftItem : leftGroup) {
     96             int rightSub = 0;
     97             String leftName = "Item[" + left + "," + (leftSub++) + "]";
     98             for (T rightItem : rightGroup) {
     99                 String rightName = "Item[" + right + "," + (rightSub++) + "]";
    100                 Assert.assertEquals(
    101                         leftName + " " + leftItem + " compareTo  " + rightName + " " + rightItem
    102                                 + " is >0", true, leftItem.compareTo(rightItem) > 0);
    103             }
    104         }
    105     }
    106 
    107     private void assertZero(Collection<T> group) {
    108         // Test everything against everything in both directions, including against itself.
    109         for (T lhs : group) {
    110             for (T rhs : group) {
    111                 Assert.assertEquals(lhs + " compareTo " + rhs, 0, lhs.compareTo(rhs));
    112             }
    113         }
    114     }
    115 }
    116