1 /*
   2  * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /*
  25  * @test
  26  * @bug 8009736 8010279
  27  * @run testng BasicTest
  28  */
  29 
  30 import java.util.Comparator;
  31 import java.util.function.BinaryOperator;
  32 import java.util.function.Function;
  33 import java.util.function.ToIntFunction;
  34 import org.testng.annotations.Test;
  35 
  36 
  37 import static java.util.function.BinaryOperator.minBy;
  38 import static java.util.function.BinaryOperator.maxBy;
  39 import static org.testng.Assert.assertSame;
  40 import static org.testng.Assert.fail;
  41 
  42 /**
  43  * Unit tests for helper methods in Comparators
  44  */
  45 @Test(groups = "unit")
  46 public class BasicTest {
  47 
  48     private static class People {
  49         final String firstName;
  50         final String lastName;
  51         final int age;
  52 
  53         People(String first, String last, int age) {
  54             firstName = first;
  55             lastName = last;
  56             this.age = age;
  57         }
  58 
  59         String getFirstName() { return firstName; }
  60         String getLastName() { return lastName; }
  61         int getAge() { return age; }
  62     }
  63 
  64     private final People people[] = {
  65         new People("John", "Doe", 34),
  66         new People("Mary", "Doe", 30),
  67     };
  68 
  69     public void testMaxBy() {
  70         Comparator<People> cmp = Comparator.comparing((Function<People, String>) People::getFirstName);
  71         // lesser
  72         assertSame(maxBy(cmp).apply(people[0], people[1]), people[1]);
  73         // euqal
  74         cmp = Comparator.comparing((Function<People, String>) People::getLastName);
  75         assertSame(maxBy(cmp).apply(people[0], people[1]), people[0]);
  76         // greater
  77         cmp = Comparator.comparing((ToIntFunction<People>) People::getAge);
  78         assertSame(maxBy(cmp).apply(people[0], people[1]), people[0]);
  79     }
  80 
  81     public void testLesserOf() {
  82         Comparator<People> cmp = Comparator.comparing((Function<People, String>) People::getFirstName);
  83         // lesser
  84         assertSame(minBy(cmp).apply(people[0], people[1]), people[0]);
  85         // euqal
  86         cmp = Comparator.comparing((Function<People, String>) People::getLastName);
  87         assertSame(minBy(cmp).apply(people[0], people[1]), people[0]);
  88         // greater
  89         cmp = Comparator.comparing((ToIntFunction<People>) People::getAge);
  90         assertSame(minBy(cmp).apply(people[0], people[1]), people[1]);
  91     }
  92 
  93     public void testNulls() {
  94         try {
  95             BinaryOperator<String> op = minBy(null);
  96             fail("minBy(null) should throw NPE");
  97         } catch (NullPointerException npe) {}
  98 
  99         try {
 100             BinaryOperator<String> op = maxBy(null);
 101             fail("maxBy(null) should throw NPE");
 102         } catch (NullPointerException npe) {}
 103     }
 104 }