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  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
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  23 
  24 /* @test
  25  * @bug 8195649
  26  * @summary Basic functional test of Optional
  27  * @author Mike Duigou
  28  * @build ObscureException
  29  * @run testng Basic
  30  */
  31 
  32 import java.util.List;
  33 import java.util.NoSuchElementException;
  34 import java.util.Optional;
  35 import java.util.concurrent.atomic.AtomicBoolean;
  36 
  37 import static java.util.stream.Collectors.toList;
  38 
  39 import static org.testng.Assert.*;
  40 import org.testng.annotations.Test;
  41 
  42 public class Basic {
  43 
  44     /**
  45      * Checks a block of assertions over an empty Optional.
  46      */
  47     void checkEmpty(Optional<String> empty) {
  48         assertTrue(empty.equals(Optional.empty()));
  49         assertTrue(Optional.empty().equals(empty));
  50         assertFalse(empty.equals(Optional.of("unexpected")));
  51         assertFalse(Optional.of("unexpected").equals(empty));
  52         assertFalse(empty.equals("unexpected"));
  53 
  54         assertFalse(empty.isPresent());
  55         assertTrue(empty.isEmpty());
  56         assertEquals(empty.hashCode(), 0);
  57         assertEquals(empty.orElse("x"), "x");
  58         assertEquals(empty.orElseGet(() -> "y"), "y");
  59 
  60         assertThrows(NoSuchElementException.class, () -> empty.get());
  61         assertThrows(NoSuchElementException.class, () -> empty.orElseThrow());
  62         assertThrows(ObscureException.class,       () -> empty.orElseThrow(ObscureException::new));
  63 
  64         var b = new AtomicBoolean();
  65         empty.ifPresent(s -> b.set(true));
  66         assertFalse(b.get());
  67 
  68         var b1 = new AtomicBoolean(false);
  69         var b2 = new AtomicBoolean(false);
  70         empty.ifPresentOrElse(s -> b1.set(true), () -> b2.set(true));
  71         assertFalse(b1.get());
  72         assertTrue(b2.get());
  73 
  74         assertEquals(empty.toString(), "Optional.empty");
  75     }
  76 
  77     /**
  78      * Checks a block of assertions over an Optional that is expected to
  79      * have a particular value present.
  80      */
  81     void checkPresent(Optional<String> opt, String expected) {
  82         assertFalse(opt.equals(Optional.empty()));
  83         assertFalse(Optional.empty().equals(opt));
  84         assertTrue(opt.equals(Optional.of(expected)));
  85         assertTrue(Optional.of(expected).equals(opt));
  86         assertFalse(opt.equals(Optional.of("unexpected")));
  87         assertFalse(Optional.of("unexpected").equals(opt));
  88         assertFalse(opt.equals("unexpected"));
  89 
  90         assertTrue(opt.isPresent());
  91         assertFalse(opt.isEmpty());
  92         assertEquals(opt.hashCode(), expected.hashCode());
  93         assertEquals(opt.orElse("unexpected"), expected);
  94         assertEquals(opt.orElseGet(() -> "unexpected"), expected);
  95 
  96         assertEquals(opt.get(), expected);
  97         assertEquals(opt.orElseThrow(), expected);
  98         assertEquals(opt.orElseThrow(ObscureException::new), expected);
  99 
 100         var b = new AtomicBoolean(false);
 101         opt.ifPresent(s -> b.set(true));
 102         assertTrue(b.get());
 103 
 104         var b1 = new AtomicBoolean(false);
 105         var b2 = new AtomicBoolean(false);
 106         opt.ifPresentOrElse(s -> b1.set(true), () -> b2.set(true));
 107         assertTrue(b1.get());
 108         assertFalse(b2.get());
 109 
 110         assertEquals(opt.toString(), "Optional[" + expected + "]");
 111     }
 112 
 113     @Test(groups = "unit")
 114     public void testEmpty() {
 115         checkEmpty(Optional.empty());
 116     }
 117 
 118     @Test(groups = "unit")
 119     public void testOfNull() {
 120         assertThrows(NullPointerException.class, () -> Optional.of(null));
 121     }
 122 
 123     @Test(groups = "unit")
 124     public void testOfPresent() {
 125         checkPresent(Optional.of("xyzzy"), "xyzzy");
 126     }
 127 
 128     @Test(groups = "unit")
 129     public void testOfNullableNull() {
 130         checkEmpty(Optional.ofNullable(null));
 131     }
 132 
 133     @Test(groups = "unit")
 134     public void testOfNullablePresent() {
 135         checkPresent(Optional.ofNullable("xyzzy"), "xyzzy");
 136     }
 137 
 138     @Test(groups = "unit")
 139     public void testFilterEmpty() {
 140         checkEmpty(Optional.<String>empty().filter(s -> { fail(); return true; }));
 141     }
 142 
 143     @Test(groups = "unit")
 144     public void testFilterFalse() {
 145         checkEmpty(Optional.of("xyzzy").filter(s -> s.equals("plugh")));
 146     }
 147 
 148     @Test(groups = "unit")
 149     public void testFilterTrue() {
 150         checkPresent(Optional.of("xyzzy").filter(s -> s.equals("xyzzy")), "xyzzy");
 151     }
 152 
 153     @Test(groups = "unit")
 154     public void testMapEmpty() {
 155         checkEmpty(Optional.empty().map(s -> { fail(); return ""; }));
 156     }
 157 
 158     @Test(groups = "unit")
 159     public void testMapPresent() {
 160         checkPresent(Optional.of("xyzzy").map(s -> s.replace("xyzzy", "plugh")), "plugh");
 161     }
 162 
 163     @Test(groups = "unit")
 164     public void testFlatMapEmpty() {
 165         checkEmpty(Optional.empty().flatMap(s -> { fail(); return Optional.of(""); }));
 166     }
 167 
 168     @Test(groups = "unit")
 169     public void testFlatMapPresentReturnEmpty() {
 170         checkEmpty(Optional.of("xyzzy")
 171                            .flatMap(s -> { assertEquals(s, "xyzzy"); return Optional.empty(); }));
 172     }
 173 
 174     @Test(groups = "unit")
 175     public void testFlatMapPresentReturnPresent() {
 176         checkPresent(Optional.of("xyzzy")
 177                              .flatMap(s -> { assertEquals(s, "xyzzy"); return Optional.of("plugh"); }),
 178                      "plugh");
 179     }
 180 
 181     @Test(groups = "unit")
 182     public void testOrEmptyEmpty() {
 183         checkEmpty(Optional.<String>empty().or(() -> Optional.empty()));
 184     }
 185 
 186     @Test(groups = "unit")
 187     public void testOrEmptyPresent() {
 188         checkPresent(Optional.<String>empty().or(() -> Optional.of("plugh")), "plugh");
 189     }
 190 
 191     @Test(groups = "unit")
 192     public void testOrPresentDontCare() {
 193         checkPresent(Optional.of("xyzzy").or(() -> { fail(); return Optional.of("plugh"); }), "xyzzy");
 194     }
 195 
 196     @Test(groups = "unit")
 197     public void testStreamEmpty() {
 198         assertEquals(Optional.empty().stream().collect(toList()), List.of());
 199     }
 200 
 201     @Test(groups = "unit")
 202     public void testStreamPresent() {
 203         assertEquals(Optional.of("xyzzy").stream().collect(toList()), List.of("xyzzy"));
 204     }
 205 }