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| 1 | +package lambdasinaction.chap10; |
| 2 | + |
| 3 | +import org.junit.Test; |
| 4 | + |
| 5 | +import java.util.Arrays; |
| 6 | +import java.util.Optional; |
| 7 | +import java.util.Set; |
| 8 | + |
| 9 | +import static org.junit.Assert.*; |
| 10 | + |
| 11 | +public class OptionalTest { |
| 12 | + |
| 13 | + @Test |
| 14 | + public void getCarInsuranceNameWithEmptyPerson() { |
| 15 | + OptionalMain main = new OptionalMain(); |
| 16 | + String result = main.getCarInsuranceName(Optional.empty()); |
| 17 | + assertEquals("Unknown", result); |
| 18 | + } |
| 19 | + |
| 20 | + @Test |
| 21 | + public void optionalOfNullable() { |
| 22 | + Optional<String> opt = Optional.ofNullable(null); |
| 23 | + assertFalse(opt.isPresent()); |
| 24 | + |
| 25 | + Optional<String> present = Optional.ofNullable("hello"); |
| 26 | + assertTrue(present.isPresent()); |
| 27 | + assertEquals("hello", present.get()); |
| 28 | + } |
| 29 | + |
| 30 | + @Test |
| 31 | + public void optionalMap() { |
| 32 | + Optional<String> name = Optional.of("Java"); |
| 33 | + Optional<Integer> len = name.map(String::length); |
| 34 | + assertEquals(Integer.valueOf(4), len.get()); |
| 35 | + } |
| 36 | + |
| 37 | + @Test |
| 38 | + public void optionalFlatMap() { |
| 39 | + Optional<Optional<String>> nested = Optional.of(Optional.of("nested")); |
| 40 | + Optional<String> flat = nested.flatMap(x -> x); |
| 41 | + assertEquals("nested", flat.get()); |
| 42 | + } |
| 43 | + |
| 44 | + @Test |
| 45 | + public void optionalOrElse() { |
| 46 | + Optional<String> empty = Optional.empty(); |
| 47 | + assertEquals("default", empty.orElse("default")); |
| 48 | + |
| 49 | + Optional<String> present = Optional.of("value"); |
| 50 | + assertEquals("value", present.orElse("default")); |
| 51 | + } |
| 52 | + |
| 53 | + @Test |
| 54 | + public void optionalFilter() { |
| 55 | + Optional<String> opt = Optional.of("hello"); |
| 56 | + assertTrue(opt.filter(s -> s.startsWith("h")).isPresent()); |
| 57 | + assertFalse(opt.filter(s -> s.startsWith("z")).isPresent()); |
| 58 | + } |
| 59 | + |
| 60 | + @Test |
| 61 | + public void optionalIfPresent() { |
| 62 | + Optional<String> opt = Optional.of("test"); |
| 63 | + StringBuilder sb = new StringBuilder(); |
| 64 | + opt.ifPresent(sb::append); |
| 65 | + assertEquals("test", sb.toString()); |
| 66 | + } |
| 67 | + |
| 68 | + @Test |
| 69 | + public void optionalStream() { |
| 70 | + Optional<String> present = Optional.of("value"); |
| 71 | + long count = present.stream().count(); |
| 72 | + assertEquals(1, count); |
| 73 | + |
| 74 | + Optional<String> empty = Optional.empty(); |
| 75 | + long emptyCount = empty.stream().count(); |
| 76 | + assertEquals(0, emptyCount); |
| 77 | + } |
| 78 | + |
| 79 | + @Test |
| 80 | + public void insuranceNameAccess() { |
| 81 | + Insurance insurance = new Insurance(); |
| 82 | + assertNull(insurance.getName()); |
| 83 | + } |
| 84 | +} |
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