84 lines
2.9 KiB
Java
84 lines
2.9 KiB
Java
package com.baeldung.stream;
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import org.junit.Before;
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import org.junit.Test;
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import java.util.Collection;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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import java.util.Optional;
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import java.util.Set;
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import java.util.stream.Collectors;
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import java.util.stream.Stream;
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import static org.junit.Assert.assertEquals;
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import static org.junit.Assert.assertTrue;
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public class StreamMapUnitTest {
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private Map<String, String> books;
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@Before
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public void setup() {
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books = new HashMap<>();
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books.put("978-0201633610", "Design patterns : elements of reusable object-oriented software");
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books.put("978-1617291999", "Java 8 in Action: Lambdas, Streams, and functional-style programming");
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books.put("978-0134685991", "Effective Java");
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}
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@Test
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public void whenOptionalVersionCalledForExistingTitle_thenReturnOptionalWithISBN() {
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Optional<String> optionalIsbn = books.entrySet().stream()
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.filter(e -> "Effective Java".equals(e.getValue()))
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.map(Map.Entry::getKey).findFirst();
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assertEquals("978-0134685991", optionalIsbn.get());
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}
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@Test
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public void whenOptionalVersionCalledForNonExistingTitle_thenReturnEmptyOptionalForISBN() {
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Optional<String> optionalIsbn = books.entrySet().stream()
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.filter(e -> "Non Existent Title".equals(e.getValue()))
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.map(Map.Entry::getKey).findFirst();
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assertEquals(false, optionalIsbn.isPresent());
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}
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@Test
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public void whenMultipleResultsVersionCalledForExistingTitle_aCollectionWithMultipleValuesIsReturned() {
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books.put("978-0321356680", "Effective Java: Second Edition");
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List<String> isbnCodes = books.entrySet().stream()
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.filter(e -> e.getValue().startsWith("Effective Java"))
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.map(Map.Entry::getKey)
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.collect(Collectors.toList());
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assertTrue(isbnCodes.contains("978-0321356680"));
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assertTrue(isbnCodes.contains("978-0134685991"));
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}
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@Test
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public void whenMultipleResultsVersionCalledForNonExistingTitle_aCollectionWithNoValuesIsReturned() {
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List<String> isbnCodes = books.entrySet().stream()
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.filter(e -> e.getValue().startsWith("Spring"))
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.map(Map.Entry::getKey)
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.collect(Collectors.toList());
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assertTrue(isbnCodes.isEmpty());
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}
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@Test
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public void whenKeysFollowingPatternReturnsAllValuesForThoseKeys() {
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List<String> titlesForKeyPattern = books.entrySet().stream()
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.filter(e -> e.getKey().startsWith("978-0"))
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.map(Map.Entry::getValue)
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.collect(Collectors.toList());
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assertEquals(2, titlesForKeyPattern.size());
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assertTrue(titlesForKeyPattern.contains("Design patterns : elements of reusable object-oriented software"));
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assertTrue(titlesForKeyPattern.contains("Effective Java"));
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}
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}
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