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Refactor Java8GroupingByCollectorUnitTest

This commit is contained in:
pivovarit 2017-02-07 19:32:09 +01:00
parent 66065b6110
commit 92ad8123f1
1 changed files with 154 additions and 73 deletions
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227
core-java/src/test/java/com/baeldung/java8/Java8GroupingByCollectorUnitTest.java
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@ -1,52 +1,47 @@
package com.baeldung.java8; package com.baeldung.java8;
import static java.util.Comparator.comparingInt;
import static java.util.stream.Collectors.averagingInt;
import static java.util.stream.Collectors.counting;
import static java.util.stream.Collectors.groupingBy;
import static java.util.stream.Collectors.groupingByConcurrent;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.mapping;
import static java.util.stream.Collectors.maxBy;
import static java.util.stream.Collectors.summarizingInt;
import static java.util.stream.Collectors.summingInt;
import static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.toSet;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;
import java.util.Arrays;
import java.util.EnumMap;
import java.util.IntSummaryStatistics;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.ConcurrentMap;
import org.junit.Test;
import com.baeldung.java_8_features.groupingby.BlogPost; import com.baeldung.java_8_features.groupingby.BlogPost;
import com.baeldung.java_8_features.groupingby.BlogPostType; import com.baeldung.java_8_features.groupingby.BlogPostType;
import org.junit.Test;
import java.util.*;
import java.util.concurrent.ConcurrentMap;
import static java.util.Comparator.comparingInt;
import static java.util.stream.Collectors.*;
import static org.junit.Assert.*;
public class Java8GroupingByCollectorUnitTest { public class Java8GroupingByCollectorUnitTest {
private static final List<BlogPost> POSTS = Arrays.asList(new BlogPost("News item 1", "Author 1", BlogPostType.NEWS, 15), new BlogPost("Tech review 1", "Author 2", BlogPostType.REVIEW, 5), private static final List<BlogPost> posts = Arrays.asList(
new BlogPost("Programming guide", "Author 1", BlogPostType.GUIDE, 20), new BlogPost("News item 2", "Author 2", BlogPostType.NEWS, 35), new BlogPost("Tech review 2", "Author 1", BlogPostType.REVIEW, 15)); new BlogPost("News item 1", "Author 1", BlogPostType.NEWS, 15),
new BlogPost("Tech review 1", "Author 2", BlogPostType.REVIEW, 5),
new BlogPost("Programming guide", "Author 1", BlogPostType.GUIDE, 20),
new BlogPost("News item 2", "Author 2", BlogPostType.NEWS, 35),
new BlogPost("Tech review 2", "Author 1", BlogPostType.REVIEW, 15));
@Test @Test
public void givenAListOfPosts_whenGroupedByType_thenGetAMapBetweenTypeAndPosts() { public void givenAListOfPosts_whenGroupedByType_thenGetAMapBetweenTypeAndPosts() {
Map<BlogPostType, List<BlogPost>> postsPerType = POSTS.stream().collect(groupingBy(BlogPost::getType)); Map<BlogPostType, List<BlogPost>> postsPerType = posts
.stream()
.collect(groupingBy(BlogPost::getType));
assertEquals(2, postsPerType.get(BlogPostType.NEWS).size()); assertEquals(2, postsPerType
assertEquals(1, postsPerType.get(BlogPostType.GUIDE).size()); .get(BlogPostType.NEWS)
assertEquals(2, postsPerType.get(BlogPostType.REVIEW).size()); .size());
assertEquals(1, postsPerType
.get(BlogPostType.GUIDE)
.size());
assertEquals(2, postsPerType
.get(BlogPostType.REVIEW)
.size());
} }
@Test @Test
public void givenAListOfPosts_whenGroupedByTypeAndTheirTitlesAreJoinedInAString_thenGetAMapBetweenTypeAndCsvTitles() { public void givenAListOfPosts_whenGroupedByTypeAndTheirTitlesAreJoinedInAString_thenGetAMapBetweenTypeAndCsvTitles() {
Map<BlogPostType, String> postsPerType = POSTS.stream().collect(groupingBy(BlogPost::getType, mapping(BlogPost::getTitle, joining(", ", "Post titles: [", "]")))); Map<BlogPostType, String> postsPerType = posts
.stream()
.collect(groupingBy(BlogPost::getType, mapping(BlogPost::getTitle, joining(", ", "Post titles: [", "]"))));
assertEquals("Post titles: [News item 1, News item 2]", postsPerType.get(BlogPostType.NEWS)); assertEquals("Post titles: [News item 1, News item 2]", postsPerType.get(BlogPostType.NEWS));
assertEquals("Post titles: [Programming guide]", postsPerType.get(BlogPostType.GUIDE)); assertEquals("Post titles: [Programming guide]", postsPerType.get(BlogPostType.GUIDE));
@ -55,88 +50,174 @@ public class Java8GroupingByCollectorUnitTest {
@Test @Test
public void givenAListOfPosts_whenGroupedByTypeAndSumTheLikes_thenGetAMapBetweenTypeAndPostLikes() { public void givenAListOfPosts_whenGroupedByTypeAndSumTheLikes_thenGetAMapBetweenTypeAndPostLikes() {
Map<BlogPostType, Integer> likesPerType = POSTS.stream().collect(groupingBy(BlogPost::getType, summingInt(BlogPost::getLikes))); Map<BlogPostType, Integer> likesPerType = posts
.stream()
.collect(groupingBy(BlogPost::getType, summingInt(BlogPost::getLikes)));
assertEquals(50, likesPerType.get(BlogPostType.NEWS).intValue()); assertEquals(50, likesPerType
assertEquals(20, likesPerType.get(BlogPostType.REVIEW).intValue()); .get(BlogPostType.NEWS)
assertEquals(20, likesPerType.get(BlogPostType.GUIDE).intValue()); .intValue());
assertEquals(20, likesPerType
.get(BlogPostType.REVIEW)
.intValue());
assertEquals(20, likesPerType
.get(BlogPostType.GUIDE)
.intValue());
} }
@Test @Test
public void givenAListOfPosts_whenGroupedByTypeInAnEnumMap_thenGetAnEnumMapBetweenTypeAndPosts() { public void givenAListOfPosts_whenGroupedByTypeInAnEnumMap_thenGetAnEnumMapBetweenTypeAndPosts() {
EnumMap<BlogPostType, List<BlogPost>> postsPerType = POSTS.stream().collect(groupingBy(BlogPost::getType, () -> new EnumMap<>(BlogPostType.class), toList())); EnumMap<BlogPostType, List<BlogPost>> postsPerType = posts
.stream()
.collect(groupingBy(BlogPost::getType, () -> new EnumMap<>(BlogPostType.class), toList()));
assertEquals(2, postsPerType.get(BlogPostType.NEWS).size()); assertEquals(2, postsPerType
assertEquals(1, postsPerType.get(BlogPostType.GUIDE).size()); .get(BlogPostType.NEWS)
assertEquals(2, postsPerType.get(BlogPostType.REVIEW).size()); .size());
assertEquals(1, postsPerType
.get(BlogPostType.GUIDE)
.size());
assertEquals(2, postsPerType
.get(BlogPostType.REVIEW)
.size());
} }
@Test @Test
public void givenAListOfPosts_whenGroupedByTypeInSets_thenGetAMapBetweenTypesAndSetsOfPosts() { public void givenAListOfPosts_whenGroupedByTypeInSets_thenGetAMapBetweenTypesAndSetsOfPosts() {
Map<BlogPostType, Set<BlogPost>> postsPerType = POSTS.stream().collect(groupingBy(BlogPost::getType, toSet())); Map<BlogPostType, Set<BlogPost>> postsPerType = posts
.stream()
.collect(groupingBy(BlogPost::getType, toSet()));
assertEquals(2, postsPerType.get(BlogPostType.NEWS).size()); assertEquals(2, postsPerType
assertEquals(1, postsPerType.get(BlogPostType.GUIDE).size()); .get(BlogPostType.NEWS)
assertEquals(2, postsPerType.get(BlogPostType.REVIEW).size()); .size());
assertEquals(1, postsPerType
.get(BlogPostType.GUIDE)
.size());
assertEquals(2, postsPerType
.get(BlogPostType.REVIEW)
.size());
} }
@Test @Test
public void givenAListOfPosts_whenGroupedByTypeConcurrently_thenGetAMapBetweenTypeAndPosts() { public void givenAListOfPosts_whenGroupedByTypeConcurrently_thenGetAMapBetweenTypeAndPosts() {
ConcurrentMap<BlogPostType, List<BlogPost>> postsPerType = POSTS.parallelStream().collect(groupingByConcurrent(BlogPost::getType)); ConcurrentMap<BlogPostType, List<BlogPost>> postsPerType = posts
.parallelStream()
.collect(groupingByConcurrent(BlogPost::getType));
assertEquals(2, postsPerType.get(BlogPostType.NEWS).size()); assertEquals(2, postsPerType
assertEquals(1, postsPerType.get(BlogPostType.GUIDE).size()); .get(BlogPostType.NEWS)
assertEquals(2, postsPerType.get(BlogPostType.REVIEW).size()); .size());
assertEquals(1, postsPerType
.get(BlogPostType.GUIDE)
.size());
assertEquals(2, postsPerType
.get(BlogPostType.REVIEW)
.size());
} }
@Test @Test
public void givenAListOfPosts_whenGroupedByTypeAndAveragingLikes_thenGetAMapBetweenTypeAndAverageNumberOfLikes() { public void givenAListOfPosts_whenGroupedByTypeAndAveragingLikes_thenGetAMapBetweenTypeAndAverageNumberOfLikes() {
Map<BlogPostType, Double> averageLikesPerType = POSTS.stream().collect(groupingBy(BlogPost::getType, averagingInt(BlogPost::getLikes))); Map<BlogPostType, Double> averageLikesPerType = posts
.stream()
.collect(groupingBy(BlogPost::getType, averagingInt(BlogPost::getLikes)));
assertEquals(25, averageLikesPerType.get(BlogPostType.NEWS).intValue()); assertEquals(25, averageLikesPerType
assertEquals(20, averageLikesPerType.get(BlogPostType.GUIDE).intValue()); .get(BlogPostType.NEWS)
assertEquals(10, averageLikesPerType.get(BlogPostType.REVIEW).intValue()); .intValue());
assertEquals(20, averageLikesPerType
.get(BlogPostType.GUIDE)
.intValue());
assertEquals(10, averageLikesPerType
.get(BlogPostType.REVIEW)
.intValue());
} }
@Test @Test
public void givenAListOfPosts_whenGroupedByTypeAndCounted_thenGetAMapBetweenTypeAndNumberOfPosts() { public void givenAListOfPosts_whenGroupedByTypeAndCounted_thenGetAMapBetweenTypeAndNumberOfPosts() {
Map<BlogPostType, Long> numberOfPostsPerType = POSTS.stream().collect(groupingBy(BlogPost::getType, counting())); Map<BlogPostType, Long> numberOfPostsPerType = posts
.stream()
.collect(groupingBy(BlogPost::getType, counting()));
assertEquals(2, numberOfPostsPerType.get(BlogPostType.NEWS).intValue()); assertEquals(2, numberOfPostsPerType
assertEquals(1, numberOfPostsPerType.get(BlogPostType.GUIDE).intValue()); .get(BlogPostType.NEWS)
assertEquals(2, numberOfPostsPerType.get(BlogPostType.REVIEW).intValue()); .intValue());
assertEquals(1, numberOfPostsPerType
.get(BlogPostType.GUIDE)
.intValue());
assertEquals(2, numberOfPostsPerType
.get(BlogPostType.REVIEW)
.intValue());
} }
@Test @Test
public void givenAListOfPosts_whenGroupedByTypeAndMaxingLikes_thenGetAMapBetweenTypeAndMaximumNumberOfLikes() { public void givenAListOfPosts_whenGroupedByTypeAndMaxingLikes_thenGetAMapBetweenTypeAndMaximumNumberOfLikes() {
Map<BlogPostType, Optional<BlogPost>> maxLikesPerPostType = POSTS.stream().collect(groupingBy(BlogPost::getType, maxBy(comparingInt(BlogPost::getLikes)))); Map<BlogPostType, Optional<BlogPost>> maxLikesPerPostType = posts
.stream()
.collect(groupingBy(BlogPost::getType, maxBy(comparingInt(BlogPost::getLikes))));
assertTrue(maxLikesPerPostType.get(BlogPostType.NEWS).isPresent()); assertTrue(maxLikesPerPostType
assertEquals(35, maxLikesPerPostType.get(BlogPostType.NEWS).get().getLikes()); .get(BlogPostType.NEWS)
.isPresent());
assertEquals(35, maxLikesPerPostType
.get(BlogPostType.NEWS)
.get()
.getLikes());
assertTrue(maxLikesPerPostType.get(BlogPostType.GUIDE).isPresent()); assertTrue(maxLikesPerPostType
assertEquals(20, maxLikesPerPostType.get(BlogPostType.GUIDE).get().getLikes()); .get(BlogPostType.GUIDE)
.isPresent());
assertEquals(20, maxLikesPerPostType
.get(BlogPostType.GUIDE)
.get()
.getLikes());
assertTrue(maxLikesPerPostType.get(BlogPostType.REVIEW).isPresent()); assertTrue(maxLikesPerPostType
assertEquals(15, maxLikesPerPostType.get(BlogPostType.REVIEW).get().getLikes()); .get(BlogPostType.REVIEW)
.isPresent());
assertEquals(15, maxLikesPerPostType
.get(BlogPostType.REVIEW)
.get()
.getLikes());
} }
@Test @Test
public void givenAListOfPosts_whenGroupedByAuthorAndThenByType_thenGetAMapBetweenAuthorAndMapsBetweenTypeAndBlogPosts() { public void givenAListOfPosts_whenGroupedByAuthorAndThenByType_thenGetAMapBetweenAuthorAndMapsBetweenTypeAndBlogPosts() {
Map<String, Map<BlogPostType, List<BlogPost>>> map = POSTS.stream().collect(groupingBy(BlogPost::getAuthor, groupingBy(BlogPost::getType))); Map<String, Map<BlogPostType, List<BlogPost>>> map = posts
.stream()
.collect(groupingBy(BlogPost::getAuthor, groupingBy(BlogPost::getType)));
assertEquals(1, map.get("Author 1").get(BlogPostType.NEWS).size()); assertEquals(1, map
assertEquals(1, map.get("Author 1").get(BlogPostType.GUIDE).size()); .get("Author 1")
assertEquals(1, map.get("Author 1").get(BlogPostType.REVIEW).size()); .get(BlogPostType.NEWS)
.size());
assertEquals(1, map
.get("Author 1")
.get(BlogPostType.GUIDE)
.size());
assertEquals(1, map
.get("Author 1")
.get(BlogPostType.REVIEW)
.size());
assertEquals(1, map.get("Author 2").get(BlogPostType.NEWS).size()); assertEquals(1, map
assertEquals(1, map.get("Author 2").get(BlogPostType.REVIEW).size()); .get("Author 2")
assertNull(map.get("Author 2").get(BlogPostType.GUIDE)); .get(BlogPostType.NEWS)
.size());
assertEquals(1, map
.get("Author 2")
.get(BlogPostType.REVIEW)
.size());
assertNull(map
.get("Author 2")
.get(BlogPostType.GUIDE));
} }
@Test @Test
public void givenAListOfPosts_whenGroupedByTypeAndSummarizingLikes_thenGetAMapBetweenTypeAndSummary() { public void givenAListOfPosts_whenGroupedByTypeAndSummarizingLikes_thenGetAMapBetweenTypeAndSummary() {
Map<BlogPostType, IntSummaryStatistics> likeStatisticsPerType = POSTS.stream().collect(groupingBy(BlogPost::getType, summarizingInt(BlogPost::getLikes))); Map<BlogPostType, IntSummaryStatistics> likeStatisticsPerType = posts
.stream()
.collect(groupingBy(BlogPost::getType, summarizingInt(BlogPost::getLikes)));
IntSummaryStatistics newsLikeStatistics = likeStatisticsPerType.get(BlogPostType.NEWS); IntSummaryStatistics newsLikeStatistics = likeStatisticsPerType.get(BlogPostType.NEWS);