BAEL-1473 (#3477)

* BAEL-1473 Intoduction to Spliterator in Java

* BAEL-1473 - Replace .out with logger.info

* removed log

* BAEL-1473 - added test-cases

* modify test-cases

core-java-8/src/test/java/com/baeldung/spliteratorAPI/ExecutorTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.spliteratorAPI;
+
+import java.util.Arrays;
+import java.util.Spliterator;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
+import static org.assertj.core.api.Assertions.*;
+import org.junit.Before;
+import org.junit.Test;
+
+public class ExecutorTest {
+	Article article;
+	Stream<Author> stream;
+	Spliterator<Author> spliterator;
+	Spliterator<Article> split1;
+	Spliterator<Article> split2;
+
+	@Before
+	public void init() {
+		article = new Article(Arrays.asList(new Author("Ahmad", 0), new Author("Eugen", 0), new Author("Alice", 1),
+				new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0),
+				new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0),
+				new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1),
+				new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1),
+				new Author("Mike", 0), new Author("Michał", 0), new Author("Loredana", 1)), 0);
+		stream = article.getListOfAuthors().stream();
+		split1 = Executor.generateElements().spliterator();
+		split2 = split1.trySplit();
+		spliterator = new RelatedAuthorSpliterator(article.getListOfAuthors());
+	}
+
+	@Test
+	public void givenAstreamOfAuthors_whenProcessedInParallelWithCustomSpliterator_coubtProducessRightOutput() {
+		Stream<Author> stream2 = StreamSupport.stream(spliterator, true);
+		assertThat(Executor.countAutors(stream2.parallel())).isEqualTo(9);
+	}
+
+	@Test
+	public void givenSpliterator_whenAppliedToAListOfArticle_thenSplittedInHalf() {
+		assertThat(new Task(split1).call()).containsSequence(Executor.generateElements().size() / 2 + "");
+		assertThat(new Task(split2).call()).containsSequence(Executor.generateElements().size() / 2 + "");
+	}
+}