Merge pull request #4988 from shreyasm/forked1

BAEL-1875 - Shreyas Mahajan - Adding unit tests for comparing flatmap and switchmap in RxJava

rxjava/src/test/java/com/baeldung/rxjava/operators/RxFlatmapAndSwitchmapUnitTest.java

@@ -0,0 +1,65 @@
+package com.baeldung.rxjava.operators;
+
+import io.reactivex.Observable;
+import io.reactivex.schedulers.TestScheduler;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+import static org.hamcrest.CoreMatchers.hasItems;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+
+public class RxFlatmapAndSwitchmapUnitTest {
+    @Test
+    public void givenObservable_whenFlatmap_shouldAssertAllItemsReturned() {
+        //given
+        List<String> actualOutput = new ArrayList<>();
+        final TestScheduler scheduler = new TestScheduler();
+        final List<String> keywordToSearch = Arrays.asList("b", "bo", "boo", "book", "books");
+
+        //when
+        Observable.fromIterable(keywordToSearch)
+          .flatMap(s -> Observable
+            .just(s + " FirstResult", s + " SecondResult")
+            .delay(10, TimeUnit.SECONDS, scheduler))
+          .toList()
+          .doOnSuccess(s -> actualOutput.addAll(s))
+          .subscribe();
+
+        scheduler.advanceTimeBy(1, TimeUnit.MINUTES);
+
+        //then
+        assertThat(actualOutput, hasItems("b FirstResult", "b SecondResult",
+          "boo FirstResult", "boo SecondResult",
+          "bo FirstResult", "bo SecondResult",
+          "book FirstResult", "book SecondResult",
+          "books FirstResult", "books SecondResult"));
+    }
+
+    @Test
+    public void givenObservable_whenSwitchmap_shouldAssertLatestItemReturned() {
+        //given
+        List<String> actualOutput = new ArrayList<>();
+        final TestScheduler scheduler = new TestScheduler();
+        final List<String> keywordToSearch = Arrays.asList("b", "bo", "boo", "book", "books");
+
+        //when
+        Observable.fromIterable(keywordToSearch)
+          .switchMap(s -> Observable
+            .just(s + " FirstResult", s + " SecondResult")
+            .delay(10, TimeUnit.SECONDS, scheduler))
+          .toList()
+          .doOnSuccess(s -> actualOutput.addAll(s))
+          .subscribe();
+
+        scheduler.advanceTimeBy(1, TimeUnit.MINUTES);
+
+        //then
+        assertEquals(2, actualOutput.size());
+        assertThat(actualOutput, hasItems("books FirstResult", "books SecondResult"));
+    }
+}