Merge pull request #9030 from gindex/master

BAEL-3940 How to get String from Mono<String> in reactive java

reactor-core/src/test/java/com/baeldung/mono/MonoUnitTest.java

@@ -0,0 +1,43 @@
+package com.baeldung.mono;
+
+import org.junit.Test;
+import reactor.core.publisher.Mono;
+
+import java.time.Duration;
+import java.time.temporal.ChronoUnit;
+import java.util.Optional;
+
+import static org.junit.Assert.assertEquals;
+
+public class MonoUnitTest {
+    @Test
+    public void whenMonoProducesString_thenBlockAndConsume() {
+
+        String result1 = blockingHelloWorld().block();
+        assertEquals("Hello world!", result1);
+
+        String result2 = blockingHelloWorld()
+                .block(Duration.of(1000, ChronoUnit.MILLIS));
+        assertEquals("Hello world!", result2);
+
+        Optional<String> result3 = Mono.<String>empty().blockOptional();
+        assertEquals(Optional.empty(), result3);
+    }
+
+    @Test
+    public void whenMonoProducesString_thenConsumeNonBlocking() {
+
+        blockingHelloWorld()
+                .doOnNext(result -> assertEquals("Hello world!", result))
+                .subscribe();
+
+        blockingHelloWorld()
+                .subscribe(result -> assertEquals("Hello world!", result));
+
+    }
+
+    private Mono<String> blockingHelloWorld() {
+        // blocking
+        return Mono.just("Hello world!");
+    }
+}