diff --git a/src/test/java/option/OptionalExample.java b/src/test/java/option/OptionalExample.java
index db18993..ec02922 100644
--- a/src/test/java/option/OptionalExample.java
+++ b/src/test/java/option/OptionalExample.java
@@ -5,6 +5,7 @@
 import java.util.Optional;
 import java.util.concurrent.ThreadLocalRandom;
 import java.util.function.Function;
+import java.util.function.Predicate;
 
 import static org.junit.Assert.assertEquals;
 
@@ -50,9 +51,66 @@ public void map() {
         assertEquals(expected, actual);
     }
 
+    @Test
+    public void flatMap() {
+        final Optional<String> optional = getOptional();
+
+        final Function<String, Optional<Integer>> getLength = s -> Optional.of(s.length());
+
+        final Optional<Integer> expected = optional.flatMap(getLength);
+
+        final Optional<Integer> actual;
+
+        if (optional.isPresent()) {
+            actual = getLength.apply(optional.get());
+        } else {
+            actual = Optional.empty();
+        }
+
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void filter() {
+        final Optional<String> optional = getOptional();
+
+        final Predicate<String> predicate = String::isEmpty;
+
+        final Optional<String> expected = optional.filter(predicate);
+
+        final Optional<String> actual;
+
+        if (optional.isPresent() && predicate.test(optional.get())) {
+            actual = optional;
+        } else {
+            actual = Optional.empty();
+        }
+
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void orElse() {
+        final Optional<String> optional = getOptional();
+
+        final String param = "defg";
+
+        final String expected = optional.orElse(param);
+
+        final String actual;
+
+        if (optional.isPresent()) {
+            actual = optional.get();
+        } else {
+            actual = param;
+        }
+
+        assertEquals(expected, actual);
+    }
+
     private Optional<String> getOptional() {
         return ThreadLocalRandom.current().nextBoolean()
-            ? Optional.empty()
-            : Optional.of("abc");
+                ? Optional.empty()
+                : Optional.of("abc");
     }
 }