diff --git a/pom.xml b/pom.xml
index ed086bf..c4f4f30 100644
--- a/pom.xml
+++ b/pom.xml
@@ -15,8 +15,8 @@
     </properties>
     <dependencies>
         <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
             <version>RELEASE</version>
             <scope>test</scope>
         </dependency>
diff --git a/src/main/java/com/ceticamarco/lambdatonic/Either.java b/src/main/java/com/ceticamarco/lambdatonic/Either.java
index a1df4f7..dc76ec8 100644
--- a/src/main/java/com/ceticamarco/lambdatonic/Either.java
+++ b/src/main/java/com/ceticamarco/lambdatonic/Either.java
@@ -13,5 +13,33 @@ import java.util.function.Function;
  * @param <R> The right type, representing the actual value
  */
 public sealed interface Either<L, R> permits Left, Right {
+    /**
+     * <p>
+     *      Executing an anonymous function by discriminating the Either data type value
+     * </p>
+     *
+     * @param onLeft The function to execute on the Left case
+     * @param onRight The function to execute on the Right case
+     * @return The return value of the onLeft/onRight methods
+     * @param <T> The type of the return value of the onLeft/onRight methods
+     */
     <T> T match(Function<L, T> onLeft, Function<R, T> onRight);
+
+    /**
+     * <p>
+     *     Returns true if the Either type is instantiated with the Left subtype,
+     *     false otherwise
+     * </p>
+     * @return Boolean value
+     */
+    boolean isLeft();
+
+    /**
+     * <p>
+     *     Returns true if the Either type is instantiated with the Right subtype,
+     *     false otherwise
+     * </p>
+     * @return Boolean value
+     */
+    boolean isRight();
 }
\ No newline at end of file
diff --git a/src/main/java/com/ceticamarco/lambdatonic/Left.java b/src/main/java/com/ceticamarco/lambdatonic/Left.java
index 72eba3b..255430c 100644
--- a/src/main/java/com/ceticamarco/lambdatonic/Left.java
+++ b/src/main/java/com/ceticamarco/lambdatonic/Left.java
@@ -16,4 +16,14 @@ public record Left<L, R>(L value) implements Either<L, R> {
     public <T> T match(Function<L, T> onLeft, Function<R, T> onRight) {
         return onLeft.apply(this.value);
     }
+
+    @Override
+    public boolean isLeft() {
+        return true;
+    }
+
+    @Override
+    public boolean isRight() {
+        return false;
+    }
 }
\ No newline at end of file
diff --git a/src/main/java/com/ceticamarco/lambdatonic/Right.java b/src/main/java/com/ceticamarco/lambdatonic/Right.java
index 288f07d..dd4c0cc 100644
--- a/src/main/java/com/ceticamarco/lambdatonic/Right.java
+++ b/src/main/java/com/ceticamarco/lambdatonic/Right.java
@@ -16,4 +16,14 @@ public record Right<L, R>(R value) implements Either<L, R> {
     public <T> T match(Function<L, T> onLeft, Function<R, T> onRight) {
         return onRight.apply(this.value);
     }
+
+    @Override
+    public boolean isLeft() {
+        return false;
+    }
+
+    @Override
+    public boolean isRight() {
+        return true;
+    }
 }
\ No newline at end of file
diff --git a/src/test/java/com/ceticamarco/lambdatonic/LeftTests.java b/src/test/java/com/ceticamarco/lambdatonic/LeftTests.java
index 64afce1..e98ab04 100644
--- a/src/test/java/com/ceticamarco/lambdatonic/LeftTests.java
+++ b/src/test/java/com/ceticamarco/lambdatonic/LeftTests.java
@@ -1,15 +1,23 @@
 package com.ceticamarco.lambdatonic;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.BeforeEach;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 
 public class LeftTests {
+    private Either<Integer, String> resEither;
+
+    @BeforeEach
+    public void tearUp() {
+        this.resEither = new Left<>(19);
+    }
+
     @Test
     public void testMatchLeft() {
-        Either<Integer, String> resEither = new Left<>(19);
-
-        var actual = resEither.match(
+        var actual = this.resEither.match(
             errorCode  -> "Error code: " + errorCode.toString(),
             successMsg -> successMsg
         );
@@ -18,4 +26,14 @@ public class LeftTests {
 
         assertEquals(expected, actual);
     }
+
+    @Test
+    public void testIsLeft() {
+        assertTrue(this.resEither.isLeft());
+    }
+
+    @Test
+    public void testIsRight() {
+        assertFalse(this.resEither.isRight());
+    }
 }
diff --git a/src/test/java/com/ceticamarco/lambdatonic/RightTests.java b/src/test/java/com/ceticamarco/lambdatonic/RightTests.java
index 743fcb0..ad16f48 100644
--- a/src/test/java/com/ceticamarco/lambdatonic/RightTests.java
+++ b/src/test/java/com/ceticamarco/lambdatonic/RightTests.java
@@ -1,15 +1,23 @@
 package com.ceticamarco.lambdatonic;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.BeforeEach;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 
 public class RightTests {
+    private Either<Integer, String> resEither;
+
+    @BeforeEach
+    public void tearUp() {
+        this.resEither = new Right<>("Query executed successfully");
+    }
+
     @Test
     public void testMatchRight() {
-        Either<Integer, String> resEither = new Right<>("Query executed successfully");
-
-        var actual = resEither.match(
+        var actual = this.resEither.match(
                 errorCode  -> "Error code: " + errorCode.toString(),
                 successMsg -> successMsg
         );
@@ -18,4 +26,14 @@ public class RightTests {
 
         assertEquals(expected, actual);
     }
+
+    @Test
+    public void testIsLeft() {
+        assertFalse(this.resEither.isLeft());
+    }
+
+    @Test
+    public void testIsRight() {
+        assertTrue(this.resEither.isRight());
+    }
 }