diff --git a/idempotent-consumer/src/main/java/com/iluwatar/idempotentconsumer/Request.java b/idempotent-consumer/src/main/java/com/iluwatar/idempotentconsumer/Request.java
index 484b79550823..29f5d6fba375 100644
--- a/idempotent-consumer/src/main/java/com/iluwatar/idempotentconsumer/Request.java
+++ b/idempotent-consumer/src/main/java/com/iluwatar/idempotentconsumer/Request.java
@@ -41,8 +41,7 @@ public class Request {
   enum Status {
     PENDING,
     STARTED,
-    COMPLETED,
-    INERROR
+    COMPLETED
   }
 
   @Id
diff --git a/idempotent-consumer/src/test/java/com/iluwatar/idempotentconsumer/AppTest.java b/idempotent-consumer/src/test/java/com/iluwatar/idempotentconsumer/AppTest.java
new file mode 100644
index 000000000000..e161b2edc30d
--- /dev/null
+++ b/idempotent-consumer/src/test/java/com/iluwatar/idempotentconsumer/AppTest.java
@@ -0,0 +1,46 @@
+package com.iluwatar.idempotentconsumer;
+
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+import org.springframework.boot.CommandLineRunner;
+
+import java.util.UUID;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+/**
+ * Application test
+ */
+class AppTest {
+
+  @Test
+  void main() {
+    assertDoesNotThrow(() -> App.main(new String[] {}));
+  }
+
+  @Test
+  void run() throws Exception {
+    RequestService requestService = Mockito.mock(RequestService.class);
+    RequestRepository requestRepository = Mockito.mock(RequestRepository.class);
+    UUID uuid = UUID.randomUUID();
+    Request requestPending = new Request(uuid);
+    Request requestStarted = new Request(uuid, Request.Status.STARTED);
+    Request requestCompleted = new Request(uuid, Request.Status.COMPLETED);
+    when(requestService.create(any())).thenReturn(requestPending);
+    when(requestService.start(any())).thenReturn(requestStarted);
+    when(requestService.complete(any())).thenReturn(requestCompleted);
+
+    CommandLineRunner runner = new App().run(requestService, requestRepository);
+
+    runner.run();
+
+    verify(requestService, times(3)).create(any());
+    verify(requestService, times(2)).start(any());
+    verify(requestService, times(1)).complete(any());
+    verify(requestRepository, times(1)).count();
+  }
+}
\ No newline at end of file
diff --git a/idempotent-consumer/src/test/java/com/iluwatar/idempotentconsumer/RequestStateMachineTests.java b/idempotent-consumer/src/test/java/com/iluwatar/idempotentconsumer/RequestStateMachineTests.java
new file mode 100644
index 000000000000..af779648c8a3
--- /dev/null
+++ b/idempotent-consumer/src/test/java/com/iluwatar/idempotentconsumer/RequestStateMachineTests.java
@@ -0,0 +1,59 @@
+package com.iluwatar.idempotentconsumer;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import java.util.UUID;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+class RequestStateMachineTests {
+  private RequestStateMachine requestStateMachine;
+
+  @BeforeEach
+  public void setUp() {
+    requestStateMachine = new RequestStateMachine();
+  }
+
+  @Test
+  void transitionPendingToStarted() {
+    Request startedRequest = requestStateMachine.next(new Request(UUID.randomUUID(), Request.Status.PENDING),
+        Request.Status.STARTED);
+    assertEquals(Request.Status.STARTED, startedRequest.getStatus());
+  }
+
+  @Test
+  void transitionAnyToPending_shouldThrowError() {
+    assertThrows(InvalidNextStateException.class,
+        () -> requestStateMachine.next(new Request(UUID.randomUUID(), Request.Status.PENDING),
+            Request.Status.PENDING));
+    assertThrows(InvalidNextStateException.class,
+        () -> requestStateMachine.next(new Request(UUID.randomUUID(), Request.Status.STARTED),
+            Request.Status.PENDING));
+    assertThrows(InvalidNextStateException.class,
+        () -> requestStateMachine.next(new Request(UUID.randomUUID(), Request.Status.COMPLETED),
+            Request.Status.PENDING));
+  }
+
+  @Test
+  void transitionCompletedToAny_shouldThrowError() {
+    assertThrows(InvalidNextStateException.class,
+        () -> requestStateMachine.next(new Request(UUID.randomUUID(), Request.Status.COMPLETED),
+            Request.Status.PENDING));
+    assertThrows(InvalidNextStateException.class,
+        () -> requestStateMachine.next(new Request(UUID.randomUUID(), Request.Status.COMPLETED),
+            Request.Status.STARTED));
+    assertThrows(InvalidNextStateException.class,
+        () -> requestStateMachine.next(new Request(UUID.randomUUID(), Request.Status.COMPLETED),
+            Request.Status.COMPLETED));
+  }
+
+  @Test
+  void transitionStartedToCompleted() {
+    Request completedRequest = requestStateMachine.next(new Request(UUID.randomUUID(), Request.Status.STARTED),
+        Request.Status.COMPLETED);
+    assertEquals(Request.Status.COMPLETED, completedRequest.getStatus());
+  }
+
+
+}
\ No newline at end of file