JAVA-13636 Updated Junit5 article

testing-modules/mockito-simple/src/test/java/com/baeldung/junit5/mockito/UserServiceUnitTest.java

@@ -1,6 +1,7 @@
 package com.baeldung.junit5.mockito;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.fail;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.lenient;
@@ -8,7 +9,6 @@ import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
-import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
@@ -26,21 +26,28 @@ import com.baeldung.junit5.mockito.service.Errors;
 import com.baeldung.junit5.mockito.service.UserService;
 
 @ExtendWith(MockitoExtension.class)
-public class UserServiceUnitTest {
+class UserServiceUnitTest {
 
     UserService userService;
+    
     SettingRepository settingRepository;
-    @Mock UserRepository userRepository;
-    @Mock MailClient mailClient;
+    
+    @Mock
+    UserRepository userRepository;
+    
+    @Mock
+    MailClient mailClient;
 
     User user;
 
     @BeforeEach
     void init(@Mock SettingRepository settingRepository) {
         userService = new DefaultUserService(userRepository, settingRepository, mailClient);
-        lenient().when(settingRepository.getUserMinAge()).thenReturn(10);
+        lenient().when(settingRepository.getUserMinAge())
+            .thenReturn(10);
         when(settingRepository.getUserNameMinLength()).thenReturn(4);
-        lenient().when(userRepository.isUsernameAlreadyExists(any(String.class))).thenReturn(false);
+        lenient().when(userRepository.isUsernameAlreadyExists(any(String.class)))
+            .thenReturn(false);
         this.settingRepository = settingRepository;
     }
 
@@ -66,7 +73,7 @@ public class UserServiceUnitTest {
 
         // Then
         verify(userRepository).insert(user);
-        Assertions.assertNotNull(user.getId());
+        assertNotNull(user.getId());
         verify(mailClient).sendUserRegistrationMail(insertedUser);
     }
 
@@ -80,7 +87,7 @@ public class UserServiceUnitTest {
             userService.register(user);
             fail("Should give an error");
         } catch (Exception ex) {
-            assertEquals(ex.getMessage(), Errors.USER_NAME_SHORT);
+            assertThat(ex.getMessage()).isEqualTo(Errors.USER_NAME_SHORT);
         }
 
         // Then
@@ -97,7 +104,7 @@ public class UserServiceUnitTest {
             userService.register(user);
             fail("Should give an error");
         } catch (Exception ex) {
-            assertEquals(ex.getMessage(), Errors.USER_AGE_YOUNG);
+            assertThat(ex.getMessage()).isEqualTo(Errors.USER_AGE_YOUNG);
         }
 
         // Then
@@ -116,7 +123,7 @@ public class UserServiceUnitTest {
             userService.register(user);
             fail("Should give an error");
         } catch (Exception ex) {
-            assertEquals(ex.getMessage(), Errors.USER_NAME_DUPLICATE);
+            assertThat(ex.getMessage()).isEqualTo(Errors.USER_NAME_DUPLICATE);
         }
 
         // Then