solved

src/main/java/mate/academy/service/AuthenticationService.java

@@ -1,16 +1,19 @@
 package mate.academy.service;
 
+import mate.academy.model.User;
+
 public class AuthenticationService {
-    /**
-     * Imagine that some user wants to login to your site.
-     * You should check if user credentials (login and password) are valid or not.
-     * All users are stored in <code>UserService</code> class.
-     * @param email - user's email
-     * @param password - user's password
-     * @return true if user by email exists and passed password is equal to user's password.
-     * Return false in any other cases.
-     */
+    private final UserService userService = new UserService();
+
     public boolean login(String email, String password) {
+        User testUser = userService.findByEmail(email);
+        if (testUser != null) {
+            return testUser.getPassword().equals(password);
+        }
         return false;
     }
+
+    public UserService getUserService() {
+        return userService;
+    }
 }

src/main/java/mate/academy/service/UserService.java

@@ -8,13 +8,12 @@ public class UserService {
             new User("[email protected]", "1234")
     };
 
-    /**
-     * Find user by email. All users are stored in <code>private static final User[] users</code>
-     * @param email - the input parameter
-     * @return - user if his email is equal to passed email.
-     * Return <code>null</code> if there is no suitable user
-     */
     public User findByEmail(String email) {
+        for (User user : users) {
+            if (user.getEmail().equals(email)) {
+                return user;
+            }
+        }
         return null;
     }
 }