backend/src/main/java/com/petshop/backend/service/CustomerService.java

@@ -60,15 +60,7 @@ public class CustomerService {
         customer.setEmail(request.getEmail());
 
         customer = customerRepository.save(customer);
-        Customer savedCustomer = customer;
-        User user = userRepository.findByEmail(savedCustomer.getEmail())
-                .map(existing -> {
-                    if (existing.getRole() != User.Role.CUSTOMER) {
-                        throw new ResponseStatusException(CONFLICT, "Email already exists for a different account type");
-                    }
-                    return existing;
-                })
-                .orElseGet(() -> createLinkedUser(savedCustomer));
+        User user = createLinkedUser(customer);
 
         Customer linkedCustomer = userBusinessLinkageService.ensureLinkedCustomer(user);
         syncLinkedUser(linkedCustomer);
@@ -93,9 +85,14 @@ public class CustomerService {
 
     @Transactional
     public void deleteCustomer(Long id) {
-        if (!customerRepository.existsById(id)) {
-            throw new ResourceNotFoundException("Customer not found with id: " + id);
+        Customer customer = customerRepository.findById(id)
+                .orElseThrow(() -> new ResourceNotFoundException("Customer not found with id: " + id));
+
+        if (customer.getUserId() != null && userRepository.existsById(customer.getUserId())) {
+            userRepository.deleteById(customer.getUserId());
+            return;
         }
+
         customerRepository.deleteById(id);
     }
 

backend/src/test/java/com/petshop/backend/service/CustomerServiceTest.java

@@ -20,6 +20,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
@@ -147,4 +148,33 @@ class CustomerServiceTest {
 
         assertThrows(ResponseStatusException.class, () -> customerService.updateCustomer(7L, request));
     }
+
+    @Test
+    void deleteCustomerDeletesLinkedUser() {
+        Customer customer = new Customer();
+        customer.setCustomerId(7L);
+        customer.setUserId(11L);
+
+        when(customerRepository.findById(7L)).thenReturn(Optional.of(customer));
+        when(userRepository.existsById(11L)).thenReturn(true);
+
+        customerService.deleteCustomer(7L);
+
+        verify(userRepository).deleteById(11L);
+        verify(customerRepository, never()).deleteById(7L);
+    }
+
+    @Test
+    void deleteCustomerDeletesCustomerWhenNoLinkedUserExists() {
+        Customer customer = new Customer();
+        customer.setCustomerId(7L);
+        customer.setUserId(11L);
+
+        when(customerRepository.findById(7L)).thenReturn(Optional.of(customer));
+        when(userRepository.existsById(11L)).thenReturn(false);
+
+        customerService.deleteCustomer(7L);
+
+        verify(customerRepository).deleteById(7L);
+    }
 }