Add the response for create command and the test.

features/backup_plan_cli_add.feature

@@ -13,3 +13,16 @@ Feature: Creating a backup plan with the CLI
       | plans add --label my_label --source /mnt -d /mnt2 -d /mnt3 |
       | plans add --label label2   --source /mnt -d /mnt2 -d /mnt3 |
 
+  @fixture.injector
+  @fixture.in_memory_database
+  @fixture.cli
+  Scenario Outline: Response of create an new unique backup plan with the CLI
+    Given the CLI arguments are "<arguments>"
+    When I run the CLI
+    Then the CLI executed with "<result>"
+    And the CLI output contains "<result_message>"
+
+    Examples:
+      | arguments                                                  | result  | result_message            | description |
+      | plans add --label my_label --source /mnt -d /mnt2 -d /mnt3 | success | The backup plan is added. | add a plan  |
+

tui_rsync/user_interface/cli/components/backup_plan/add_backup_plan.py

@@ -61,3 +61,4 @@ def add(
     plan = BackupPlan(label=Label(label), source=Source(source), destinations=[Destination(path) for path in destinations])
     service.add(plan)
 
+    console.print("The backup plan is added.")