text: import controllers.controller_category as c
  from utils.exception import ErrorMessage
  
  print(' * Testing: Category...')
  
  # The list of category should be empty
  assert len(c.list_categories()) == 0
  # Addomg a new category
  assert c.add_category('Trending', '6') is None
  # Adding a new category with the same name
  assert c.add_category('trending', '5').get() == 'The category already exists.'
  # Adding a new category with a different name
  assert c.add_category('Milk Tea', '2') is None
  assert c.add_category('Wrong Coffee', '3') is None
  # A new category with the same name
  assert c.add_category('Summer', '3') is None
  # Add additional categories
  assert c.add_category('Fruity', '1') is None
  assert c.add_category('Black & Green', '0') is None
  # Adding a category without name and priorty respectively
  assert c.add_category('', '3').get() == 'Invalid input type.'
  assert c.add_category('New', '').get() =='Invalid input type.'
  
  assert c.list_categories() == [
      {'category_id': 1, 'category_name': 'Trending', 'priority': 6},
      {'category_id': 4, 'category_name': 'Summer', 'priority': 3},
      {'category_id': 3, 'category_name': 'Wrong Coffee', 'priority': 3},
      {'category_id': 2, 'category_name': 'Milk Tea', 'priority': 2},
      {'category_id': 5, 'category_name': 'Fruity', 'priority': 1},
      {'category_id': 6, 'category_name': 'Black & Green', 'priority': 0}
  ]
  
  # Test for update and delete
  assert c.update_category('3', 'Coffee', '4') is None
  assert c.update_category('8', 'Coffee', '4').get() == 'The category does not exists.'
  assert c.add_category('Dummy', '0') is None
  assert c.remove_category('7') is None
  assert c.remove_category('8').get() == 'The category does not exists.'
  
  print(' ✓ Category has passed all the tests')
  