The code is for an app that creates bookmarks. Bookmarks are stored in a sqlite database

Perform a unit test for step #4 of barky.py "Clears the screen and executes the command corresponding to the users choice" based on these 3 modules

Modules are separated by underscores

___________________________barky.py_______________________________

'''

import os

import commands

class Option:

def __init__(self, name, command, prep_call=None):

self.name = name

self.command = command

self.prep_call = prep_call

def choose(self):

data = self.prep_call() if self.prep_call else None

message = self.command.execute(

data) if data else self.command.execute()

print(message)

def __str__(self):

return self.name

def print_options(options):

for shortcut, option in options.items():

print(f'({shortcut}) {option}')

print()

def option_choice_is_valid(choice, options):

return choice in options or choice.upper() in options

def get_option_choice(options):

choice = input('Choose an option: ')

while not option_choice_is_valid(choice, options):

print('Invalid choice')

choice = input('Choose an option: ')

return options[choice.upper()]

def get_user_input(label, required=True):

value = input(f'{label}: ') or None

while required and not value:

value = input(f'{label}: ') or None

return value

def get_new_bookmark_data():

return {

'title': get_user_input('Title'),

'url': get_user_input('URL'),

'notes': get_user_input('Notes', required=False),

}

def get_bookmark_id_for_deletion():

return get_user_input('Enter a bookmark ID to delete')

def clear_screen():

clear = 'cls' if os.name == 'nt' else 'clear'

os.system(clear)

def loop():

# All steps for showing and selecting options

# https://www.w3schools.com/python/python_dictionaries.asp

options = {

'A': Option('Add a bookmark', commands.AddBookmarkCommand(), prep_call=get_new_bookmark_data),

'B': Option('List bookmarks by date', commands.ListBookmarksCommand()),

'T': Option('List bookmarks by title', commands.ListBookmarksCommand(order_by='title')),

'D': Option('Delete a bookmark', commands.DeleteBookmarkCommand(), prep_call=get_bookmark_id_for_deletion),

'Q': Option('Quit', commands.QuitCommand()),

}

clear_screen()

print_options(options)

chosen_option = get_option_choice(options)

clear_screen()

chosen_option.choose()

_ = input('Press ENTER to return to menu')

# this ensures that this module runs first

if __name__ == '__main__':

commands.CreateBookmarksTableCommand().execute()

# endless program loop

while True:

loop()

______________________________________________________

________________commands.py___________________________

from datetime import datetime

import sys

from database import DatabaseManager

# module scope

db = DatabaseManager('bookmarks.db')

class CreateBookmarksTableCommand:

def execute(self):

db.create_table('bookmarks', {

'id': 'integer primary key autoincrement',

'title': 'text not null',

'url': 'text not null',

'notes': 'text',

'date_added': 'text not null',

})

class AddBookmarkCommand:

def execute(self, data):

data['date_added'] = datetime.utcnow().isoformat()

db.add('bookmarks', data)

return 'Bookmark added!'

class ListBookmarksCommand:

def __init__(self, order_by='date_added'):

self.order_by = order_by

def execute(self):

return db.select('bookmarks', order_by=self.order_by).fetchall()

class DeleteBookmarkCommand:

'''

We also need to remove bookmarks.

'''

def execute(self, data):

db.delete('bookmarks', {'id': data})

return 'Bookmark deleted!'

class QuitCommand:

def execute(self):

sys.exit()

__________________________________________

________database.py________________________

import sqlite3

class DatabaseManager:

def __init__(self, database_filename) -> None:

self.connection = sqlite3.connect(database_filename)

def __del__(self):

self.connection.close()

def _execute(self, statement, values=None):

with self.connection:

cursor = self.connection.cursor()

cursor.execute(statement, values or [])

return cursor

def create_table(self, table_name, columns):

columns_with_types = [

f'{column_name} {data_type}'

for column_name, data_type in columns.items() #this loop reads all column information

]

self._execute(

f'''

CREATE TABLE IF NOT EXISTS {table_name}

({','.join(columns_with_types)});

'''

)

def add(self, table_name, data):

placeholders = ', '.join('?' * len(data))

column_names = ', '.join(data.keys())

column_values = tuple(data.values())

self._execute(

f'''

INSERT INTO {table_name}

({column_names})

VALUES ({placeholders});

''',

column_values,

)

def delete(self, table_name, criteria):

placeholders = [f'{column} = ?' for column in criteria.keys()]

delete_criteria = ' AND '.join(placeholders)

self._execute(

f'''

DELETE FROM {table_name}

WHERE {delete_criteria};

''',

tuple(criteria.values())

)

def select(self, table_name, criteria=None, order_by=None):

criteria = criteria or {}

query = f'SELECT * FROM {table_name}'

if criteria:

placeholders = [f'{column} = ?' for column in criteria.keys()]

select_criteria = ' AND '.join(placeholders)

query += f' WHERE {select_criteria}'

if order_by:

query += f' ORDER BY {order_by}'

return self._execute(

query,

tuple(criteria.values()),

)