Python Testing with pytest

Isolating the Command-Line Interface

The Cards CLI uses the Typer library^[35] to handle all of the command-line parts, and then it passes the real logic off to the Cards API. In testing the Cards CLI, the idea is that we’d like to test the code within cli.py and cut off access to the rest of the system. To do that, we have to look at cli.py to see how it’s accessing the rest of Cards.

The cli.py module accesses the rest of the Cards system through an import of cards:

cards_proj/src/cards/cli.py

import cards

Through this cards namespace, cli.py accesses:

• cards.__version__ (a string)
• cards.CardDB (a class representing the main API methods)
• cards.InvalidCardID (an exception)
• cards.Card (the primary data type for use between the CLI and API)

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