Python Datatypes (a.k.a. "Groceries") Exercise

Further Exploration Challenges

If you were able to implement the basic requirements with relative ease, or if you are interested in a challenge, consider expanding the scope to include one or more of the challenges below.

Automated Tests

Prerequisites: The pytest Package

Before we test some of the program's logic, we need to abstract that logic into one or more custom functions (e.g. to_usd()) which we can test in isolation. And we'll need to update the organizational structure of our script to include the infamous if __name__ == "__main__" convention, to prevent the rest of the script's functionality from being executed when we attempt to import and test the to_usd() function in isolation.

After making these organizational adjustments to your "groceries.py" file, add another file called "groceries_test.py" and place inside the following contents:

# groceries_test.py

from groceries import to_usd

def test_to_usd():
    # it should apply USD formatting:
    assert to_usd(4.50) == "$4.50"

    # it should display two decimal places:
    assert to_usd(4.5) == "$4.50"

    # it should round to two places:
    assert to_usd(4.55555) == "$4.56"

    # it should display thousands separators:
    assert to_usd(1234567890.5555555) == "$1,234,567,890.56"

Then use the pytest package to run the test:

pytest groceries_test.py

If tests fail, update the logic of the to_usd() function in the "groceries.py" file until the tests pass.

Nice, you're testing like a Pro!