Summary  
This chapter covers the implementation and manipulation of two-dimensional grid data structures, detailing how to create, index, iterate over, and update grid elements.

General domain of usage  
Game development

import unittest
import re
from io import StringIO
from contextlib import redirect_stdout
import importlib

def _dynamic_test(test_case, condition, success_message, failure_message):
    if condition:
        test_case._testMethodName = success_message
        test_case.assertTrue(True, success_message)
    else:
        test_case._testMethodName = failure_message
        test_case.fail(failure_message)

class TestUserCode(unittest.TestCase):

    def test_first_print_outputs_greeting(self):
        # Capture the output of the user code execution.
        import user_code  # The user's solution file should be named "user_code.py".
        f = StringIO()
        with redirect_stdout(f):
            importlib.reload(user_code)
        output = f.getvalue().strip()
        lines = output.splitlines()

        condition = (len(lines) >= 1 and
                     lines[0].strip().lower() == "welcome to the grocery".lower())
        _dynamic_test(
            self,
            condition,
            "The first print line correctly outputs 'Welcome to the Grocery'.",
            "Expected the first line to print 'Welcome to the Grocery' (case insensitive) but got: '{}'".format(
                lines[0] if len(lines) >= 1 else ""
            )
        )

    def test_second_print_outputs_store(self):
        # Capture the output of the user code execution.
        import user_code  # The user's solution file should be named "user_code.py".
        f = StringIO()
        with redirect_stdout(f):
            importlib.reload(user_code)
        output = f.getvalue().strip()
        lines = output.splitlines()

        condition = (len(lines) >= 2 and
                     lines[1].strip().lower() == "store".lower())
        _dynamic_test(
            self,
            condition,
            "The second print line correctly outputs 'Store'.",
            "Expected the second line to print 'Store' (case insensitive) but got: '{}'".format(
                lines[1] if len(lines) >= 2 else ""
            )
        )

if __name__ == '__main__':
    unittest.main()


test_main.py

Python is a high-level, interpreted, general-purpose programming
language. Distinguished from languages such as HTML, CSS, and JavaScript, which are mainly
utilized in web development, Python boasts versatility across multiple domains, including
software development, data science, and back-end development. This course will guide you
through Python's fundamental concepts, equipping you with the skills to create your own
functions by the conclusion of the program.

In this section, you will explore the fundamentals of Python, get acquainted
with your workspace, perform simple math operations, and display your findings.

GRID

Solution