In this challenge, you will apply your understanding of Python testing frameworks by implementing and testing a simple calculator class. Your calculator should support four basic operations: addition, subtraction, multiplication, and division. You will use the `unittest` framework to write comprehensive tests that verify the correctness of each operation.

Remember to design your tests so that each calculator method is covered, including checks for normal operation and for edge cases such as division by zero. 


import unittest
import user_code
import ast
import re   
import importlib
import csv
import unittest
import importlib

class TestTask(unittest.TestCase):
    def setUp(self):
        self.user_code = importlib.import_module("user_code")
        importlib.reload(self.user_code)
        self.Calc = getattr(self.user_code, "Calculator", None)

    def test_add_positive_and_negative(self):
        calc = self.Calc()
        _dynamic_test(
            self,
            calc.add(2, 3) == 5 and calc.add(-2, -3) == -5,
            "Add method returns correct sums for positive and negative integers",
            f"Add method failed: got {calc.add(2,3)} for (2,3), {calc.add(-2,-3)} for (-2,-3)",
        )

    def test_subtract_positive_and_negative(self):
        calc = self.Calc()
        _dynamic_test(
            self,
            calc.subtract(5, 3) == 2 and calc.subtract(-2, -3) == 1,
            "Subtract method returns correct results for positive and negative integers",
            f"Subtract method failed: got {calc.subtract(5,3)} for (5,3), {calc.subtract(-2,-3)} for (-2,-3)",
        )

    def test_multiply_positive_and_zero(self):
        calc = self.Calc()
        _dynamic_test(
            self,
            calc.multiply(4, 3) == 12 and calc.multiply(0, 5) == 0,
            "Multiply method returns correct product for positive integers and zero",
            f"Multiply method failed: got {calc.multiply(4,3)} for (4,3), {calc.multiply(0,5)} for (0,5)",
        )

    def test_divide_integer_and_float(self):
        calc = self.Calc()
        _dynamic_test(
            self,
            calc.divide(10, 2) == 5 and calc.divide(7, 2) == 3.5,
            "Divide method returns correct quotient for integer and floating-point division",
            f"Divide method failed: got {calc.divide(10,2)} for (10,2), {calc.divide(7,2)} for (7,2)",
        )

    def test_divide_by_zero(self):
        calc = self.Calc()
        try:
            calc.divide(5, 0)
            _dynamic_test(
                self,
                False,
                "Divide method raises ZeroDivisionError when dividing by zero",
                "Divide method did not raise ZeroDivisionError when dividing by zero",
            )
        except ZeroDivisionError:
            _dynamic_test(
                self,
                True,
                "Divide method raises ZeroDivisionError when dividing by zero",
                "Divide method did not raise ZeroDivisionError when dividing by zero",
            )

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)

def normalize_text(text):
    text = text.lower()
    text = re.sub(r"\\s{2,}", " ", text)
    text = re.sub(r"\\s*([,:?])\\s*", r"\\1 ", text)
    return text.strip()

def change_var(code: str, var_name: str, value: str) -> str:
    tree = ast.parse(code)
    lines = code.splitlines()
    changed = False
    # Collect all assignment nodes to modify
    assign_nodes = [
        (i, node)
        for i, node in enumerate(tree.body)
        if isinstance(node, ast.Assign)
        and any(isinstance(target, ast.Name) and target.id == var_name for target in node.targets)
    ]

    # If nothing to change, return unmodified code
    if not assign_nodes:
        return code

    # Perform replacements for all matching assignments (from last to first to not break line offsets)
    for i, node in reversed(assign_nodes):
        start_line = node.lineno - 1
        line = lines[start_line]
        indent = ' ' * (len(line) - len(line.lstrip()))
        lines[start_line] = f"{indent}{var_name} = {value}"
        next_line = len(lines)
        for next_node in tree.body[i+1:]:
            if hasattr(next_node, 'lineno'):
                next_line = next_node.lineno - 1
                break
        if next_line > start_line + 1:
            lines[start_line+1:next_line] = []
        changed = True

    return '\\n'.join(lines) if changed else code

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


test_main.py

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Explore how to write, organize, and run tests using Python's unittest and pytest frameworks.

Challenge: Test a Calculator Class

Solution