Summary  
This chapter covers how to perform basic arithmetic operations—addition, subtraction, multiplication, and division—in Python using printing in code.

General domain of usage  
Grocery cost calculations

Pythonは、数学演算を簡単かつ強力に行うことができます。以下の基本的な算術演算子を使用します。

- **加算** (`+`)
- **減算** (`-`)
- **乗算** (`*`)
- **除算** (`/`)

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


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_addition_operation_result_is_correct(self):
        # Test the first printed value: 5.42 + 4.39 should equal 9.81.
        import user_code
        output_capture = StringIO()
        with redirect_stdout(output_capture):
            importlib.reload(user_code)
        output = output_capture.getvalue().strip()
        lines = output.splitlines()

        if len(lines) < 1:
            _dynamic_test(self, False, "", "Missing addition result.")

        addition_result = lines[0].strip()
        expected_addition = str(5.42 + 4.39)
        condition = addition_result == expected_addition

        _dynamic_test(
            self,
            condition,
            "Addition result is correct.",
            f"Expected addition result to be '{expected_addition}' but got '{addition_result}'."
        )

    def test_subtraction_operation_result_is_correct(self):
        # Test the second printed value: 12.30 - 5.50 should equal 6.8.
        import user_code
        output_capture = StringIO()
        with redirect_stdout(output_capture):
            importlib.reload(user_code)
        output = output_capture.getvalue().strip()
        lines = output.splitlines()

        if len(lines) < 2:
            _dynamic_test(self, False, "", "Missing subtraction result.")

        subtraction_result = lines[1].strip()
        expected_subtraction = str(12.30 - 5.50)
        condition = subtraction_result == expected_subtraction

        _dynamic_test(
            self,
            condition,
            "Subtraction result is correct.",
            f"Expected subtraction result to be '{expected_subtraction}' but got '{subtraction_result}'."
        )

    def test_multiplication_operation_result_is_correct(self):
        # Test the third printed value: 7.32 * 0.2 should equal 1.464.
        import user_code
        output_capture = StringIO()
        with redirect_stdout(output_capture):
            importlib.reload(user_code)
        output = output_capture.getvalue().strip()
        lines = output.splitlines()

        if len(lines) < 3:
            _dynamic_test(self, False, "", "Missing multiplication result.")

        multiplication_result = lines[2].strip()
        expected_multiplication = str(7.32 * 0.2)
        condition = multiplication_result == expected_multiplication

        _dynamic_test(
            self,
            condition,
            "Multiplication result is correct.",
            f"Expected multiplication result to be '{expected_multiplication}' but got '{multiplication_result}'."
        )

    def test_division_operation_result_is_correct(self):
        # Test the fourth printed value: 8.30 / 20 should equal 0.415.
        import user_code
        output_capture = StringIO()
        with redirect_stdout(output_capture):
            importlib.reload(user_code)
        output = output_capture.getvalue().strip()
        lines = output.splitlines()

        if len(lines) < 4:
            _dynamic_test(self, False, "", "Missing division result.")

        division_result = lines[3].strip()
        expected_division = str(8.30 / 20)
        condition = division_result == expected_division

        _dynamic_test(
            self,
            condition,
            "Division result is correct.",
            f"Expected division result to be '{expected_division}' but got '{division_result}'."
        )


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


test_main.py

データ分析のためのPythonの基礎をしっかりと身につけます。変数、データ型、文字列、条件文、ループ、主要なデータ構造、関数について、分析作業に関連する例を用いて学習します。

Simple Arithmetics

解答