Testing Lab: TDD Calculator Challenge

In Test-Driven Development (TDD), you write tests before you write the implementation. This lab walks you through building a Calculator class using TDD.

Your Task

Implement the Calculator class and its test suite in the same file.

The Calculator class must have:

• add(a, b) — returns a + b
• subtract(a, b) — returns a - b
• multiply(a, b) — returns a * b
• divide(a, b) — returns a / b, raises ZeroDivisionError if b == 0
• power(base, exp) — returns base ** exp
• history — a list of strings recording each operation, e.g. "3 + 4 = 7"
• clear_history() — empties the history list

The TestCalculator class must have at least these test methods:

• test_add — tests addition
• test_subtract — tests subtraction
• test_multiply — tests multiplication
• test_divide — tests normal division
• test_divide_by_zero — tests that divide raises ZeroDivisionError
• test_power — tests exponentiation
• test_history_records_operations — tests that operations are logged in history
• test_clear_history — tests that clear_history() empties history

Running tests

At the bottom of the file, add:

Run with: python solution.py

Example output