Python unit test: Accurate floating-point calculation handling

Last update on December 21 2024 07:48:51 (UTC/GMT +8 hours)

Write a Python unit test that checks if a function handles floating-point calculations accurately.

Sample Solution:

Python Code:

# Import the 'unittest' module for writing unit tests.
import unittest

# Define a test case class 'TestFloatingPointCalculations' that inherits from 'unittest.TestCase'.
class TestFloatingPointCalculations(unittest.TestCase):
    # Define a test method 'test_addition' to test floating-point addition.
    def test_addition(self):
        # Perform the addition operation.
        result = 0.3 + 0.5
        # Assert that the result is approximately equal to 0.8 within 6 decimal places.
        self.assertAlmostEqual(result, 0.8, places=6)

    # Define a test method 'test_multiplication' to test floating-point multiplication.
    def test_multiplication(self):
        # Perform the multiplication operation.
        result = 0.3 * 0.5
        # Assert that the result is approximately equal to 0.15 within 6 decimal places.
        self.assertAlmostEqual(result, 0.15, places=6)

    # Define a test method 'test_division' to test floating-point division.
    def test_division(self):
        # Perform the division operation.
        result = 0.7 / 0.3
        # Assert that the result is approximately equal to 2.333333 within 6 decimal places.
        self.assertAlmostEqual(result, 2.333333, places=6)

# Check if the script is run as the main program.
if __name__ == '__main__':
    # Run the test cases using 'unittest.main()'.
    unittest.main()

Sample Output:

Ran 3 tests in 0.001s
OK

Explanation:

In the above exercise,

• TestFloatingPointCalculations class that inherits from unittest.TestCase. Inside the class, there are three test methods: test_addition(), test_multiplication(), and test_division().
• In each test method, we perform a specific floating-point calculation and store the result in the result variable. We then use the self.assertAlmostEqual assertion to check if the result is approximately equal to the expected value with a given number of decimal places.

For example, in the test_addition method, we calculate the sum of 0.3 and 0.5 and compare it to the expected value of 0.8. We use self.assertAlmostEqual(result, 0.8, places=6) to assert that the result is approximately equal to 0.8 with a precision of up to 6 decimal places.

Flowchart:

Previous: Check file existence in a directory.
Next: Multi-threading handling verification.