Branch coverage in Testing Fundamentals - Test Execution Trace

Test Overview

This test checks if all possible branches (true and false paths) in a simple decision are executed. It verifies that the code correctly handles both conditions.

Test Code - PyTest

Testing Fundamentals

def is_even(num):
    if num % 2 == 0:
        return True
    else:
        return False


def test_is_even():
    assert is_even(4) == True  # Tests the 'true' branch
    assert is_even(5) == False # Tests the 'false' branch

if __name__ == '__main__':
    test_is_even()

Execution Trace - 6 Steps

Step	Action	System State	Assertion	Result
1	Test starts	Test environment is ready with the is_even function loaded	-	PASS
2	Calls is_even(4)	Function receives input 4	Checks if 4 % 2 == 0 evaluates to True	PASS
3	Returns True for input 4	Function returns True	Assert that returned value is True	PASS
4	Calls is_even(5)	Function receives input 5	Checks if 5 % 2 == 0 evaluates to False	PASS
5	Returns False for input 5	Function returns False	Assert that returned value is False	PASS
6	Test ends	All assertions passed, both branches covered	Branch coverage achieved for both true and false paths	PASS

Failure Scenario

Failing Condition: If the function always returns True or always returns False, missing one branch

Execution Trace Quiz - 3 Questions

What does branch coverage ensure in this test?

A Only the false path of the if statement is tested

B Only the true path of the if statement is tested

C Both true and false paths of the if statement are tested

D The function is tested with random inputs

Key Result

Branch coverage testing ensures that every possible decision path in the code is executed at least once, helping catch errors in all conditions.