Single parameter in PyTest - Test Execution Trace

Test Overview

This test checks if a function correctly doubles a single input number. It verifies the output matches the expected doubled value.

Test Code - pytest

PyTest

import pytest

def double(x):
    return x * 2

@pytest.mark.parametrize('input_value, expected', [
    (2, 4),
    (5, 10),
    (0, 0),
    (-3, -6)
])
def test_double(input_value, expected):
    result = double(input_value)
    assert result == expected, f"Expected {expected} but got {result}"

Execution Trace - 7 Steps

Step	Action	System State	Assertion	Result
1	Test starts	pytest test runner initialized	-	PASS
2	pytest collects test_double with 4 parameter sets	Test cases ready to run with inputs (2,4), (5,10), (0,0), (-3,-6)	-	PASS
3	Runs test_double with input_value=2, expected=4	Function double called with 2	Check if double(2) == 4	PASS
4	Runs test_double with input_value=5, expected=10	Function double called with 5	Check if double(5) == 10	PASS
5	Runs test_double with input_value=0, expected=0	Function double called with 0	Check if double(0) == 0	PASS
6	Runs test_double with input_value=-3, expected=-6	Function double called with -3	Check if double(-3) == -6	PASS
7	All parameterized tests completed	All assertions passed	-	PASS

Failure Scenario

Failing Condition: The double function returns incorrect value for any input

Execution Trace Quiz - 3 Questions

What does the test_double function verify?

A That the double function returns input squared

B That the double function returns input plus 2

C That the double function returns input multiplied by 2

D That the double function returns input divided by 2

Key Result

Using parameterized tests helps check multiple input cases efficiently with one test function.