pytest-cov for coverage - Test Execution Trace

Test Overview

This test runs a simple function and uses pytest-cov to check how much of the code is covered by the test. It verifies that the coverage report shows 100% coverage for the tested function.

Test Code - pytest

PyTest

import pytest

def add(a, b):
    return a + b

def test_add():
    assert add(2, 3) == 5

# To run coverage: pytest --cov=./ --cov-report=term-missing

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	Test starts by running pytest with coverage plugin enabled	Terminal ready to run pytest command	-	PASS
2	pytest discovers test_add function in test file	pytest test collection complete	-	PASS
3	pytest runs test_add which calls add(2, 3)	Function add executes and returns 5	assert add(2, 3) == 5	PASS
4	pytest-cov collects coverage data during test run	Coverage data recorded for add function	-	PASS
5	pytest finishes and prints coverage report showing 100% coverage for add function	Terminal displays coverage summary with no missing lines	Coverage report shows 100% coverage	PASS

Failure Scenario

Failing Condition: Test fails if add function returns wrong result or coverage is incomplete

Execution Trace Quiz - 3 Questions

What does pytest-cov do during the test run?

A It records which lines of code were executed

B It runs tests faster

C It changes the test results

D It skips tests without coverage

Key Result

Using pytest-cov helps you see exactly which parts of your code are tested, so you can improve your tests and avoid missing important cases.