Coverage thresholds in PyTest - Test Execution Trace

Test Overview

This test runs pytest with coverage measurement and verifies that the code coverage meets the minimum threshold set in the configuration. It ensures that the tested code is sufficiently covered by tests.

Test Code - PyTest

PyTest

import subprocess
import sys

def test_coverage_threshold():
    # Run pytest with coverage and fail if coverage is below threshold
    result = subprocess.run([
        sys.executable, "-m", "pytest", "--cov=src", "--cov-fail-under=80"
    ], capture_output=True, text=True)
    # Check that pytest exited with code 0 (success)
    assert result.returncode == 0, f"Coverage threshold not met:\n{result.stdout}\n{result.stderr}"

Execution Trace - 4 Steps

Step	Action	System State	Assertion	Result
1	Test starts by running pytest with coverage options and threshold set to 80%	Terminal ready to execute pytest command	-	PASS
2	Subprocess runs pytest with --cov=src and --cov-fail-under=80	Pytest runs tests and measures coverage on 'src' folder	-	PASS
3	Pytest finishes and returns exit code	Coverage report generated, exit code indicates pass/fail	Check if return code is 0 (coverage >= 80%)	PASS
4	Assert that coverage threshold is met	Test framework receives assertion result	Assert result.returncode == 0	PASS

Failure Scenario

Failing Condition: Code coverage is below 80%, causing pytest to exit with non-zero code

Execution Trace Quiz - 3 Questions

What does the test check after running pytest with coverage?

A That all tests passed regardless of coverage

B That the coverage percentage is at least 80%

C That the source code has no syntax errors

D That pytest ran without any warnings

Key Result

Using coverage thresholds in automated tests helps ensure your code is well tested and prevents lowering test quality over time.