pytest-cov setup - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Purpose of pytest-cov in testing

What is the main purpose of using pytest-cov in a Python testing environment?

A To measure how much of the code is executed during tests

B To automatically fix bugs found during tests

C To speed up test execution by parallelizing tests

D To generate test data for parameterized tests

💡 Hint

Think about what 'cov' in pytest-cov might stand for.

pytest-cov is a plugin that measures code coverage, showing which parts of the code were run during tests.

❓ Predict Output

intermediate

Output of pytest-cov command

What output will you see after running this command?

pytest --cov=my_module tests/

Assume my_module has 100 lines, and tests cover 80 lines.

A A list of all tests run without coverage information

B An error saying <code>--cov</code> is an unknown option

C A coverage report showing 80% coverage of <code>my_module</code>

D A coverage report showing 100% coverage of <code>my_module</code>

💡 Hint

Think about what coverage means and what the command requests.

The command runs tests and shows coverage for my_module. Since only 80 lines are covered, the report shows 80% coverage.

❓ locator

advanced

Correct pytest-cov configuration in pytest.ini

Which pytest.ini configuration correctly enables coverage reporting for the app package and generates an XML report?

A

[pytest]
addopts = --cov app --cov-report xml

B

[pytest]
addopts = --cov=app --cov-report=xml

C

[pytest]
addopts = --coverage=app --coverage-report=xml

D

[pytest]
coverage = app
coverage_report = xml

💡 Hint

Check the exact option names for pytest-cov.

The correct options are --cov=app and --cov-report=xml. Other options are invalid or incorrectly formatted.

❓ assertion

advanced

Valid assertion for coverage percentage in pytest-cov report

Which assertion correctly checks that the coverage percentage is at least 90% in a pytest-cov generated report stored as a variable coverage_percent?

A assert coverage_percent < 90

B assert coverage_percent > 90

C assert coverage_percent == 90

D assert coverage_percent >= 90

💡 Hint

Think about including 90% as acceptable coverage.

Using >= 90 ensures coverage is at least 90%, including exactly 90%. Other options exclude 90% or check wrong conditions.

🔧 Debug

expert

Identify the cause of missing coverage report

You ran pytest --cov=myapp tests/ but no coverage report is generated. Which is the most likely cause?

A The <code>pytest-cov</code> plugin is not installed

B The tests folder is empty

C The <code>myapp</code> folder has no Python files

D The <code>pytest.ini</code> file is missing

💡 Hint

Think about what enables coverage reporting in pytest.

If pytest-cov is not installed, pytest does not recognize --cov and no coverage report is generated. Other options do not prevent coverage report generation if tests run.