Coverage thresholds in PyTest - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a coverage threshold in testing?

A coverage threshold is a set minimum percentage of code that must be tested. If tests cover less than this, the test run fails.

beginner

How do you set a coverage threshold in pytest?

You set it using the --cov-fail-under option followed by a number, like --cov-fail-under=80 to require at least 80% coverage.

beginner

Why use coverage thresholds?

Coverage thresholds help keep tests thorough. They stop code from being accepted if tests don't cover enough, improving quality.

beginner

What happens if coverage is below the threshold in pytest?

The test run fails and pytest returns a non-zero exit code. This alerts you to add more tests.

intermediate

Can coverage thresholds be set for specific parts of code?

Yes, you can set thresholds for the whole project or for specific files or directories using configuration files like .coveragerc.

What does the pytest option --cov-fail-under=90 do?

A Fails tests if coverage is below 90%

B Sets coverage to exactly 90%

C Ignores coverage below 90%

D Runs tests only on 90% of code

The option --cov-fail-under=90 makes pytest fail the test run if coverage is less than 90%.

Why is setting a coverage threshold useful?

A To skip tests

B To speed up tests

C To reduce code size

D To ensure tests cover enough code

Coverage thresholds ensure tests cover enough code to catch bugs and maintain quality.

If coverage is 75% but threshold is 80%, what happens?

A Test run passes

B Test run fails

C Coverage is ignored

D Tests rerun automatically

If coverage is below the threshold, pytest fails the test run to signal insufficient testing.

Can coverage thresholds be set per file in pytest?

A Yes, using configuration files

B No, only global thresholds

C Only for test files

D Only for Python 2

Pytest allows setting coverage thresholds per file or directory via configuration files like .coveragerc.

What exit code does pytest return if coverage threshold is not met?

A Zero exit code

B Exit code 100

C Non-zero exit code

D No exit code

Pytest returns a non-zero exit code to indicate failure when coverage thresholds are not met.

Explain how to enforce a minimum coverage percentage using pytest.

Think about the command line option that sets the minimum coverage.

Describe why coverage thresholds improve software quality.

Consider the role of tests in catching problems.