Coverage reporting in Flask - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

Understanding coverage report output in Flask testing

You run tests on a Flask app with coverage enabled. The coverage report shows 85% for a specific module. What does this mean?

A 85% of the code lines in that module were executed during tests

B 85% of the functions in that module have no bugs

C 85% of the tests passed successfully for that module

D 85% of the module's code is optimized for performance

💡 Hint

Think about what coverage measures: code execution during tests.

Coverage percentage shows how many lines of code were run during tests. 85% means some lines were not tested.

📝 Syntax

intermediate

Correct command to run coverage for Flask tests

Which command correctly runs Flask tests with coverage reporting using the coverage.py tool?

A coverage run -m pytest tests/

B pytest --coverage tests/

C flask coverage run tests/

D coverage test run tests/

💡 Hint

Remember the syntax for running coverage with pytest.

The correct command is coverage run -m pytest tests/ which runs tests under coverage measurement.

🔧 Debug

advanced

Why does coverage report show 0% for a Flask route?

You wrote a test that calls a Flask route, but coverage shows 0% for that route's code. What is the most likely cause?

A The test calls the route but coverage is not measuring subprocesses

B The route code has a syntax error preventing execution

C Coverage only measures database queries, not route code

D The test does not actually call the route function

💡 Hint

Think about whether the route function is really executed during the test.

If the test does not call the route function, coverage will show 0% because the code never runs.

❓ state_output

advanced

Interpreting coverage HTML report results

After running coverage and generating an HTML report, you see some lines highlighted in red. What does this indicate?

A These lines are optimized and run faster

B These lines contain syntax errors

C These lines were not executed during tests

D These lines are deprecated and should be removed

💡 Hint

Colors in coverage reports show which lines ran or not.

Red lines in coverage HTML reports mean those lines were not run during tests, so they lack coverage.

🧠 Conceptual

expert

Why use coverage reporting in Flask projects?

What is the main benefit of using coverage reporting when testing a Flask application?

A It automatically fixes bugs found in the Flask app

B It shows which parts of the code are tested, helping improve test completeness

C It speeds up the Flask app by optimizing code paths

D It replaces the need for writing unit tests

💡 Hint

Think about what coverage helps developers understand about their tests.

Coverage helps identify untested code so developers can write tests to cover those parts, improving reliability.