Coverage reporting in Django - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

Understanding coverage report output in Django tests

You run Django tests with coverage enabled. The coverage report shows 85% coverage for your app. What does this 85% mean?

A 85% of your app's database queries were tested.

B 85% of your test cases passed successfully.

C 85% of your Python code lines in the app were executed during tests.

D 85% of your app's HTML templates were rendered during tests.

💡 Hint

Think about what coverage tools measure: code execution, not test success or database queries.

Coverage percentage shows how many lines of your Python code ran during tests. It does not measure test success or database queries.

📝 Syntax

intermediate

Correct command to run Django tests with coverage

Which command correctly runs Django tests with coverage and generates an HTML report?

A coverage run manage.py test && coverage html

B python coverage run test manage.py && coverage html

C coverage test manage.py && coverage html

D python manage.py coverage test && coverage report

💡 Hint

Remember the order: coverage run runs a command, then coverage html generates the report.

The correct syntax is coverage run manage.py test to run tests with coverage, then coverage html to create the HTML report.

🔧 Debug

advanced

Why does coverage report show 0% after running Django tests?

You ran coverage run manage.py test but the coverage report shows 0% coverage. What is the most likely cause?

A Your tests passed too quickly for coverage to record data.

B Your tests did not import any code from your app.

C You forgot to install the coverage package.

D You ran tests without the coverage tool actually monitoring the code execution.

💡 Hint

Think about how coverage tracks code execution and what happens if it is not properly started.

If coverage is not properly started before running tests, it won't track code execution, resulting in 0% coverage.

❓ state_output

advanced

Interpreting coverage report details

After running coverage on your Django app, the report shows:

Name                  Stmts   Miss  Cover
-----------------------------------------
myapp/views.py           50     10    80%
myapp/models.py          30      0   100%
myapp/forms.py           20      5    75%

How many lines of code were missed in total?

A 15 lines missed

B 5 lines missed

C 10 lines missed

D 0 lines missed

💡 Hint

Add the missed lines from each file.

Missed lines are 10 + 0 + 5 = 15 total missed lines.

🧠 Conceptual

expert

Why exclude migrations from coverage reports in Django?

Why is it common to exclude migration files from coverage reports in Django projects?

A Because migrations are always 100% covered by default.

B Because migration files are auto-generated and not part of the app's logic to test.

C Because migrations run only in production, not during tests.

D Because coverage tools cannot read migration files.

💡 Hint

Think about what migrations are and why testing them is usually unnecessary.

Migrations are generated by Django to change the database schema. They are not hand-written logic and usually don't need coverage measurement.