pytest-cov for coverage - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to run pytest with coverage reporting.

PyTest

pytest --cov=[1]

Drag options to blanks, or click blank then click option'

Amy_module

Btests

Csetup.py

DREADME.md

Attempts:

3 left

💡 Hint

Common Mistakes

Using the test folder name instead of the module name.

Trying to measure coverage on non-Python files.

The --cov option specifies the module or package to measure coverage for. Here, my_module is the code being tested.

2fill in blank

medium

Complete the command to generate a coverage report in the terminal.

PyTest

pytest --cov=my_module --cov-report=[1]

Drag options to blanks, or click blank then click option'

Ahtml

Bterm

Cxml

Djson

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'html' when expecting terminal output.

Using 'xml' or 'json' which generate files instead.

The term option shows the coverage report directly in the terminal after tests run.

3fill in blank

hard

Fix the error in the command to generate an HTML coverage report.

PyTest

pytest --cov=my_module --cov-report=[1]

Drag options to blanks, or click blank then click option'

Ajson

Bxml

Cterm

Dhtml

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'term' which only shows output in the terminal.

Using 'xml' or 'json' which create different file formats.

The html option generates a detailed coverage report as HTML files you can open in a browser.

4fill in blank

hard

Fill both blanks to run pytest with coverage for app and generate both terminal and XML reports.

PyTest

pytest --cov=[1] --cov-report=[2] --cov-report=xml

Drag options to blanks, or click blank then click option'

Aapp

Bterm

Chtml

Djson

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'html' instead of 'term' for terminal output.

Using a wrong module name.

Specify the module app for coverage and use term to show the report in the terminal, plus xml for an XML file.

5fill in blank

hard

Fill all three blanks to run pytest with coverage for service, generate an HTML report, and fail if coverage is below 80%.

PyTest

pytest --cov=[1] --cov-report=[2] --cov-fail-under=[3]

Drag options to blanks, or click blank then click option'

Aservice

Bhtml

C80

Dterm

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'term' instead of 'html' for the report.

Setting the fail-under value too high or too low.

Using the wrong module name.

Use service as the module, html for the report format, and 80 to set the minimum coverage percentage required to pass.

Practice

1. What is the main purpose of using pytest-cov in your testing workflow?

easy

A. To generate test data automatically

B. To speed up test execution time

C. To automatically fix failing tests

D. To measure how much of your code is covered by tests

Solution

1. Step 1: Understand pytest-cov functionality

   pytest-cov is a plugin that measures code coverage during test runs.

2. Step 2: Identify the main goal of coverage tools

   Coverage tools show which parts of code are tested and which are not.

3. Final Answer:

   To measure how much of your code is covered by tests -> Option D

4. Quick Check:

   pytest-cov = code coverage measurement [OK]

Hint: Coverage means how much code tests run over [OK]

Common Mistakes:

• Confusing coverage with test speed
• Thinking pytest-cov fixes tests automatically
• Assuming pytest-cov generates test data

2. Which command correctly runs pytest with coverage for a package named myapp?

easy

A. pytest -cov myapp

B. pytest --cov=myapp

C. pytest --coverage myapp

D. pytest --cov tests/

Solution

1. Step 1: Recall correct pytest-cov syntax

   The correct option to enable coverage is --cov=package_name.

2. Step 2: Compare options

   pytest --cov=myapp uses --cov=myapp, which is the correct syntax. pytest --cov tests/ would incorrectly target the tests directory instead of the myapp package.

3. Final Answer:

   pytest --cov=myapp -> Option B

4. Quick Check:

   Use --cov=package [OK]

Hint: Use equal sign with --cov like --cov=package [OK]

Common Mistakes:

• Targeting tests directory instead of the package
• Using -cov instead of --cov
• Using --coverage instead of --cov

3. Given this command run:
pytest --cov=myapp tests/test_module.py
What output will you expect related to coverage?

medium

A. A report showing coverage percentage for myapp package

B. A list of all tests run without coverage info

C. An error saying coverage option is invalid

D. Coverage report for tests directory only

Solution

1. Step 1: Understand coverage target

   The --cov=myapp option measures coverage for the myapp package, not tests.

2. Step 2: Predict output

   Running tests in tests/test_module.py with coverage enabled will show coverage report for myapp code exercised by those tests.

3. Final Answer:

   A report showing coverage percentage for myapp package -> Option A

4. Quick Check:

   --cov=package shows coverage for that package [OK]

Hint: Coverage reports show tested code, not test files [OK]

Common Mistakes:

• Expecting coverage for test files instead of source code
• Thinking coverage option causes errors
• Confusing coverage report with test list output

4. You ran pytest --cov=myapp but no coverage report appeared. What is the most likely cause?

medium

A. You forgot to install pytest-cov plugin

B. You ran pytest without any test files

C. Your code has no functions to cover

D. You used wrong package name in --cov option

Solution

1. Step 1: Check plugin installation

   pytest-cov must be installed to enable coverage reporting.

2. Step 2: Understand symptoms

   If no coverage report appears, the plugin is likely missing or not activated.

3. Final Answer:

   You forgot to install pytest-cov plugin -> Option A

4. Quick Check:

   pytest-cov missing = no coverage report [OK]

Hint: Install pytest-cov to get coverage reports [OK]

Common Mistakes:

• Assuming coverage works without plugin installed
• Thinking coverage depends on code content
• Ignoring plugin installation errors

5. You want to generate an HTML coverage report for your package app using pytest-cov. Which command should you run?

hard

A. pytest --coverage=app --report=html

B. pytest --cov=app --html=coverage

C. pytest --cov=app --cov-report=html

D. pytest --cov app --html-report

Solution

1. Step 1: Recall pytest-cov report syntax

   The option --cov-report=html generates an HTML coverage report.

2. Step 2: Match correct command format

   pytest --cov=app --cov-report=html correctly uses --cov=app and --cov-report=html together.

3. Final Answer:

   pytest --cov=app --cov-report=html -> Option C

4. Quick Check:

   Use --cov-report=html for HTML coverage [OK]

Hint: Use --cov-report=html to get HTML coverage output [OK]

Common Mistakes:

• Using --html instead of --cov-report=html
• Omitting equal signs in options
• Confusing coverage options with test report options