Coverage thresholds in PyTest - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to run pytest with coverage and fail if coverage is below 80%.

PyTest

pytest --cov=my_package --cov-fail-under=[1]

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

A100

B70

C90

D80

Attempts:

3 left

💡 Hint

Common Mistakes

Using a value lower than 80 which allows lower coverage.

Using 100 which is too strict for many projects.

The option '--cov-fail-under=80' makes pytest fail if coverage is below 80%.

2fill in blank

medium

Complete the pytest command to measure coverage for the 'utils' module only.

PyTest

pytest --cov=[1] --cov-fail-under=75

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

Autils

Btests

Cmain

Dsetup

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'tests' which measures test files, not source code.

Using 'setup' which is unrelated here.

The '--cov=utils' option measures coverage only for the 'utils' module.

3fill in blank

hard

Fix the error in the pytest coverage command to correctly fail if coverage is below 85%.

PyTest

pytest --cov=myapp --cov-fail-under=[1]

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

A85

B95

Cfail-under=85

D75

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'fail-under=85' as a value which is invalid.

Setting the threshold too low or too high.

The correct syntax is '--cov-fail-under=85' to fail if coverage is below 85%.

4fill in blank

hard

Fill both blanks to create a pytest command that measures coverage for 'app' and fails if coverage is below 90%.

PyTest

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

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

Aapp

B80

C90

Dtests

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'tests' instead of 'app' for coverage.

Setting threshold to 80 instead of 90.

Use '--cov=app' to measure 'app' module and '--cov-fail-under=90' to set 90% threshold.

5fill in blank

hard

Fill all three blanks to create a pytest command that measures coverage for 'service', fails if coverage is below 85%, and outputs a coverage report in XML format.

PyTest

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

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

Aservice

B85

Cxml

Dhtml

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'html' instead of 'xml' for report format.

Setting threshold incorrectly.

Use '--cov=service' for the module, '--cov-fail-under=85' for threshold, and '--cov-report=xml' for XML report.

Practice

1. What does setting a coverage threshold in pytest ensure?

easy

A. Only tests with coverage above 90% are executed

B. Tests run faster by skipping some checks

C. The test run fails if coverage is below a set percentage

D. Coverage reports are hidden from the user

Solution

1. Step 1: Understand coverage threshold purpose

   Coverage thresholds set a minimum coverage percentage to maintain test quality.

2. Step 2: Effect of coverage below threshold

   If coverage is below the threshold, pytest fails the test run to alert missing tests.

3. Final Answer:

   The test run fails if coverage is below a set percentage -> Option C

4. Quick Check:

   Coverage threshold = fail if below limit [OK]

Hint: Coverage threshold means minimum coverage to pass tests [OK]

Common Mistakes:

• Thinking threshold speeds up tests
• Believing threshold skips tests
• Assuming threshold hides reports

2. Which is the correct pytest command to set a coverage fail threshold at 80%?

easy

A. pytest --cov-fail-under=80

B. pytest --fail-under-cov=80

C. pytest --coverage-threshold=80

D. pytest --fail-coverage=80

Solution

1. Step 1: Recall pytest coverage threshold syntax

   The correct option uses --cov-fail-under to set minimum coverage.

2. Step 2: Match the correct command

   pytest --cov-fail-under=80 matches the exact pytest CLI option for coverage fail threshold.

3. Final Answer:

   pytest --cov-fail-under=80 -> Option A

4. Quick Check:

   Correct CLI option = --cov-fail-under [OK]

Hint: Use --cov-fail-under to set coverage threshold [OK]

Common Mistakes:

• Mixing option order or names
• Using non-existent flags
• Confusing coverage threshold with other options

3. Given this pytest command:
pytest --cov=myapp --cov-fail-under=90
and coverage report shows 85%, what will happen?

medium

A. Tests pass but with a warning

B. Tests fail due to coverage below 90%

C. Tests run without coverage check

D. Coverage report is not generated

Solution

1. Step 1: Understand the coverage threshold set

   The command sets a fail threshold at 90% coverage.

2. Step 2: Compare actual coverage with threshold

   Actual coverage is 85%, which is below 90%, so pytest fails the test run.

3. Final Answer:

   Tests fail due to coverage below 90% -> Option B

4. Quick Check:

   Coverage 85% < 90% threshold = fail [OK]

Hint: Coverage below threshold causes test failure [OK]

Common Mistakes:

• Assuming tests pass with warning
• Thinking coverage check is skipped
• Believing report is not generated

4. You set --cov-fail-under=75 but pytest does not fail even when coverage is 70%. What is the likely cause?

medium

A. You must use --fail-under-cov instead

B. Threshold value must be above 80%

C. Coverage is always ignored in pytest

D. Coverage plugin is not installed or enabled

Solution

1. Step 1: Check coverage plugin status

   If coverage plugin is missing or disabled, threshold has no effect.

2. Step 2: Understand threshold behavior

   Threshold works only if coverage plugin runs and measures coverage.

3. Final Answer:

   Coverage plugin is not installed or enabled -> Option D

4. Quick Check:

   Missing plugin = threshold ignored [OK]

Hint: Ensure coverage plugin is active for thresholds to work [OK]

Common Mistakes:

• Thinking threshold values have minimum limits
• Believing coverage is ignored by default
• Using wrong command option names

5. You want to enforce different coverage thresholds for branches and statements: 80% for branches and 90% for statements. Which pytest configuration snippet achieves this?

hard

A. [run]\nbranch = True\n[report]\nfail_under = 90\nfail_under_branch = 80

B. [run]\nbranch = True\n[report]\nfail_under = 80\nfail_under_branch = 90

C. [coverage]\nbranch = True\nthresholds = statements:90, branches:80

D. [coverage]\nfail_under_statements = 90\nfail_under_branches = 80

Solution

1. Step 1: Enable branch coverage in config

   Set branch = True under [run] to measure branch coverage.

2. Step 2: Set fail thresholds correctly

   Under [report], fail_under sets statement threshold, fail_under_branch sets branch threshold.

3. Final Answer:

   [run]\nbranch = True\n[report]\nfail_under = 90\nfail_under_branch = 80 -> Option A

4. Quick Check:

   Branch coverage enabled + correct thresholds = [run]\nbranch = True\n[report]\nfail_under = 90\nfail_under_branch = 80 [OK]

Hint: Use [run] branch=True and [report] fail_under_branch for branches [OK]

Common Mistakes:

• Swapping statement and branch thresholds
• Using wrong config section names
• Missing branch = True setting