Registering markers in pytest.ini - Build an Automation Script

Verify custom pytest markers are registered and used correctly

Preconditions (2)

Step 1: Open pytest.ini file

Step 2: Add a custom marker named 'slow' with description 'marks tests as slow'

Step 3: Create a test file test_sample.py

Step 4: Add two test functions: one marked with @pytest.mark.slow and one without any marker

Step 5: Run pytest with the option '-m slow' to run only tests marked as slow

✅ Expected Result: Only the test function marked with @pytest.mark.slow runs successfully, and pytest does not show any warnings about unregistered markers

Automation Requirements - pytest

Assertions Needed:

Verify that tests marked with 'slow' run when using '-m slow'

Verify no warnings about unregistered markers appear during test run

Best Practices:

Register custom markers in pytest.ini under [pytest] section

Use descriptive marker names and descriptions

Avoid hardcoding markers in test code without registration

Run pytest with '-m' option to filter tests by marker

Automated Solution

PyTest

[pytest]
markers =
    slow: marks tests as slow

# test_sample.py
import pytest

def test_fast():
    assert 1 + 1 == 2

@pytest.mark.slow
def test_slow():
    assert sum([1, 2, 3]) == 6

# Command to run in terminal:
# pytest -m slow

The pytest.ini file registers the custom marker slow under the [pytest] section. This prevents pytest from showing warnings about unregistered markers.

The test file test_sample.py contains two tests: test_fast without any marker and test_slow marked with @pytest.mark.slow.

Running pytest -m slow runs only the tests marked with slow. The assertion verifies the test logic is correct.

This setup ensures marker registration and usage are correct and warnings are avoided.

Common Mistakes - 3 Pitfalls

Not registering custom markers in pytest.ini

Using marker names inconsistently between pytest.ini and test code

{'mistake': "Running pytest without the '-m' option to filter by marker", 'why_bad': 'All tests run, so marker filtering is not tested or used', 'correct_approach': "Use 'pytest -m <marker>' to run only tests with that marker"}

Bonus Challenge

Add two more custom markers 'fast' and 'database' in pytest.ini and create tests using them. Run tests filtered by each marker.

Show Hint

Practice

1. What is the main purpose of registering markers in the pytest.ini file?

easy

A. To define test data inputs for parameterized tests

B. To organize tests and avoid warnings about unknown markers

C. To automatically generate test reports

D. To speed up test execution by caching results

Solution

1. Step 1: Understand marker registration purpose

   Markers are labels for tests that help organize and select tests to run.

2. Step 2: Recognize why registration is needed

   Registering markers in pytest.ini prevents warnings about unknown markers and keeps tests organized.

3. Final Answer:

   To organize tests and avoid warnings about unknown markers -> Option B

4. Quick Check:

   Marker registration = organize tests + avoid warnings [OK]

Hint: Markers in pytest.ini prevent warnings and organize tests [OK]

Common Mistakes:

• Thinking markers speed up tests
• Confusing markers with test data
• Assuming markers generate reports

2. Which of the following is the correct way to register a marker named slow in pytest.ini?

easy

A. [markers]
slow: marks tests as slow

B. [pytest]
markers = slow

C. [pytest]
slow = marks tests as slow

D. [markers]
slow = marks tests as slow

Solution

1. Step 1: Identify correct section header

   Markers must be registered under the [markers] section in pytest.ini.

2. Step 2: Check syntax for marker registration

   The correct syntax uses an equals sign = with a description, e.g., slow = marks tests as slow.

3. Final Answer:

   [markers] slow = marks tests as slow -> Option D

4. Quick Check:

   Markers section + equals sign = correct syntax [OK]

Hint: Use [markers] section and '=' to register markers [OK]

Common Mistakes:

• Using [pytest] instead of [markers]
• Using colon ':' instead of '='
• Listing markers without description

3. Given this pytest.ini content:

[markers]
api = marks tests as api tests
slow = marks tests as slow

What happens if you run pytest -m slow?

medium

A. Only tests marked with @pytest.mark.slow will run

B. All tests will run except those marked slow

C. Tests marked with @pytest.mark.api will run

D. Pytest will show a warning about unknown marker

Solution

1. Step 1: Understand marker filtering with -m option

   The -m option runs tests matching the given marker name.

2. Step 2: Match marker name with registered markers

   Since slow is registered and used, pytest -m slow runs only tests marked with @pytest.mark.slow.

3. Final Answer:

   Only tests marked with @pytest.mark.slow will run -> Option A

4. Quick Check:

   pytest -m marker = runs tests with that marker [OK]

Hint: pytest -m runs tests with the named marker only [OK]

Common Mistakes:

• Thinking -m excludes tests with the marker
• Confusing marker names
• Expecting warnings when marker is registered

4. You added this to your pytest.ini:

[markers]
fast marks tests as fast

But when running tests, pytest shows a warning about unknown marker 'fast'. What is the problem?

medium

A. Marker name 'fast' is reserved and cannot be used

B. Markers section header is misspelled

C. Missing '=' sign between marker name and description

D. pytest.ini file is in the wrong directory

Solution

1. Step 1: Check marker registration syntax

   The marker line must have an equals sign = between the marker name and its description.

2. Step 2: Identify missing '=' causing warning

   Here, fast marks tests as fast lacks '=', so pytest treats 'fast' as unknown marker.

3. Final Answer:

   Missing '=' sign between marker name and description -> Option C

4. Quick Check:

   Marker line needs '=' sign [OK]

Hint: Always use '=' between marker and description [OK]

Common Mistakes:

• Forgetting '=' sign
• Misspelling [markers] header
• Placing pytest.ini in wrong folder

5. You want to register two markers in pytest.ini: db for database tests and ui for user interface tests. Which pytest.ini content correctly registers both markers?

hard

A. [markers]
db = marks tests as database tests
ui = marks tests as user interface tests

B. [pytest]
markers = db, ui

C. [markers]
db: marks database tests
ui: marks UI tests

D. [pytest]
db = database tests
ui = UI tests

Solution

1. Step 1: Confirm correct section header

   Markers must be under the [markers] section, not [pytest].

2. Step 2: Verify correct syntax for each marker

   Each marker line uses = with a description, e.g., db = marks tests as database tests.

3. Step 3: Check all markers are listed separately

   Both db and ui markers are listed on separate lines with descriptions.

4. Final Answer:

   [markers] db = marks tests as database tests ui = marks tests as user interface tests -> Option A

5. Quick Check:

   Separate lines under [markers] with '=' for each marker [OK]

Hint: List each marker under [markers] with '=' and description [OK]

Common Mistakes:

• Using [pytest] instead of [markers]
• Using commas to list markers
• Using ':' instead of '='