Why markers categorize and control tests in PyTest - Quick Recap

Recall & Review

beginner

What is the main purpose of markers in pytest?

Markers help group and control tests so you can run specific sets easily, like running only slow tests or tests for a feature.

beginner

How do markers improve test execution?

Markers let you select or skip tests based on labels, saving time by running only relevant tests.

beginner

Give an example of a common pytest marker and its use.

The marker @pytest.mark.slow labels tests that take longer. You can run only fast tests by skipping slow ones.

intermediate

Why is categorizing tests with markers helpful in large projects?

It helps organize tests by feature, speed, or type, making it easier to manage and run tests efficiently.

beginner

What command runs tests with a specific marker in pytest?

Use pytest -m <marker_name> to run only tests with that marker, for example pytest -m slow runs tests marked as slow.

What does the pytest marker @pytest.mark.skip do?

A Skips the test during execution

B Runs the test twice

C Marks the test as failed

D Groups the test with others

The @pytest.mark.skip marker tells pytest to skip the test when running.

How can you run only tests marked as 'fast' in pytest?

A pytest -m fast

B pytest --fast

C pytest --only fast

D pytest -r fast

The command pytest -m fast runs only tests marked with @pytest.mark.fast.

Why use markers to categorize tests?

A To change test code behavior

B To make tests run faster automatically

C To organize tests and control which run

D To delete tests after running

Markers help organize tests and decide which ones to run or skip.

Which pytest marker would you use to skip a test conditionally?

A @pytest.mark.run

B @pytest.mark.slow

C @pytest.mark.only

D @pytest.mark.skipif

@pytest.mark.skipif skips a test if a condition is true.

What happens if you run pytest without any markers?

A Only tests with markers run

B All tests run regardless of markers

C No tests run

D Tests marked as skip run only

By default, pytest runs all tests regardless of markers unless filtered.

Explain why markers are useful for controlling test execution in pytest.

Think about how you might want to run only some tests in a big project.

Describe how you would use markers to run only slow tests in pytest.

Consider labeling tests and using a command to filter them.

Practice

1. What is the main purpose of using markers in pytest?

easy

A. To write tests faster by auto-generating code

B. To change the Python version used for tests

C. To automatically fix failing tests

D. To group tests so you can run specific sets easily

Solution

1. Step 1: Understand what markers do in pytest

   Markers are labels you add to tests to group or categorize them.

2. Step 2: Identify the main use of markers

   Markers help you run only certain groups of tests, saving time and focusing effort.

3. Final Answer:

   To group tests so you can run specific sets easily -> Option D

4. Quick Check:

   Markers group tests = B [OK]

Hint: Markers help run selected tests quickly [OK]

Common Mistakes:

• Thinking markers auto-fix tests
• Confusing markers with code generation
• Believing markers change Python version

2. Which of the following is the correct way to mark a test as 'slow' in pytest?

easy

A. @pytest.slow
def test_example(): pass

B. @pytest.mark.slow
def test_example(): pass

C. @slow_mark
def test_example(): pass

D. @mark.slow
def test_example(): pass

Solution

1. Step 1: Recall pytest marker syntax

   Markers are used with @pytest.mark.<marker_name> before the test function.

2. Step 2: Match the correct syntax

   Only '@pytest.mark.slow' is the correct way to mark a test as slow.

3. Final Answer:

   @pytest.mark.slow\ndef test_example(): pass -> Option B

4. Quick Check:

   Use @pytest.mark.marker_name = D [OK]

Hint: Use @pytest.mark.marker_name to mark tests [OK]

Common Mistakes:

• Omitting 'pytest' before 'mark'
• Using wrong decorator names
• Confusing marker syntax with other decorators

3. Given the code below, what tests will run when executing pytest -m "slow and not network"?

@pytest.mark.slow
def test_a(): pass

@pytest.mark.network
def test_b(): pass

@pytest.mark.slow
@pytest.mark.network
def test_c(): pass

def test_d(): pass

medium

A. test_b and test_c

B. test_a and test_c

C. Only test_a

D. test_a, test_b, test_c, and test_d

Solution

1. Step 1: Understand the marker expression

   The command runs tests marked 'slow' but NOT marked 'network'.

2. Step 2: Check each test's markers

   test_a is 'slow' only (runs), test_b is 'network' only (excluded), test_c is both 'slow' and 'network' (excluded), test_d has no markers (excluded).

3. Final Answer:

   Only test_a -> Option C

4. Quick Check:

   Run tests with slow and not network = C [OK]

Hint: Use 'and not' to exclude markers in pytest -m [OK]

Common Mistakes:

• Including tests with 'network' marker
• Running unmarked tests by default
• Misunderstanding boolean logic in marker expressions

4. What is wrong with this pytest marker usage?

@pytest.mark.skipif(sys.platform == 'win32')
def test_func():
    assert True

medium

A. Missing import of sys module

B. Incorrect marker name 'skipif'

C. Missing parentheses after skipif

D. Cannot use conditions in markers

Solution

1. Step 1: Check the code for required imports

   The code uses 'sys.platform' but does not import 'sys'.

2. Step 2: Verify marker syntax

   '@pytest.mark.skipif(condition)' is correct syntax, so no error there.

3. Final Answer:

   Missing import of sys module -> Option A

4. Quick Check:

   Use imports for conditions in markers [OK]

Hint: Always import modules used in marker conditions [OK]

Common Mistakes:

• Forgetting to import modules like sys
• Misnaming skipif marker
• Using skipif without condition parentheses

5. You want to run only tests marked as 'database' but skip those also marked 'slow'. Which pytest command achieves this?

hard

A. pytest -m "database and not slow"

B. pytest -m "slow and not database"

C. pytest -m "database or slow"

D. pytest -m "not database and slow"

Solution

1. Step 1: Understand the requirement

   Run tests with 'database' marker but exclude those with 'slow'.

2. Step 2: Translate to pytest marker expression

   Use 'database and not slow' to select tests marked database but not slow.

3. Final Answer:

   pytest -m "database and not slow" -> Option A

4. Quick Check:

   Use 'and not' to exclude markers [OK]

Hint: Combine markers with 'and not' to exclude tests [OK]

Common Mistakes:

• Swapping marker names in the expression
• Using 'or' instead of 'and not'
• Misunderstanding marker logic in pytest -m