Grouping related tests in PyTest - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of grouping related tests in pytest?

Grouping related tests helps organize tests logically, making them easier to read, maintain, and run selectively.

beginner

How can you group related tests in pytest using functions?

You can group related tests by placing them in the same Python file or by using classes without __init__ methods to logically group test functions.

intermediate

What is a pytest test class and how does it help in grouping tests?

A pytest test class is a class whose name starts with 'Test'. It groups related test functions inside it, helping organize tests and share setup code.

intermediate

How do pytest markers help in grouping tests?

Markers label tests with custom tags. You can run tests with specific markers to group and execute related tests selectively.

beginner

Give an example of grouping tests using a pytest class.

Example:
class TestMathOperations:
    def test_add(self):
        assert 1 + 1 == 2
    def test_subtract(self):
        assert 2 - 1 == 1
This groups add and subtract tests logically.

Which of the following is a valid way to group related tests in pytest?

A Using test classes with names starting with 'Test'

B Writing all tests in one long function

C Using global variables to separate tests

D Running tests in random order

Test classes starting with 'Test' group related test functions logically in pytest.

What is the benefit of using pytest markers for grouping tests?

A They disable tests permanently

B They speed up test execution automatically

C They convert tests into functions

D They allow running only selected groups of tests

Markers tag tests so you can run only those with a specific marker, grouping tests for selective execution.

How do you name a pytest test class to ensure pytest recognizes it?

A Start the class name with 'Test'

B End the class name with 'Test'

C Include 'test' anywhere in the class name

D Use uppercase letters only

Pytest recognizes test classes whose names start with 'Test'.

Which statement about grouping tests in pytest is TRUE?

A Grouping tests slows down test execution

B Grouping tests helps maintain and run tests more easily

C Grouping tests is not supported in pytest

D Grouping tests requires special plugins only

Grouping tests improves organization and selective running, making maintenance easier.

What is the recommended way to share setup code among grouped tests in pytest?

A Use global variables outside tests

B Copy-paste setup code in every test

C Use setup methods inside test classes or fixtures

D Run tests in a specific order

Setup methods or fixtures allow sharing setup code cleanly among grouped tests.

Explain how you can group related tests in pytest and why it is useful.

Think about classes, markers, and file organization.

Describe how pytest markers work for grouping tests and how to run tests with a specific marker.

Focus on marking and running tests selectively.

Practice

1. What is the main benefit of grouping related tests in pytest?

easy

A. It keeps the test suite organized and easier to manage

B. It makes tests run faster automatically

C. It removes the need for assertions in tests

D. It prevents tests from running in parallel

Solution

1. Step 1: Understand test grouping purpose

   Grouping tests helps organize them logically by feature or behavior.

2. Step 2: Identify the main benefit

   This organization makes the test suite easier to maintain and understand.

3. Final Answer:

   It keeps the test suite organized and easier to manage -> Option A

4. Quick Check:

   Grouping = Organized tests [OK]

Hint: Grouping means organizing tests for easier management [OK]

Common Mistakes:

• Thinking grouping speeds up tests automatically
• Believing grouping removes need for assertions
• Assuming grouping disables parallel runs

2. Which of the following is the correct way to mark a test function with a group name in pytest?

easy

A. @pytest.group('fast')\ndef test_example(): pass

B. @pytest.group_mark('fast')\ndef test_example(): pass

C. @pytest.mark.fast\ndef test_example(): pass

D. @pytest.tag('fast')\ndef test_example(): pass

Solution

1. Step 1: Recall pytest syntax for marking tests

   pytest uses @pytest.mark.<groupname> to mark tests for grouping.

2. Step 2: Match correct syntax

   @pytest.mark.fast is the correct decorator to mark a test as 'fast'.

3. Final Answer:

   @pytest.mark.fast\ndef test_example(): pass -> Option C

4. Quick Check:

   Use @pytest.mark.groupname for grouping [OK]

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

Common Mistakes:

• Using @pytest.group instead of @pytest.mark
• Using @pytest.tag which does not exist
• Incorrect decorator names like @pytest.group_mark

3. Given the following pytest code, what tests will run when executing pytest -m "slow"?

import pytest

@pytest.mark.slow
def test_a():
    assert True

@pytest.mark.fast
def test_b():
    assert True

class TestGroup:
    @pytest.mark.slow
    def test_c(self):
        assert True

    def test_d(self):
        assert True

medium

A. test_a and test_c only

B. test_b and test_d only

C. All tests test_a, test_b, test_c, test_d

D. Only test_c

Solution

1. Step 1: Understand pytest -m option

   The -m option runs tests marked with the given marker, here 'slow'.

2. Step 2: Identify tests marked 'slow'

   test_a and test_c have @pytest.mark.slow, so they run. test_b and test_d do not.

3. Final Answer:

   test_a and test_c only -> Option A

4. Quick Check:

   -m "slow" runs tests marked slow [OK]

Hint: -m runs only tests with the matching mark [OK]

Common Mistakes:

• Running all tests ignoring marks
• Including unmarked tests in filtered run
• Confusing class-level marks with method marks

4. What is wrong with this pytest code if the goal is to group tests inside a class named TestMath?

class TestMath:
    def test_add():
        assert 1 + 1 == 2

    def test_subtract(self):
        assert 2 - 1 == 1

medium

A. test_subtract should not have self parameter

B. Class name should not start with Test

C. Tests inside classes cannot have assertions

D. test_add is missing the self parameter

Solution

1. Step 1: Check method definitions inside test classes

   Instance methods inside test classes must have self as first parameter.

2. Step 2: Identify the error

   test_add is missing self, so pytest will error or skip it.

3. Final Answer:

   test_add is missing the self parameter -> Option D

4. Quick Check:

   Test methods in classes need self [OK]

Hint: Test methods in classes must include self parameter [OK]

Common Mistakes:

• Omitting self in test methods
• Thinking class names cannot start with Test
• Removing assertions from test methods

5. You want to run only tests related to the login feature in your pytest suite. You have marked tests with @pytest.mark.login and grouped some inside a class TestLogin. Which command will correctly run all login tests, including those inside the class?

hard

A. pytest -k login

B. pytest -m login

C. pytest --group=login

D. pytest --run-login

Solution

1. Step 1: Understand pytest options for running grouped tests

   pytest uses -m to run tests marked with a specific marker like 'login'.

2. Step 2: Identify correct command

   pytest -m login runs all tests marked with @pytest.mark.login, including those inside classes.

3. Final Answer:

   pytest -m login -> Option B

4. Quick Check:

   -m runs marked tests, -k filters by test name [OK]

Hint: Use -m with marker name to run grouped tests [OK]

Common Mistakes:

• Using -k which filters by test name, not marker
• Using nonexistent options like --group or --run-login
• Assuming class name filters tests automatically