Test naming conventions in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of pytest test discovery with naming

Given the following test functions in a file named test_math.py, which tests will pytest discover and run?

PyTest

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

def check_subtraction():
    assert 2 - 1 == 1

def testMultiply():
    assert 2 * 3 == 6

class TestOperations:
    def test_divide(self):
        assert 6 / 2 == 3
    def divide_test(self):
        assert 6 / 3 == 2

A test_addition, testMultiply, test_divide

B test_addition, test_divide

C test_addition, check_subtraction, testMultiply, test_divide, divide_test

D test_addition, testMultiply, test_divide, divide_test

💡 Hint

pytest discovers test functions and methods that start with test_ or are in classes named Test* with methods starting with test_.

pytest discovers functions starting with test_ and methods in classes named Test* starting with test_. So test_addition, testMultiply (not starting with test_), and test_divide are considered. However, testMultiply does not start with test_ so it is not discovered. The correct discovered tests are test_addition and test_divide. But testMultiply is not discovered. So only test_addition and test_divide run. Option B incorrectly includes testMultiply. Reconsider options carefully.

❓ assertion

intermediate

Correct assertion for test function name check

Which assertion correctly verifies that a test function name func_name follows pytest naming conventions?

PyTest

func_name = "test_example"

A assert func_name.startswith("test_")

B assert func_name.endswith("_test")

C assert "test" in func_name

D assert func_name == "testExample"

💡 Hint

pytest requires test function names to start with test_.

The correct assertion checks if the function name starts with test_. Option A does this correctly. Option A checks the wrong end of the string. Option A is too broad and allows names like mytestfunc. Option A checks for an exact name which is not general.

🔧 Debug

advanced

Identify why pytest skips a test function

Why does pytest skip the following test function during discovery?

PyTest

def Test_login():
    assert True

A Function is missing a decorator to mark it as a test

B Function is inside a class without 'Test' prefix

C Function name is too short

D Function name does not start with lowercase 'test_'

💡 Hint

pytest requires test functions to start with test_ in lowercase.

pytest discovers test functions only if their names start with lowercase test_. Here, the function name starts with uppercase T, so pytest skips it.

🧠 Conceptual

advanced

Best practice for test class naming in pytest

Which is the best practice for naming test classes in pytest to ensure test discovery?

A Class names should start with 'Test' and include an __init__ method

B Class names should start with 'test' in lowercase and have an __init__ method

C Class names should start with 'Test' and not have an __init__ method

D Class names can be any name as long as methods start with 'test_'

💡 Hint

pytest discovers test classes starting with 'Test' and ignores classes with __init__ methods.

pytest discovers test classes whose names start with 'Test' (uppercase T) and which do not define an __init__ method. Having an __init__ method prevents pytest from collecting tests in that class.

❓ framework

expert

Effect of pytest.ini on test naming conventions

Given the following pytest.ini configuration, which test function name will pytest discover?

[pytest]
testpaths = tests
python_files = check_*.py
python_functions = check_*

A def check_addition(): pass

B def test_addition(): pass

C def addition_check(): pass

D def add_check(): pass

💡 Hint

pytest.ini overrides default test discovery patterns.

The configuration changes pytest to look for files starting with 'check_' and functions starting with 'check_'. So only functions named like 'check_addition' are discovered. 'test_addition' is ignored because 'python_functions' is set to 'check_*'.

Practice

1. Which of the following is the correct way to name a test function in pytest so it is automatically discovered?

easy

A. test_login_functionality

B. check_login_functionality

C. LoginTest

D. verifyLogin

Solution

1. Step 1: Understand pytest test discovery rules

   pytest automatically finds test functions that start with test_.

2. Step 2: Check each option against the rule

   Only test_login_functionality starts with test_, so pytest will find it automatically.

3. Final Answer:

   test_login_functionality -> Option A

4. Quick Check:

   Test names start with test_ = C [OK]

Hint: Test names must start with test_ to be found [OK]

Common Mistakes:

• Not starting test names with test_
• Using camelCase instead of snake_case
• Using class names instead of functions

2. Which of the following test function names is syntactically correct in pytest?

easy

A. test-user-login

B. test-UserLogin

C. test_user_login

D. test user login

Solution

1. Step 1: Identify valid Python function names

   Function names must use letters, numbers, and underscores only; no spaces or hyphens.

2. Step 2: Check each option

   test_user_login uses underscores and is valid; others use hyphens, spaces which are invalid.

3. Final Answer:

   test_user_login -> Option C

4. Quick Check:

   Underscores allowed in function names = D [OK]

Hint: Use underscores, no spaces or hyphens in test names [OK]

Common Mistakes:

• Using hyphens in function names
• Including spaces in test names
• Using camelCase instead of snake_case

3. Given the following pytest code, which test functions will pytest discover and run?

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

def check_subtraction():
    assert 2 - 1 == 1

def testMultiplication():
    assert 2 * 3 == 6

class TestDivision:
    def test_divide(self):
        assert 6 / 2 == 3

medium

A. test_addition and test_divide only

B. All four functions

C. test_addition, testMultiplication, and test_divide

D. test_addition only

Solution

1. Step 1: Identify pytest discovery rules for functions and methods

   pytest finds functions starting with test_ and methods inside classes named Test* starting with test_.

2. Step 2: Analyze each function/method

   test_addition is found; check_subtraction is ignored; testMultiplication is ignored due to camelCase; test_divide inside TestDivision class is found.

3. Final Answer:

   test_addition and test_divide only -> Option A

4. Quick Check:

   Functions/methods start with test_ = A [OK]

Hint: pytest finds test_ functions and test_ methods in Test* classes [OK]

Common Mistakes:

• Assuming camelCase test names are found
• Ignoring test methods inside Test classes
• Thinking all functions are discovered

4. You wrote a test function named Test_login but pytest does not run it. What is the most likely reason?

medium

A. Function is inside a class without Test prefix

B. Function name contains uppercase letters

C. Function is missing parentheses

D. Function name does not start with lowercase test_

Solution

1. Step 1: Recall pytest naming rules for functions

   pytest requires test functions to start with lowercase test_ exactly.

2. Step 2: Analyze the function name Test_login

   It starts with uppercase T, so pytest ignores it.

3. Final Answer:

   Function name does not start with lowercase test_ -> Option D

4. Quick Check:

   Lowercase test_ prefix required = A [OK]

Hint: Test function names must start with lowercase test_ [OK]

Common Mistakes:

• Using uppercase T in test function names
• Assuming pytest finds any function with 'test' inside
• Ignoring function naming case sensitivity

5. You want to write clear pytest test names that describe what they check. Which of the following is the best test function name for checking if a user can log in with valid credentials?

hard

A. test1

B. test_valid_user_login

C. test_login

D. test_user_login_with_valid_credentials_and_session_creation

Solution

1. Step 1: Consider clarity and brevity in test names

   Good test names are clear but not overly long or vague.

2. Step 2: Evaluate each option

   test_valid_user_login clearly states the test purpose concisely. test1 is vague. test_login is too general. test_user_login_with_valid_credentials_and_session_creation is too long and hard to read.

3. Final Answer:

   test_valid_user_login -> Option B

4. Quick Check:

   Clear and concise descriptive names = B [OK]

Hint: Choose clear, concise test names describing the check [OK]

Common Mistakes:

• Using vague or generic names like test1
• Writing overly long test names
• Using names that don't describe the test purpose