Test file and function naming conventions in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Identify valid pytest test file names

Which of the following file names will pytest automatically recognize as test files when running tests?

A test_math.py, utils.py, helpers_test.py

B math_test.py, utils.py, test_helpers.py

C math.py, utils.py, helpers.py

D test_math.py, test_utils.py, math_test.py

💡 Hint

pytest looks for files starting with 'test_' or ending with '_test.py'.

pytest automatically discovers test files that start with test_ or end with _test.py. Option D lists files that follow these conventions.

🧠 Conceptual

intermediate

Identify valid pytest test function names

Which function names will pytest recognize as test functions inside a test file?

A test_addition, check_subtraction, test_multiplication

B add_test, subtract_test, multiply_test

C test_addition, test_subtraction, test_multiplication

D addition_test, test_subtraction, multiplication_test

💡 Hint

pytest looks for functions starting with 'test'.

pytest recognizes functions that start with test as test functions. Option C has all functions starting with test.

❓ assertion

advanced

Assertion failure due to incorrect test function name

Given the following test file named test_math.py with these functions, which function will NOT run during pytest execution?

PyTest

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

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

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

A check_subtract

B All functions run

C test_multiply

D test_add

💡 Hint

pytest only runs functions starting with 'test'.

pytest runs only functions whose names start with test. The function check_subtract does not start with test, so it will not run.

🔧 Debug

advanced

Debug why pytest does not find tests in a file

You have a file named mathTests.py with functions named test_add and test_subtract. When running pytest, no tests are found. What is the most likely reason?

A Function names do not start with 'test'

B File name does not start with 'test_' or end with '_test.py'

C Functions are missing assert statements

D pytest is not installed

💡 Hint

pytest discovers test files by their names.

pytest discovers test files only if their names start with test_ or end with _test.py. The file mathTests.py does not follow this convention, so pytest ignores it.

❓ framework

expert

Best practice for organizing pytest test files and functions

Which of the following is the best practice for naming pytest test files and functions to ensure automatic discovery and clear organization?

A Name test files starting with 'test_' and test functions starting with 'test_', use descriptive names for both

B Name test files with any name, but test functions must start with 'test_'

C Name test files ending with '_test.py' but test functions can have any name

D Name test files and functions with any names as long as they are in a 'tests' folder

💡 Hint

pytest discovers tests based on file and function name patterns.

Best practice is to name test files starting with test_ or ending with _test.py and test functions starting with test_. Using descriptive names helps clarity and maintenance.

Practice

1. Which of the following is a correct name for a pytest test file?

easy

A. test_example.py

B. example_tested.py

C. example.py

D. mytestfile.py

Solution

1. Step 1: Understand pytest file naming rules

   Pytest requires test files to start with test_ or end with _test.py.

2. Step 2: Check each option against the rule

   test_example.py starts with test_, so it is correct. Options A, C, and D do not follow the naming convention.

3. Final Answer:

   test_example.py -> Option A

4. Quick Check:

   File starts with 'test_' = B [OK]

Hint: Test files start with 'test_' or end with '_test.py' [OK]

Common Mistakes:

• Naming file without 'test_' prefix or '_test.py' suffix
• Using generic file names without test indication
• Confusing test function naming with file naming

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

easy

A. login_test()

B. check_login()

C. test_login()

D. TestLogin()

Solution

1. Step 1: Recall pytest function naming rule

   Pytest requires test functions to start with test_ to be discovered automatically.

2. Step 2: Evaluate each function name

   Only test_login() starts with test_. Others do not follow the rule.

3. Final Answer:

   test_login() -> Option C

4. Quick Check:

   Function starts with 'test_' = A [OK]

Hint: Test functions must start with 'test_' [OK]

Common Mistakes:

• Omitting 'test_' prefix in function names
• Using camel case instead of snake case
• Confusing test file and function naming rules

3. Given the following test file named test_math.py with this code:

def add(a, b):
    return a + b

def test_add():
    assert add(2, 3) == 5

What will pytest do when run on this file?

medium

A. Run the test function and fail

B. Run the test function and pass

C. Skip the test function

D. Raise a syntax error

Solution

1. Step 1: Check file and function naming

   The file is named test_math.py and the function is named test_add, both following pytest conventions.

2. Step 2: Analyze test function behavior

   The test asserts add(2, 3) == 5, which is true, so the test will pass.

3. Final Answer:

   Run the test function and pass -> Option B

4. Quick Check:

   Correct naming + passing assertion = A [OK]

Hint: Correct names run tests; passing asserts pass tests [OK]

Common Mistakes:

• Misnaming test functions so pytest skips them
• Assuming test fails without checking assertion
• Confusing syntax errors with test failures

4. You have a test file named math_test.py with a function named add_test(). When running pytest, no tests are found. What is the most likely cause?

medium

A. The function name does not start with 'test_'

B. The file extension is incorrect

C. The file name does not start with 'test_'

D. The test function has no assert statement

Solution

1. Step 1: Check file naming

   The file math_test.py ends with _test.py, which is valid for pytest discovery.

2. Step 2: Check function naming

   The function is named add_test(), which does not start with test_. Pytest ignores such functions.

3. Final Answer:

   The function name does not start with 'test_' -> Option A

4. Quick Check:

   Function must start with 'test_' = C [OK]

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

Common Mistakes:

• Assuming file name alone is enough
• Naming functions with '_test' suffix instead of prefix
• Forgetting to add assert statements

5. You want pytest to automatically discover and run tests in your project. Which combination of file and function names will ensure this?

• File: example_test.py
• Functions: test_case1(), case2_test(), test_case3()

Which functions will pytest run?

hard

A. None of the functions

B. Only case2_test()

C. All three functions

D. Only test_case1() and test_case3()

Solution

1. Step 1: Confirm file naming

   The file example_test.py ends with _test.py, so pytest will discover it.

2. Step 2: Check function naming rules

   Pytest runs functions starting with test_. So test_case1() and test_case3() will run. case2_test() will be ignored.

3. Final Answer:

   Only test_case1() and test_case3() -> Option D

4. Quick Check:

   Functions start with 'test_' run = D [OK]

Hint: File ends '_test.py'; functions start 'test_' to run [OK]

Common Mistakes:

• Thinking '_test' suffix in function name triggers test
• Assuming all functions in test files run automatically
• Confusing file and function naming rules