Test file and function naming conventions in PyTest - Cheat Sheet & Quick Revision

Recall & Review

beginner

Why should test files in pytest start with test_?

Pytest automatically discovers test files that start with test_ or end with _test.py. This naming helps pytest find and run your tests without extra configuration.

beginner

What is the recommended naming pattern for test functions in pytest?

Test functions should start with test_. For example, def test_addition():. This allows pytest to recognize and run them as tests.

beginner

Can you name a test file calculator.py and expect pytest to run tests inside it automatically?

No. Pytest will not discover tests in files without the test_ prefix or _test.py suffix. The file should be named like test_calculator.py.

beginner

What happens if a test function does not start with test_ in pytest?

Pytest will ignore the function because it does not match the naming pattern for test functions. Only functions starting with test_ are run as tests.

beginner

Why is consistent naming important in test files and functions?

Consistent naming helps pytest find tests automatically, keeps your project organized, and makes it easier for others to understand and run your tests.

Which of these is a valid pytest test file name?

A test_math.py

B math_tested.py

C math.py

D testing_math.py

Pytest recognizes files starting with 'test_' or ending with '_test.py'. Only 'test_math.py' fits this pattern.

How should you name a test function for pytest to recognize it?

A test_addition()

B addition_test()

C check_addition()

D AddTest()

Test functions must start with 'test_' for pytest to discover and run them.

If a test file is named calculator.py, what will pytest do?

A Run all tests inside it

B Ignore it during test discovery

C Run tests only if specified manually

D Rename it automatically

Pytest ignores files without 'test_' prefix or '_test.py' suffix during automatic test discovery.

What prefix should test functions have in pytest?

A check_

B verify_

C assert_

D test_

The 'test_' prefix is required for pytest to recognize functions as tests.

Why is it important to follow naming conventions in pytest?

A To reduce code size

B To make tests run faster

C To allow pytest to find and run tests automatically

D To avoid writing assertions

Naming conventions help pytest discover tests without extra setup.

Explain the naming conventions for test files and test functions in pytest and why they matter.

Think about how pytest finds tests without manual configuration.

What happens if you name a test function without the 'test_' prefix in pytest?

Consider how pytest identifies test functions.

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