Test packages in PyTest - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import pytest in a test file.

PyTest

import [1]

Drag options to blanks, or click blank then click option'

Apytest

Bunittest

Crequests

Dos

Attempts:

3 left

💡 Hint

Common Mistakes

Importing unittest instead of pytest

Importing unrelated modules

pytest is the testing framework used to write and run tests.

2fill in blank

medium

Complete the code to define a test function inside a test package.

PyTest

def [1]():
    assert 1 + 1 == 2

Drag options to blanks, or click blank then click option'

Atest_sum

Bcheck_sum

Csum_test

DsumCheck

Attempts:

3 left

💡 Hint

Common Mistakes

Not starting function name with 'test'

Using camelCase instead of snake_case

pytest recognizes functions starting with 'test' as test cases.

3fill in blank

hard

Fix the error in the test package __init__.py to make it a package.

PyTest

# This file makes the directory a package
[1]

Drag options to blanks, or click blank then click option'

A__init__.py

Bdef test(): pass

Cimport pytest

Dpass

Attempts:

3 left

💡 Hint

Common Mistakes

Leaving __init__.py empty

Adding unnecessary code causing errors

An empty __init__.py file with 'pass' makes the folder a package without errors.

4fill in blank

hard

Fill both blanks to create a test package with a test module and a test function.

PyTest

tests/
  __init__.py
  test_math.py

# Inside test_math.py:
def [1]():
    assert 3 * 3 == [2]

Drag options to blanks, or click blank then click option'

Atest_multiplication

B9

Ctest_addition

D6

Attempts:

3 left

💡 Hint

Common Mistakes

Wrong function name not starting with 'test'

Wrong expected value in assertion

The function name must start with 'test' and the assertion must check the correct product 9.

5fill in blank

hard

Fill all three blanks to create a test package with a test module, test function, and a failing assertion.

PyTest

tests/
  __init__.py
  test_strings.py

# Inside test_strings.py:
def [1]():
    result = 'hello'.upper()
    assert result == '[2]'
    assert result != '[3]'

Drag options to blanks, or click blank then click option'

Atest_uppercase

BHELLO

Chello

Dtest_lowercase

Attempts:

3 left

💡 Hint

Common Mistakes

Wrong function name

Wrong expected string in assertion

Confusing uppercase and lowercase

The test function checks that 'hello'.upper() equals 'HELLO' and is not 'hello'.

Practice

1. What is the main purpose of a test package in pytest?

easy

A. To group related test files into a folder with an __init__.py file

B. To run tests only from a single test file

C. To create a virtual environment for tests

D. To install pytest dependencies automatically

Solution

1. Step 1: Understand test package structure

   A test package groups related test files inside a folder that contains an __init__.py file.

2. Step 2: Purpose of grouping tests

   This grouping helps organize tests and allows pytest to find and run them together.

3. Final Answer:

   To group related test files into a folder with an __init__.py file -> Option A

4. Quick Check:

   Test packages group tests = A [OK]

Hint: Test packages group tests in folders with __init__.py [OK]

Common Mistakes:

• Confusing test packages with virtual environments
• Thinking test packages run only one file
• Believing pytest installs dependencies automatically

2. Which of the following is the correct way to make a folder a test package in pytest?

easy

A. Add a file named test_package.py inside the folder

B. Create a file named setup.py inside the folder

C. Add a file named __init__.py inside the folder

D. Add a file named requirements.txt inside the folder

Solution

1. Step 1: Identify the marker for Python packages

   Python treats folders with an __init__.py file as packages, including test packages.

2. Step 2: Confirm pytest package recognition

   pytest uses this file to recognize the folder as a test package and find tests inside it.

3. Final Answer:

   Add a file named __init__.py inside the folder -> Option C

4. Quick Check:

   __init__.py marks test packages = B [OK]

Hint: Add __init__.py to folder to make it a test package [OK]

Common Mistakes:

• Adding test files instead of __init__.py to mark package
• Confusing setup.py with package marker
• Using requirements.txt for package identification

3. Given this folder structure:

tests/
  __init__.py
  test_math.py
  test_string.py

What will happen when you run pytest tests/?

medium

A. pytest will skip all tests because folder has __init__.py

B. pytest will run only test_math.py tests

C. pytest will raise an error because __init__.py is present

D. pytest will run all tests in both test_math.py and test_string.py

Solution

1. Step 1: Understand pytest test discovery in packages

   pytest finds and runs all test files inside a test package folder when you run pytest on that folder.

2. Step 2: Effect of __init__.py on test discovery

   The presence of __init__.py marks the folder as a package but does not prevent pytest from running tests inside.

3. Final Answer:

   pytest will run all tests in both test_math.py and test_string.py -> Option D

4. Quick Check:

   pytest runs all tests in package folder = D [OK]

Hint: pytest runs all tests in package folder with __init__.py [OK]

Common Mistakes:

• Thinking __init__.py blocks test discovery
• Assuming only one test file runs
• Expecting errors due to __init__.py presence

4. You have a folder tests/ with test files but forgot to add __init__.py. What issue might you face?

medium

A. pytest will not recognize the folder as a test package and may skip tests inside

B. pytest will raise a syntax error when running tests

C. pytest will run tests twice

D. pytest will automatically create __init__.py for you

Solution

1. Step 1: Role of __init__.py in test packages

   Without __init__.py, the folder is not a recognized Python package, so pytest may not treat it as a test package.

2. Step 2: Effect on test discovery

   pytest might skip tests inside such folders or not group them properly during test runs.

3. Final Answer:

   pytest will not recognize the folder as a test package and may skip tests inside -> Option A

4. Quick Check:

   Missing __init__.py can cause pytest to skip tests = C [OK]

Hint: Always add __init__.py to test folders to avoid skipped tests [OK]

Common Mistakes:

• Expecting syntax errors without __init__.py
• Thinking pytest auto-creates __init__.py
• Assuming tests run twice without __init__.py

5. You want to organize tests for a large project using pytest. You create nested folders with __init__.py files like this:

tests/
  __init__.py
  unit/
    __init__.py
    test_utils.py
  integration/
    __init__.py
    test_api.py

How can you run only the integration tests using pytest?

hard

A. Run pytest tests/ and pytest will run only integration tests automatically

B. Run pytest tests/integration/ to run only integration tests

C. Run pytest tests/unit/ to run integration tests

D. Remove __init__.py files to run only integration tests

Solution

1. Step 1: Understand folder-based test selection

   pytest runs tests in the folder path you specify. To run only integration tests, specify the integration folder.

2. Step 2: Confirm effect of nested __init__.py files

   Nested __init__.py files mark subfolders as packages but do not affect running tests by folder path.

3. Final Answer:

   Run pytest tests/integration/ to run only integration tests -> Option B

4. Quick Check:

   Run pytest on specific folder to run its tests = A [OK]

Hint: Run pytest on specific test folder to run only those tests [OK]

Common Mistakes:

• Expecting pytest to auto-filter integration tests without folder path
• Running wrong folder path for desired tests
• Removing __init__.py thinking it filters tests