Docker-based test execution in PyTest - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to run pytest inside a Docker container using the correct command.

PyTest

docker run --rm -v $(pwd):/app -w /app python:3.12 [1]

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

Abash

Bpython

Cpip install pytest

Dpytest

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'python' instead of 'pytest' to run tests.

Trying to install pytest instead of running it.

The pytest command runs the tests inside the Docker container. Using python or bash won't run tests directly, and pip install pytest is for installing, not running tests.

2fill in blank

medium

Complete the code to mount the current directory into the Docker container for test access.

PyTest

docker run --rm -v [1]:/app -w /app python:3.12 pytest

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

A/usr/src/app

B$(pwd)

C/home/user

D/tmp

Attempts:

3 left

💡 Hint

Common Mistakes

Using a fixed path instead of the current directory.

Not mounting the directory, so tests can't find the code.

Using $(pwd) mounts the current directory from the host into the container, allowing tests to access the code.

3fill in blank

hard

Fix the error in the Docker command to ensure the working directory is set correctly for pytest.

PyTest

docker run --rm -v $(pwd):/app -w [1] python:3.12 pytest

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

A/app

B/home/app

C/usr/src/app

D/root

Attempts:

3 left

💡 Hint

Common Mistakes

Setting working directory to a path not matching the mounted volume.

Using default working directory which may not contain the tests.

The working directory inside the container must match the mount point /app so pytest finds the tests.

4fill in blank

hard

Fill both blanks to create a Docker command that installs pytest and runs tests inside the container.

PyTest

docker run --rm -v $(pwd):/app -w /app python:3.12 bash -c "[1] && [2]"

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

Apip install pytest

Bpytest

Cpython test.py

Dapt-get update

Attempts:

3 left

💡 Hint

Common Mistakes

Running tests without installing pytest first.

Using wrong test command like 'python test.py' instead of 'pytest'.

First, pip install pytest installs pytest, then pytest runs the tests.

5fill in blank

hard

Fill all three blanks to define a Docker Compose service that runs pytest with mounted volume and working directory.

PyTest

services:
  test:
    image: python:3.12
    volumes:
      - [1]:/app
    working_dir: [2]
    command: [3]

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

A.

B/app

Cpytest

D/usr/src/app

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong mount path or working directory.

Forgetting to set the command to 'pytest'.

The volume mounts the current directory . to /app. The working directory is set to /app, and the command runs pytest.

Practice

1. What is the main benefit of running pytest tests inside a Docker container?

easy

A. It ensures tests run in a clean, consistent environment every time.

B. It makes tests run faster than on the host machine.

C. It automatically fixes failing tests.

D. It allows tests to run without writing any test code.

Solution

1. Step 1: Understand Docker container purpose

   Docker containers provide isolated environments that are the same every time they run.

2. Step 2: Connect to pytest benefits

   Running pytest inside Docker avoids environment differences causing test failures.

3. Final Answer:

   It ensures tests run in a clean, consistent environment every time. -> Option A

4. Quick Check:

   Docker isolation = consistent test environment [OK]

Hint: Docker isolates environment to avoid setup issues [OK]

Common Mistakes:

• Thinking Docker speeds up tests automatically
• Believing Docker fixes test code errors
• Assuming tests run without writing code

2. Which of the following is the correct way to run pytest inside a Docker container with your current directory shared?

easy

A. docker run -p 8080:80 python:3.12 pytest

B. docker run -v $(pwd):/app -w /app python:3.12 pytest

C. docker build -t pytest-image . && docker run pytest-image

D. docker run --rm python:3.12 pytest /app

Solution

1. Step 1: Identify volume sharing syntax

   The -v $(pwd):/app option shares the current directory to /app inside the container.

2. Step 2: Check working directory and command

   -w /app sets the working directory, and pytest runs tests there.

3. Final Answer:

   docker run -v $(pwd):/app -w /app python:3.12 pytest -> Option B

4. Quick Check:

   Volume + workdir + pytest = correct run command [OK]

Hint: Use -v for volume and -w for working directory [OK]

Common Mistakes:

• Using -p instead of -v for volume
• Not setting working directory with -w
• Running pytest without mounting code

3. Given this Docker command:

docker run --rm -v $(pwd):/tests -w /tests python:3.12 pytest test_sample.py

What will happen if test_sample.py contains one passing and one failing test?

medium

A. Pytest will run only the passing test and ignore failures.

B. Pytest will skip the failing test and exit with zero code.

C. Docker will fail to start because of volume issues.

D. Pytest will run both tests and exit with a non-zero code indicating failure.

Solution

1. Step 1: Understand pytest behavior on failures

   Pytest runs all tests and returns a non-zero exit code if any test fails.

2. Step 2: Confirm Docker command mounts tests correctly

   The volume mounts current directory to /tests, so test_sample.py is accessible and runs.

3. Final Answer:

   Pytest will run both tests and exit with a non-zero code indicating failure. -> Option D

4. Quick Check:

   Failing test causes pytest exit code != 0 [OK]

Hint: Pytest exit code shows if tests passed or failed [OK]

Common Mistakes:

• Assuming pytest skips failing tests
• Thinking Docker volume mount fails here
• Believing pytest ignores failures

4. You run this command:

docker run -v $(pwd):/app python:3.12 pytest

But pytest does not find any tests. What is the most likely cause?

medium

A. You did not set the working directory inside the container.

B. The Python image does not have pytest installed.

C. Docker volume syntax is incorrect.

D. Tests must be named test_docker.py to run.

Solution

1. Step 1: Check working directory usage

   Without -w /app, pytest runs in root, not where tests are mounted.

2. Step 2: Understand pytest test discovery

   Pytest looks for tests in current directory; wrong directory means no tests found.

3. Final Answer:

   You did not set the working directory inside the container. -> Option A

4. Quick Check:

   Working directory missing = no tests found [OK]

Hint: Always set -w to your mounted test folder [OK]

Common Mistakes:

• Assuming pytest is missing in python image by default
• Blaming volume syntax without error
• Thinking test file names must be exact

5. You want to run pytest inside Docker and save the test report to your host machine. Which command correctly achieves this?

hard

A. docker run -v $(pwd):/app -w /app python:3.12 pytest --junitxml=/tmp/report.xml

B. docker run python:3.12 pytest --junitxml=/app/report.xml

C. docker run -v $(pwd):/app -w /app python:3.12 pytest --junitxml=/app/report.xml

D. docker run -v $(pwd):/app python:3.12 pytest --junitxml=report.xml

Solution

1. Step 1: Ensure volume mount and working directory

   Mount current directory to /app and set working directory to /app so files are accessible.

2. Step 2: Specify report path inside container

   Use --junitxml=/app/report.xml to save report inside mounted folder, making it visible on host.

3. Final Answer:

   docker run -v $(pwd):/app -w /app python:3.12 pytest --junitxml=/app/report.xml -> Option C

4. Quick Check:

   Volume + workdir + report path inside mount = correct [OK]

Hint: Set -w and use full path for report inside mounted folder [OK]

Common Mistakes:

• Not setting working directory with -w
• Using relative path without mount inside container
• Omitting volume mount so report is lost