Docker-based test execution in PyTest - Test Execution Trace

Test Overview

This test runs a simple pytest test inside a Docker container. It verifies that the test code executes correctly in the isolated Docker environment and the test passes.

Test Code - pytest

PyTest

import pytest

def test_addition():
    assert 2 + 3 == 5

# Dockerfile content:
# FROM python:3.12-slim
# WORKDIR /app
# COPY test_script.py /app/
# RUN pip install pytest
# CMD ["pytest", "test_script.py"]

Execution Trace - 4 Steps

Step	Action	System State	Assertion	Result
1	Docker daemon starts and builds the image from Dockerfile	Docker image with Python 3.12 and pytest installed is created	-	PASS
2	Docker container starts from the built image	Container running with working directory /app containing test_script.py	-	PASS
3	pytest runs test_addition inside the container	pytest executes test and outputs result	assert 2 + 3 == 5 is True	PASS
4	pytest finishes and container stops	Test passed, container exits cleanly	Test report shows 1 passed, 0 failed	PASS

Failure Scenario

Failing Condition: Test assertion fails inside the Docker container

Execution Trace Quiz - 3 Questions

What ensures the test runs in an isolated environment?

A Running pytest directly on the host machine

B Running pytest inside a Docker container

C Using assert statements in the test

D Installing pytest globally on the host

Key Result

Running tests inside Docker containers ensures a consistent environment, avoiding differences between developer machines and CI servers.