pytest-xdist installation - Build an Automation Script

Verify pytest-xdist installation and parallel test execution

Preconditions (3)

Step 1: Open a terminal or command prompt

Step 2: Run the command 'pip install pytest-xdist' to install pytest-xdist

Step 3: Verify the installation by running 'pytest --version' and check that pytest-xdist is listed

Step 4: Run tests in parallel using the command 'pytest -n 2' to execute tests with 2 workers

Step 5: Observe the test execution output

✅ Expected Result: pytest-xdist is installed successfully, pytest --version shows pytest-xdist, and tests run in parallel with 2 workers without errors

Automation Requirements - pytest

Assertions Needed:

Verify pytest-xdist is installed by checking output of 'pytest --version' contains 'xdist'

Verify tests run with '-n 2' option complete successfully

Verify the number of workers used is 2 as shown in test output

Best Practices:

Use subprocess module to run shell commands and capture output

Use assertions to check command outputs

Isolate test environment to avoid dependency conflicts

Provide clear error messages on failure

Automated Solution

PyTest

import subprocess
import sys
import pytest

def test_pytest_xdist_installation_and_parallel_run():
    # Step 1: Install pytest-xdist
    install_cmd = [sys.executable, '-m', 'pip', 'install', 'pytest-xdist']
    install_result = subprocess.run(install_cmd, capture_output=True, text=True)
    assert install_result.returncode == 0, f"Failed to install pytest-xdist: {install_result.stderr}"

    # Step 2: Verify pytest-xdist is listed in pytest --version
    version_cmd = ['pytest', '--version']
    version_result = subprocess.run(version_cmd, capture_output=True, text=True)
    assert version_result.returncode == 0, f"pytest --version failed: {version_result.stderr}"
    assert 'xdist' in version_result.stdout, "pytest-xdist not found in pytest --version output"

    # Step 3: Run tests in parallel with 2 workers
    run_cmd = ['pytest', '-n', '2', '--maxfail=1', '--disable-warnings', 'test_sample.py']
    run_result = subprocess.run(run_cmd, capture_output=True, text=True)
    assert run_result.returncode == 0, f"Parallel test run failed: {run_result.stderr}"

    # Step 4: Check output contains info about 2 workers
    assert 'gw0' in run_result.stdout and 'gw1' in run_result.stdout, "Parallel workers output missing"

This test script automates the manual test case steps.

First, it installs pytest-xdist using pip via subprocess and asserts the installation succeeded.

Next, it runs pytest --version and checks that 'xdist' appears in the output, confirming pytest-xdist is installed.

Then, it runs pytest with the -n 2 option to execute tests in parallel with 2 workers, asserting the tests pass.

Finally, it verifies the output contains worker identifiers gw0 and gw1, which pytest-xdist uses to label parallel workers.

Using subprocess allows running shell commands from Python and capturing their output for assertions.

This approach ensures the installation and parallel execution features of pytest-xdist work as expected.

Common Mistakes - 3 Pitfalls

{'mistake': 'Not capturing subprocess output and blindly assuming commands succeed', 'why_bad': "If the install or test run fails, the script won't detect it and will give false positives", 'correct_approach': 'Always capture output and check return codes to verify success'}

{'mistake': "Hardcoding 'pytest' command without considering environment", 'why_bad': "The 'pytest' command might not be found if environment paths differ or virtual environments are used", 'correct_approach': "Use sys.executable with '-m pytest' or ensure environment is correctly set"}

{'mistake': 'Not verifying that pytest-xdist is actually installed before running parallel tests', 'why_bad': 'Tests may fail or run serially without clear indication why', 'correct_approach': "Check 'pytest --version' output includes 'xdist' before running parallel tests"}

Bonus Challenge

Now add data-driven testing to run the parallel test execution with 1, 2, and 3 workers

Show Hint