Running tests (pytest command) - Build an Automation Script

Run pytest tests and verify output

Preconditions (3)

Step 1: Open a terminal or command prompt

Step 2: Navigate to the directory containing test_sample.py

Step 3: Run the command: pytest

Step 4: Observe the test execution output in the terminal

✅ Expected Result: pytest runs all tests in test_sample.py and shows a summary with number of tests passed or failed

Automation Requirements - pytest

Assertions Needed:

Verify that pytest command runs without errors

Verify that the test output contains '1 passed' for the sample test

Best Practices:

Use assert statements inside test functions

Keep test files and functions named with 'test_' prefix

Run pytest from the command line in the correct directory

Automated Solution

PyTest

import subprocess
import sys

def test_run_pytest_command():
    # Run pytest command on test_sample.py
    result = subprocess.run([sys.executable, '-m', 'pytest', 'test_sample.py'], capture_output=True, text=True)
    # Check that pytest exited with code 0 (success)
    assert result.returncode == 0, f"pytest failed with code {result.returncode}"
    # Check output contains '1 passed' indicating one test passed
    assert '1 passed' in result.stdout, "Expected '1 passed' in pytest output"

This test runs the pytest command on the test_sample.py file using Python's subprocess module.

We capture the output and check the return code to ensure pytest ran successfully.

Then we assert that the output contains '1 passed' which means one test passed as expected.

This simulates running pytest from the command line and verifies the test execution result.

Common Mistakes - 3 Pitfalls

Not capturing output from the pytest command

Running pytest without specifying the test file or directory

Not checking the return code of the pytest command

Bonus Challenge

Now add data-driven testing by running pytest on three different test files and verify each output

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