Command-line options in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of pytest with verbose option

What is the output behavior when running pytest -v on a test file with 3 passing tests?

PyTest

def test_one():
    assert 1 == 1

def test_two():
    assert 2 == 2

def test_three():
    assert 3 == 3

A pytest shows only a summary line with dots for each test

B pytest runs tests silently without showing any test names

C pytest stops after the first test and shows only one test result

D pytest shows detailed test names and statuses for all 3 tests

💡 Hint

The -v option stands for verbose output.

The -v option makes pytest show each test's name and result instead of just dots.

❓ assertion

intermediate

Correct assertion for exit code with pytest --maxfail=1

You run pytest --maxfail=1 on a test suite with multiple failing tests. Which assertion correctly checks that pytest stopped after the first failure?

PyTest

import subprocess
result = subprocess.run(['pytest', '--maxfail=1'], capture_output=True, text=True)
exit_code = result.returncode

A assert exit_code == 1 # pytest exits with 1 on failure

B assert exit_code == None # pytest does not return exit code

C assert exit_code > 1 # pytest exits with code >1 on maxfail

D assert exit_code == 0 # pytest exits with 0 even if tests fail

💡 Hint

pytest returns 0 if all tests pass, 1 if any test fails.

pytest returns exit code 1 when tests fail, including when stopped by --maxfail.

❓ locator

advanced

Best locator for pytest to run tests in a specific directory

You want to run pytest only on tests inside the tests/integration folder. Which command correctly locates and runs those tests?

A pytest --dir=tests/integration

B pytest -k tests/integration

C pytest tests/integration

D pytest -m tests/integration

💡 Hint

pytest accepts folder paths as positional arguments to run tests there.

Passing the folder path as an argument runs tests only in that folder.

🔧 Debug

advanced

Identify the error in pytest command usage

Which pytest command will cause an error when trying to run tests with keyword expression login and not slow?

A pytest -k login and not slow

B pytest -k 'login and not slow'

C pytest -k "login and not slow"

D pytest -k "login and not slow" --maxfail=2

💡 Hint

Shell interprets unquoted words separately.

Option A lacks quotes, so shell treats 'and' and 'not' as separate commands causing error.

❓ framework

expert

Effect of pytest --tb=short option on test failure output

What is the effect of running pytest with the --tb=short option on the traceback shown for failed tests?

A Shows the full detailed traceback with all calls

B Shows a shortened traceback with only the last call and error message

C Suppresses all traceback output completely

D Shows traceback only for tests marked as slow

💡 Hint

The --tb option controls traceback verbosity.

The --tb=short option shortens the traceback to the last call and error message only.

Practice

1. What does the pytest command-line option -v do when running tests?

easy

A. Runs tests only once without reruns

B. Runs tests in quiet mode, suppressing output

C. Generates a test coverage report

D. Runs tests in verbose mode, showing each test name

Solution

1. Step 1: Understand the -v option in pytest

   The -v option stands for verbose mode, which means pytest will show detailed information about each test it runs.

2. Step 2: Compare with other options

   Options like quiet mode or coverage report are different flags, so -v specifically increases output detail.

3. Final Answer:

   Runs tests in verbose mode, showing each test name -> Option D

4. Quick Check:

   Verbose = detailed output [OK]

Hint: Verbose means more details shown during test run [OK]

Common Mistakes:

• Confusing verbose with quiet mode
• Thinking it runs tests only once
• Mixing it with coverage report option

2. Which of the following is the correct syntax to run pytest and stop after the first failure?

easy

A. pytest -x

B. pytest --stop-on-failure

C. pytest --failfast=false

D. pytest -f

Solution

1. Step 1: Recall pytest option to stop on first failure

   The correct option is -x, which tells pytest to stop after the first test failure.

2. Step 2: Check other options for correctness

   --stop-on-failure and --failfast=false are invalid, and -f is not a recognized pytest option.

3. Final Answer:

   pytest -x -> Option A

4. Quick Check:

   Stop on first failure = -x [OK]

Hint: Use -x to stop pytest after first failure [OK]

Common Mistakes:

• Using long option names that don't exist
• Confusing -f with -x
• Assuming --failfast=false stops tests

3. Given the command pytest -k 'test_add or test_subtract' -v, what will pytest do?

medium

A. Run all tests except those named test_add or test_subtract

B. Run only tests named test_add or test_subtract with verbose output

C. Run tests with names containing 'test' only

D. Run tests and stop after first failure

Solution

1. Step 1: Understand the -k option

   The -k option filters tests by substring expressions. Here, it selects tests named test_add or test_subtract.

2. Step 2: Understand the -v option

   The -v option runs tests in verbose mode, showing detailed test names and results.

3. Final Answer:

   Run only tests named test_add or test_subtract with verbose output -> Option B

4. Quick Check:

   -k filters tests, -v shows details [OK]

Hint: -k filters tests by name, -v shows details [OK]

Common Mistakes:

• Thinking -k excludes tests instead of including
• Ignoring the verbose flag
• Assuming it stops on failure

4. You run pytest --maxfail=2 -v but pytest does not stop after 2 failures. What is the likely cause?

medium

A. You need to add -x to stop after max failures

B. The option --maxfail requires a space before the number

C. The --maxfail option is deprecated and ignored

D. You must use --maxfail=2 without -v

Solution

1. Step 1: Understand --maxfail behavior

   The --maxfail option sets how many failures to allow before stopping, but it requires -x to actually stop the test run.

2. Step 2: Check command usage

   Without -x, pytest will report max failures but continue running all tests.

3. Final Answer:

   You need to add -x to stop after max failures -> Option A

4. Quick Check:

   --maxfail needs -x to stop tests [OK]

Hint: Add -x with --maxfail to stop tests early [OK]

Common Mistakes:

• Thinking --maxfail alone stops tests
• Adding space between --maxfail and number
• Assuming -v disables maxfail

5. You want to run pytest only on tests marked as slow and generate a JUnit XML report saved as results.xml. Which command is correct?

hard

A. pytest --only-mark slow --junitxml results.xml

B. pytest --mark slow --xml=results.xml

C. pytest -m slow --junitxml=results.xml

D. pytest -m slow -x --junit=results.xml

Solution

1. Step 1: Use -m to select tests by marker

   The -m option filters tests by marker name, so -m slow runs only tests marked as slow.

2. Step 2: Use --junitxml=filename to generate report

   The --junitxml=results.xml option saves test results in JUnit XML format to the specified file.

3. Step 3: Verify other options are invalid

   Options like --mark, --xml, and --only-mark are not valid pytest flags.

4. Final Answer:

   pytest -m slow --junitxml=results.xml -> Option C

5. Quick Check:

   -m for marker, --junitxml for report [OK]

Hint: Use -m for markers and --junitxml for reports [OK]

Common Mistakes:

• Using incorrect flags like --mark or --xml
• Forgetting = between --junitxml and filename
• Adding -x which stops tests unnecessarily