Parametrize & Markers — Pytest for Python Testing | Sabaoon Academy

@pytest.mark.parametrize eliminates copy-pasted tests by generating multiple test cases from a single function. Markers let you categorise, skip, and xfail individual tests.

@pytest.mark.parametrize

import pytest

def is_palindrome(word):
    return word == word[::-1]

@pytest.mark.parametrize("word,expected", [
    ("racecar", True),
    ("hello",   False),
    ("level",   True),
    ("python",  False),
    ("noon",    True),
])
def test_palindrome(word, expected):
    assert is_palindrome(word) == expected

pytest generates 5 separate test cases — each appears independently in the output:

PASSED test_strings.py::test_palindrome[racecar-True]
PASSED test_strings.py::test_palindrome[hello-False]
PASSED test_strings.py::test_palindrome[level-True]

Multiple Parameters

@pytest.mark.parametrize("a,b,expected", [
    (1, 2, 3),
    (0, 0, 0),
    (-1, 1, 0),
    (100, 200, 300),
])
def test_add(a, b, expected):
    assert a + b == expected

Parametrize Visualiser

Parametrize test generation

Ctrl+Enter

HTML

CSS

var code = [
'@pytest.mark.parametrize("word,expected", [',
'    ("racecar", True),',
'    ("hello",   False),',
'    ("level",   True),',
'    ("python",  False),',
'    ("noon",    True),',
'])',
'def test_palindrome(word, expected):',
'    assert is_palindrome(word) == expected',
];

document.getElementById('template').textContent = code.join('\n');

var cases = [
{ id: 'racecar-True',  pass: true  },
{ id: 'hello-False',   pass: true  },
{ id: 'level-True',    pass: true  },
{ id: 'python-False',  pass: true  },
{ id: 'noon-True',     pass: true  },
];

var container = document.getElementById('cases');

document.getElementById('expandBtn').onclick = function() {
container.innerHTML = '';
cases.forEach(function(c) {
  var div = document.createElement('div');
  div.className = 'case';
  div.id = 'c-' + c.id;
  div.innerHTML =
    '<div class="dot"></div>' +
    '<span>test_palindrome[' + c.id + ']</span>' +
    '<span class="result" id="r-' + c.id + '"></span>';
  container.appendChild(div);
});

this.disabled = true;
var i = 0;
var btn = this;
function reveal() {
  if (i >= cases.length) {
    btn.disabled = false;
    console.log(cases.length + ' test cases generated from 1 function');
    return;
  }
  var c = cases[i];
  var el = document.getElementById('c-' + c.id);
  el.classList.add('visible');
  setTimeout(function() {
    document.getElementById('r-' + c.id).textContent = 'PASSED';
    console.log('PASSED test_palindrome[' + c.id + ']');
  }, 250);
  i++;
  setTimeout(reveal, 200);
}
reveal();
};

Preview

Built-in Markers

# Skip a test
@pytest.mark.skip(reason="Not implemented yet")
def test_export():
    pass

# Skip conditionally
import sys
@pytest.mark.skipif(sys.platform == "win32", reason="Linux only")
def test_file_permissions():
    pass

# Expected failure
@pytest.mark.xfail(reason="Known bug #123")
def test_edge_case():
    assert my_func(None) == ""   # currently raises TypeError

# Slow test — requires --runslow flag
@pytest.mark.slow
def test_full_export():
    pass

Custom Markers

# pytest.ini
[pytest]
markers =
    slow: marks tests as slow (deselect with -m "not slow")
    integration: marks tests that hit real external services
    smoke: marks critical path tests

Run subsets:

pytest -m smoke          # only smoke tests
pytest -m "not slow"     # skip slow tests
pytest -m "integration or smoke"