Pytest - Parameterizing Tests

Parameterizing of a test is done to run the test against multiple sets of inputs. We can do this by using the following marker −

@pytest.mark.parametrize

Copy the below code into a file called test_multiplication.py −

test_multiplication.py

import pytest

@pytest.mark.parametrize("num, output",[(1,11),(2,22),(3,35),(4,44)])
def test_multiplication_11(num, output):
   assert 11*num == output

Here the test multiplies an input with 11 and compares the result with the expected output. The test has 4 sets of inputs, each has 2 values one is the number to be multiplied with 11 and the other is the expected result.

Execute the test by running the following command −

pytest -k multiplication -v

The above command will generate the following output −

============================ test session starts ================================
platform win32 -- Python 3.14.2, pytest-9.0.2, pluggy-1.6.0 
-- C:\Users\mahes\AppData\Local\Programs\Python\Python314\python.exe
cachedir: .pytest_cache
rootdir: D:\Projects\python\myenv\automation
collected 12 items / 8 deselected / 4 selected

test_multiplication.py::test_multiplication_11[1-11] PASSED                 [ 25%]
test_multiplication.py::test_multiplication_11[2-22] PASSED                 [ 50%]
test_multiplication.py::test_multiplication_11[3-35] FAILED                 [ 75%]
test_multiplication.py::test_multiplication_11[4-44] PASSED                 [100%]

============================ FAILURES ============================================
____________________________ test_multiplication_11[3-35] ________________________

num = 3, output = 35

    @pytest.mark.parametrize("num, output",[(1,11),(2,22),(3,35),(4,44)])
    def test_multiplication_11(num, output):
>   assert 11*num == output
E      assert (11 * 3) == 35

test_multiplication.py:5: AssertionError
============================ short test summary info ==============================
FAILED test_multiplication.py::test_multiplication_11[3-35] - assert (11 * 3) == 35
============================ 1 failed, 3 passed, 8 deselected in 0.08s ============