@pytest.mark.parametrize decorator - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple parametrize test

What will be the output when running this pytest test with @pytest.mark.parametrize?

PyTest

import pytest

@pytest.mark.parametrize('x,y', [(1,2), (3,4)])
def test_sum(x, y):
    assert x + y == 3

A One test passes, one test fails

B Both tests pass

C Both tests fail

D SyntaxError due to parametrize usage

💡 Hint

Check the sum of each pair and compare with 3

The first pair (1,2) sums to 3, so the assertion passes. The second pair (3,4) sums to 7, so the assertion fails.

❓ assertion

intermediate

Correct assertion for parametrize test

Which assertion correctly tests that the product of x and y equals 6 in this parametrize test?

PyTest

import pytest

@pytest.mark.parametrize('x,y', [(1,6), (2,3), (3,2)])
def test_product(x, y):
    # Choose the correct assertion below

A assert x * y == 6

B assert x + y == 6

C assert x - y == 6

D assert x / y == 6

💡 Hint

Product means multiplication

The test checks if multiplying x and y equals 6. Only option A uses multiplication correctly.

🔧 Debug

advanced

Identify the error in parametrize usage

What error will this pytest code raise when run?

PyTest

import pytest

@pytest.mark.parametrize('x,y', [(1, 2), (3, 4)])
def test_values(x, y):
    assert x < y

A TypeError: cannot unpack non-iterable int object

B No error, test runs successfully

C AssertionError: test fails

D SyntaxError: invalid syntax in parametrize decorator

💡 Hint

Check the format of the list passed to parametrize

The list should contain tuples of two values, but here it contains integers, so unpacking fails.

🧠 Conceptual

advanced

Purpose of @pytest.mark.parametrize

What is the main purpose of using @pytest.mark.parametrize in pytest tests?

A To mark tests as expected to fail

B To skip tests conditionally based on input

C To run the same test function multiple times with different input values

D To group multiple tests into one test suite

💡 Hint

Think about repeating tests with different data

Parametrize allows running one test function many times with different inputs to check multiple cases easily.

❓ framework

expert

Combining parametrize with fixtures

Given this pytest code, what will be the output when running the test?

PyTest

import pytest

@pytest.fixture
def base_value():
    return 10

@pytest.mark.parametrize('increment', [1, 2])
def test_increment(base_value, increment):
    assert base_value + increment in [11, 12]

A Fixture not found error

B First test passes, second test fails

C Both tests fail

D Both tests pass

💡 Hint

Check the sum of base_value and increment for each param

The fixture returns 10. Adding increments 1 and 2 gives 11 and 12, both in the allowed list, so both tests pass.