Combining multiple parametrize decorators in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of combined parametrize decorators in pytest

What is the total number of test cases executed by pytest for the following test function?

PyTest

import pytest

@pytest.mark.parametrize('x', [1, 2])
@pytest.mark.parametrize('y', [3, 4, 5])
def test_sum(x, y):
    assert (x + y) > 0

A 3

B 6

C 5

D 2

💡 Hint

Remember that multiple parametrize decorators multiply the number of test cases.

pytest runs the test for every combination of parameters. Here, x has 2 values and y has 3 values, so total tests = 2 * 3 = 6.

❓ assertion

intermediate

Assertion behavior with combined parametrize decorators

Given the following test, which assertion will fail during pytest execution?

PyTest

import pytest

@pytest.mark.parametrize('a', [0, 1])
@pytest.mark.parametrize('b', [2, 3])
def test_multiply(a, b):
    assert (a * b) != 0

A a=1, b=3

B a=0, b=2

C a=1, b=2

D a=0, b=3

💡 Hint

Check when the product of a and b equals zero.

The assertion fails whenever a=0, since 0 * b = 0. This happens for a=0, b=2 (B) and a=0, b=3 (D).

🔧 Debug

advanced

Identify the error in combined parametrize usage

What error will pytest raise when running this test code?

PyTest

import pytest

@pytest.mark.parametrize('x', [1, 2])
@pytest.mark.parametrize('x', [3, 4])
def test_values(x):
    assert x > 0

A ValueError: conflicting parameter names

B TypeError: multiple values for argument 'x'

C SyntaxError: duplicate decorator parameter

D pytest collects 4 tests and runs successfully

💡 Hint

Consider how pytest handles multiple parametrize decorators with the same argument name.

pytest raises ValueError because the same argument 'x' is parametrized in multiple decorators (parameter names must be disjoint across decorators).

🧠 Conceptual

advanced

Order of parameter combinations with multiple parametrize decorators

In pytest, when combining multiple parametrize decorators, which statement about the order of test case generation is true?

A The outer decorator's parameters vary faster than the inner decorator's parameters.

B Only the first decorator's parameters are used; others are ignored.

C The inner decorator's parameters vary faster than the outer decorator's parameters.

D Parameters vary randomly regardless of decorator order.

💡 Hint

Think about nested loops and which loop runs inside the other.

pytest applies parametrize decorators like nested loops: the inner decorator's parameters vary faster (like the inner loop).

❓ framework

expert

Combining parametrize with indirect fixture in pytest

Given the following pytest code, how many test cases will be executed?

PyTest

import pytest

@pytest.fixture

def data(request):
    return request.param * 2

@pytest.mark.parametrize('data', [1, 2], indirect=True)
@pytest.mark.parametrize('flag', [True, False])
def test_indirect(data, flag):
    assert isinstance(data, int) and isinstance(flag, bool)

A 1

B 2

C 3

D 4

💡 Hint

Consider how indirect parametrize and multiple decorators combine.

The test runs for each combination of data (indirectly parametrized with 2 values) and flag (2 values), total 2*2=4 tests.