Multiple parameters in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of pytest with multiple parameters

What will be the output when running this pytest code with multiple parameters?

PyTest

import pytest

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

A 4 tests run, all pass

B 2 tests run, all pass

C 2 tests run, some fail

D 4 tests run, some fail

💡 Hint

Remember how pytest combines multiple parametrize decorators.

pytest runs the test for all combinations of parameters from multiple @pytest.mark.parametrize decorators, so 2 values for x and 2 for y produce 4 tests. All pass because all sums are greater than 3.

❓ assertion

intermediate

Correct assertion for multiple parameters

Which assertion correctly verifies that the product of parameters a and b is always even in this test?

PyTest

import pytest

@pytest.mark.parametrize("a", [1, 2])
@pytest.mark.parametrize("b", [2, 3])
def test_product_even(a, b):
    # Choose the correct assertion below

A assert (a - b) % 2 == 0

B assert (a + b) % 2 == 0

C assert (a * b) % 2 == 1

D assert (a * b) % 2 == 0

💡 Hint

Check which operation and condition ensures even product.

The product is even if divisible by 2, so (a * b) % 2 == 0 is the correct assertion. Other options check sum or difference or odd product.

🔧 Debug

advanced

Identify the error in multiple parameter test

What error will this pytest code raise when run?

PyTest

import pytest

@pytest.mark.parametrize("x, y", [(1, 2), (3, 4)])
@pytest.mark.parametrize("z", [5, 6])
def test_values(x, y, z):
    assert x + y + z > 0

A pytest runs 4 tests, all pass

B TypeError: test_values() missing 1 required positional argument: 'z'

C pytest runs 6 tests, all pass

D ValueError: too many values to unpack

💡 Hint

Check how pytest combines multiple parametrize decorators with multiple arguments.

pytest combines parameters by Cartesian product. The first parametrize provides 2 tuples (x,y), second provides 2 values for z, so 2*2=4 tests. But since x,y are grouped, and z separate, total tests are 4. All sums are positive, so all pass.

❓ locator

advanced

Best locator for multiple parameter test cases

In a test report, which locator best identifies a test case with parameters x=2 and y=3 in pytest?

A test_sum(x=2,y=3)

B test_sum[2-3]

C test_sum_2_3

D test_sum(2,3)

💡 Hint

pytest uses a specific format for parameterized test IDs.

pytest shows parameterized test IDs in the format test_name[param1-param2], so test_sum[2-3] is the correct locator. Others are not standard pytest locators.

❓ framework

expert

Understanding parameter combination in pytest

Given these decorators, how many total test cases will pytest generate?

PyTest

import pytest

@pytest.mark.parametrize("a", [1, 2])
@pytest.mark.parametrize("b, c", [(3, 4), (5, 6)])
@pytest.mark.parametrize("d", [7])
def test_func(a, b, c, d):
    pass

A 8 tests

B 2 tests

C 4 tests

D 16 tests

💡 Hint

Multiply the number of values in each parametrize considering grouping.

pytest combines parameters by Cartesian product. a has 2 values, (b,c) has 2 tuples, d has 1 value. Total tests = 2 * 2 * 1 = 4 tests. But pytest applies parametrize decorators bottom-up, so the total is 2 (a) * 2 (b,c) * 1 (d) = 4 tests.