Parameterizing Tests in Pytest

A testing framework in Python that is used to write API test cases is called Pytest is distinct instances of input and output are possible for a function. In such a case, it is crucial to test the function for all the inputs and outputs. This can be done using the parametrize function in Pytest.

Parameterizing Tests in Pytest

Syntax:

@pytest.mark.parametrize(“input, output”,[(input_1, output_1),(input_2, output_2),(input_3, output_3),(input_4, input_4)])

Here,

• input, output: These are the parameters to be passed to the function.
• input_1, input_2, input_3, input_4: These are the input values for which the function needs to be tested.
• output_1, output_2, output_3, output_4: These are the output values predicted for the specific inputs.

Example 1:

In this example we have created a program, that has two test cases, test_floor and test_square_root. For both of the test cases, we have passed four inputs each to test using parametrize function.

Python3

# Importing the math and Pytest libraries
import math
import pytest

# Creating first test case
@pytest.mark.parametrize("input, output", [(5.234, 5), (9.99, 10), (0.456, 0), (7.905, 7)])
def test_floor(input, output):
   assert output==math.floor(input)

# Creating second test case
@pytest.mark.parametrize("val, result", [(8, 60), (1, 1), (3, 10), (5, 25)])
def test_square_root(val, result):
   assert result==math.sqrt(val)

Output:

Now, we will run the following command in terminal.

pytest main.py

Example 2:

In this example, we have created a program that has two test cases test_remove_G and test_remove_e. In both the test cases, we have passed two inputs each to test for a specific output.

Python3

# Importing the Pytest library
import pytest

# Creating first test case
@pytest.mark.parametrize("input, output",
                         [("Geeks For Geeks",
                           "eeks For eeks"),
                           ("Go Air", "o Air"), ])
def test_remove_G(input, output):
    assert input.replace('G','')==output

# Creating second test case
@pytest.mark.parametrize("input, output",
                         [("Geeks For Geeks",
                             "Gaks For Gaks"),
                            ("Engineer", "Enginr"), ])
def test_e(input, output):
    assert input.replace('e','')==output

Output:

Now, we will run the following command in terminal.

pytest main.py

Conclusion

It is necessary for a tester to test each scenario possible, thus he need to test the test case for more than one input. I hope the above article will help you to test your test cases for more than one input, i.e., parametrizing tests. Parametrizing tests is indeed a crucial aspect of software testing. It allows testers to validate the behavior of a piece of software under various input conditions. Here, we will explore the concept of parametrized tests and how to implement them to ensure thorough and efficient testing.