Testing multiple exceptions in PyTest

Introduction

We test multiple exceptions to make sure our code handles different errors correctly. This helps catch bugs and improves program reliability.

When a function can raise different errors depending on input.

When you want to confirm your code raises the right error for wrong data.

When testing error handling in user input validation.

When checking that your program fails safely under various bad conditions.

Syntax

PyTest

import pytest

with pytest.raises((ExceptionType1, ExceptionType2)):
    # code that should raise one of the exceptions

You list exceptions inside a tuple to check for multiple possible errors.

The test passes if any one of the exceptions is raised.

Examples

This test passes because dividing by zero raises ZeroDivisionError, which is in the tuple.

PyTest

import pytest

def test_divide():
    with pytest.raises((ZeroDivisionError, TypeError)):
        result = 10 / 0  # raises ZeroDivisionError

This test passes because adding string and int raises TypeError, which is in the tuple.

PyTest

import pytest

def test_add():
    with pytest.raises((ZeroDivisionError, TypeError)):
        result = 'a' + 1  # raises TypeError

Sample Program

This test checks that risky_operation raises either ZeroDivisionError or TypeError for bad inputs. It also confirms normal input works.

PyTest

import pytest

def risky_operation(value):
    if value == 0:
        raise ZeroDivisionError("Cannot divide by zero")
    elif not isinstance(value, int):
        raise TypeError("Value must be an integer")
    return 10 / value

def test_risky_operation():
    with pytest.raises((ZeroDivisionError, TypeError)):
        risky_operation(0)  # should raise ZeroDivisionError
    with pytest.raises((ZeroDivisionError, TypeError)):
        risky_operation('a')  # should raise TypeError
    # This call should NOT raise an exception
    assert risky_operation(2) == 5.0

Important Notes

Always use a tuple to list multiple exceptions inside pytest.raises().

If the code does not raise any of the listed exceptions, the test fails.

Use this to keep tests simple when multiple errors are acceptable.

Summary

Use pytest.raises() with a tuple to test multiple exceptions.

The test passes if any one of the exceptions is raised.

This helps verify your code handles different error cases properly.