Testing multiple exceptions in PyTest - Test Execution Trace

Test Overview

This test checks that a function raises either a ValueError or a TypeError when given invalid inputs. It verifies that the function correctly handles multiple error cases.

Test Code - pytest

PyTest

import pytest

def process_value(value):
    if not isinstance(value, int):
        raise TypeError("Value must be an integer")
    if value < 0:
        raise ValueError("Value must be non-negative")
    return value * 2

def test_process_value_exceptions():
    with pytest.raises((ValueError, TypeError)) as exc_info:
        process_value(-1)  # Should raise ValueError
    assert isinstance(exc_info.value, ValueError)

    with pytest.raises((ValueError, TypeError)) as exc_info:
        process_value('a')  # Should raise TypeError
    assert isinstance(exc_info.value, TypeError)

Execution Trace - 8 Steps

Step	Action	System State	Assertion	Result
1	Test starts	pytest test runner initialized	-	PASS
2	Calls process_value(-1)	Function receives -1 as input	Check if ValueError or TypeError is raised	PASS
3	process_value raises ValueError("Value must be non-negative")	Exception raised inside function	Exception type is ValueError	PASS
4	Assertion confirms exception is ValueError	Exception captured in exc_info	assert isinstance(exc_info.value, ValueError)	PASS
5	Calls process_value('a')	Function receives string 'a' as input	Check if ValueError or TypeError is raised	PASS
6	process_value raises TypeError("Value must be an integer")	Exception raised inside function	Exception type is TypeError	PASS
7	Assertion confirms exception is TypeError	Exception captured in exc_info	assert isinstance(exc_info.value, TypeError)	PASS
8	Test ends	All assertions passed	-	PASS

Failure Scenario

Failing Condition: Function does not raise the expected exceptions for invalid inputs

Execution Trace Quiz - 3 Questions

What exception does process_value(-1) raise in this test?

A TypeError

B IndexError

C ValueError

D No exception

Key Result

Using pytest.raises with a tuple allows testing that a function raises any one of multiple expected exceptions, making tests concise and clear.