pytest.raises context manager - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of pytest.raises with ZeroDivisionError

What will be the output of this test code when run with pytest?

PyTest

import pytest

def test_division():
    with pytest.raises(ZeroDivisionError):
        x = 1 / 0
    print("Test passed")

A No output because test is skipped

B ZeroDivisionError is raised and test fails

C SyntaxError due to incorrect pytest usage

D Test passed

💡 Hint

pytest.raises expects the code inside to raise the specified error to pass.

The code inside the with block raises ZeroDivisionError, which pytest.raises catches, so the test passes and prints 'Test passed'.

❓ assertion

intermediate

Correct assertion to check exception message with pytest.raises

Which option correctly asserts that a ValueError with message 'invalid input' is raised?

PyTest

import pytest

def func():
    raise ValueError('invalid input')

def test_func():
    with pytest.raises(ValueError) as excinfo:
        func()
    # Which assertion below is correct?

A assert excinfo.value.message == 'invalid input'

B assert excinfo.message == 'invalid input'

C assert 'invalid input' in str(excinfo.value)

D assert excinfo == 'invalid input'

💡 Hint

Exception message is accessed via str(excinfo.value).

The exception message is stored in excinfo.value and converted to string with str(). The other options access non-existent attributes.

🔧 Debug

advanced

Why does this pytest.raises test fail?

Given this test code, why does pytest report a failure?

PyTest

import pytest

def test_error():
    with pytest.raises(ValueError):
        x = int('abc')
    with pytest.raises(TypeError):
        x = int('abc')

A The first with block does not raise any error

B The second with block expects TypeError but int('abc') raises ValueError

C pytest.raises cannot be used twice in one test

D int('abc') raises SyntaxError, not ValueError or TypeError

💡 Hint

Check the actual error type raised by int('abc').

int('abc') raises ValueError, so the first with block passes but the second expects TypeError and fails.

🧠 Conceptual

advanced

Behavior of pytest.raises when no exception is raised

What happens if the code inside a pytest.raises context manager does NOT raise the expected exception?

A The test fails with Failed: DID NOT RAISE <ExceptionType>

B The test passes silently

C pytest.raises raises a SyntaxError

D The test is skipped automatically

💡 Hint

pytest.raises expects an exception to be raised inside the block.

If no exception is raised, pytest.raises causes the test to fail with a message indicating the expected exception was not raised.

❓ framework

expert

Using pytest.raises to test multiple exception types

Which option correctly tests that a function raises either ValueError or TypeError using pytest.raises?

A

with pytest.raises((ValueError, TypeError)):
    func()

B

with pytest.raises(ValueError | TypeError):
    func()

C

with pytest.raises(ValueError) and pytest.raises(TypeError):
    func()

D

with pytest.raises(ValueError) or pytest.raises(TypeError):
    func()

💡 Hint

pytest.raises accepts a tuple of exception types to check multiple exceptions.

pytest.raises accepts a tuple of exceptions to check if any of them is raised. The other options are invalid syntax or logic.