Testing multiple exceptions in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of pytest test with multiple exception checks

What is the test result when running this pytest test function that checks for multiple exceptions?

PyTest

import pytest

def func(x):
    if x == 0:
        raise ValueError("Zero not allowed")
    elif x == 1:
        raise TypeError("One is wrong type")
    return x

def test_func_exceptions():
    with pytest.raises(ValueError):
        func(0)
    with pytest.raises(TypeError):
        func(1)

A Test passes but does not catch any exceptions.

B Test passes with both exceptions correctly caught.

C Test fails because only the first exception is caught; second raises an error.

D Test fails due to a SyntaxError in the test code.

💡 Hint

pytest.raises can be used multiple times in one test function to check different exceptions.

The test calls func with 0 and 1 inside separate pytest.raises blocks, so both exceptions are caught and the test passes.

❓ assertion

intermediate

Correct assertion to check multiple exceptions in pytest

Which assertion correctly tests that a function raises either ValueError or TypeError when called with certain inputs?

PyTest

def func(x):
    if x == 0:
        raise ValueError("Zero not allowed")
    elif x == 1:
        raise TypeError("One is wrong type")
    return x

A

with pytest.raises(ValueError):
    func(0)
with pytest.raises(TypeError):
    func(1)

B

with pytest.raises((ValueError, TypeError)):
    func(0)
    func(1)

C

with pytest.raises(ValueError) or pytest.raises(TypeError):
    func(0)
    func(1)

D assert func(0) raises ValueError and func(1) raises TypeError

💡 Hint

Use separate pytest.raises blocks for different exceptions.

Option A correctly uses separate pytest.raises blocks to check each exception individually. Option A incorrectly tries to catch both exceptions in one block but calls both functions inside it, which will fail on the first exception and not reach the second call.

🔧 Debug

advanced

Debug why second exception test is not reached

Why does the second exception test not run in this pytest code?

PyTest

import pytest

def func(x):
    if x == 0:
        raise ValueError("Zero not allowed")
    elif x == 1:
        raise TypeError("One is wrong type")
    return x

def test_func():
    with pytest.raises((ValueError, TypeError)):
        func(0)
        func(1)

A Because the test function is missing a return statement.

B Because pytest.raises cannot catch multiple exceptions in one block.

C Because func(1) does not raise any exception.

D Because func(0) raises ValueError and exits the with block before func(1) is called.

💡 Hint

Consider how exceptions interrupt code flow inside a with block.

When func(0) raises ValueError, the with block exits immediately, so func(1) is never called. To test both exceptions, separate with blocks are needed.

❓ framework

advanced

Best pytest pattern to test multiple exceptions separately

Which pytest test function correctly tests that func raises ValueError for 0 and TypeError for 1, ensuring both exceptions are tested independently?

PyTest

def func(x):
    if x == 0:
        raise ValueError("Zero not allowed")
    elif x == 1:
        raise TypeError("One is wrong type")
    return x

A

def test_func():
    with pytest.raises(ValueError):
        func(0)
    with pytest.raises(TypeError):
        func(1)

B

def test_func():
    with pytest.raises((ValueError, TypeError)):
        func(0)
        func(1)

C

def test_func():
    assert func(0) raises ValueError
    assert func(1) raises TypeError

D

def test_func():
    try:
        func(0)
    except ValueError:
        pass
    try:
        func(1)
    except TypeError:
        pass

💡 Hint

Use separate with blocks for each exception test.

Option A uses separate pytest.raises blocks, which is the recommended way to test multiple exceptions independently. Option A fails to test the second call because the first exception interrupts the block. Option A is invalid syntax. Option A does not use pytest's assertion mechanism and will not fail the test if exceptions are not raised.

🧠 Conceptual

expert

Why separate pytest.raises blocks are preferred for multiple exceptions

Why is it better to use separate pytest.raises blocks when testing multiple exceptions in one test function?

A Because combining exceptions in one block causes syntax errors.

B Because pytest.raises only supports one exception type per test file.

C Because each pytest.raises block stops execution on exception, so separate blocks ensure all exceptions are tested.

D Because pytest.raises automatically retries the block until all exceptions occur.

💡 Hint

Think about how exceptions affect code flow inside a with block.

Each pytest.raises block exits as soon as the expected exception is raised, so if multiple exceptions are tested in one block, only the first is caught. Separate blocks allow testing each exception independently.