Testing multiple exceptions in PyTest - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to test if a ValueError is raised.

PyTest

import pytest

def test_value_error():
    with pytest.raises([1]):
        int('abc')

Drag options to blanks, or click blank then click option'

ATypeError

BValueError

CKeyError

DIndexError

Attempts:

3 left

💡 Hint

Common Mistakes

Using TypeError instead of ValueError

Not using pytest.raises context manager

The pytest.raises() function expects the exception type to check. Here, int('abc') raises a ValueError.

2fill in blank

medium

Complete the code to test if a ZeroDivisionError is raised.

PyTest

import pytest

def test_zero_division():
    with pytest.raises([1]):
        result = 10 / 0

Drag options to blanks, or click blank then click option'

AValueError

BOverflowError

CArithmeticError

DZeroDivisionError

Attempts:

3 left

💡 Hint

Common Mistakes

Using ValueError or ArithmeticError instead of ZeroDivisionError

Not using the context manager correctly

Dividing by zero raises a ZeroDivisionError. The test checks for this specific exception.

3fill in blank

hard

Fix the error in the test to correctly check for multiple exceptions.

PyTest

import pytest

def test_multiple_exceptions():
    with pytest.raises(([1])):
        int('abc')
        result = 10 / 0

Drag options to blanks, or click blank then click option'

AValueError, ZeroDivisionError

BValueError ZeroDivisionError

C[ValueError, ZeroDivisionError]

D['ValueError', 'ZeroDivisionError']

Attempts:

3 left

💡 Hint

Common Mistakes

Using a list instead of a tuple

Passing exception names as strings

To test multiple exceptions, pass a tuple of exception types without brackets or quotes around the types.

4fill in blank

hard

Fill both blanks to test if either KeyError or IndexError is raised.

PyTest

import pytest

def test_key_or_index_error():
    with pytest.raises(([1], [2])):
        d = {}
        _ = d['missing_key']

Drag options to blanks, or click blank then click option'

AKeyError

BIndexError

CValueError

DTypeError

Attempts:

3 left

💡 Hint

Common Mistakes

Using ValueError or TypeError instead

Not passing a tuple of exceptions

The test checks for either KeyError or IndexError. Both are valid exceptions to catch here.

5fill in blank

hard

Fill all three blanks to test if either AttributeError, TypeError, or ValueError is raised.

PyTest

import pytest

def test_multiple_exceptions_complex():
    with pytest.raises(([1], [2], [3])):
        obj = None
        obj.some_method()

Drag options to blanks, or click blank then click option'

AAttributeError

BTypeError

CValueError

DKeyError

Attempts:

3 left

💡 Hint

Common Mistakes

Including KeyError which is unrelated here

Not using a tuple for multiple exceptions

This test expects one of three exceptions: AttributeError if the method does not exist, TypeError if the call is invalid, or ValueError for invalid values.

Practice

1. What does pytest.raises((ValueError, TypeError)) do in a test?

easy

A. It passes if either ValueError or TypeError is raised during the test.

B. It passes only if both ValueError and TypeError are raised together.

C. It fails if any exception is raised during the test.

D. It ignores exceptions and always passes the test.

Solution

1. Step 1: Understand pytest.raises with tuple

   Using a tuple inside pytest.raises means the test expects any one of those exceptions.

2. Step 2: Effect on test pass/fail

   If the code raises either ValueError or TypeError, the test passes. If no exception or a different exception is raised, it fails.

3. Final Answer:

   It passes if either ValueError or TypeError is raised during the test. -> Option A

4. Quick Check:

   pytest.raises with tuple = any exception in tuple passes [OK]

Hint: Tuple in pytest.raises means any listed exception passes [OK]

Common Mistakes:

• Thinking both exceptions must be raised simultaneously
• Assuming it passes without exceptions
• Confusing tuple with multiple separate pytest.raises calls

2. Which of the following is the correct syntax to test for multiple exceptions in pytest?

easy

A. with pytest.raises{ValueError, TypeError}:

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

C. with pytest.raises([ValueError, TypeError]):

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

Solution

1. Step 1: Recall pytest.raises syntax

   pytest.raises expects a single exception or a tuple of exceptions inside parentheses.

2. Step 2: Identify correct tuple syntax

   Only with pytest.raises((ValueError, TypeError)): uses a tuple (parentheses with comma-separated exceptions) correctly.

3. Final Answer:

   with pytest.raises((ValueError, TypeError)): -> Option D

4. Quick Check:

   Tuple syntax with parentheses and comma = correct [OK]

Hint: Use parentheses and comma for multiple exceptions in pytest.raises [OK]

Common Mistakes:

• Using multiple arguments without tuple
• Using list brackets instead of tuple
• Using curly braces which are invalid syntax

3. What will be the result of this pytest test?

def test_func():
    with pytest.raises((KeyError, IndexError)):
        d = {'a': 1}
        value = d['b']

medium

A. Test fails due to syntax error.

B. Test passes because KeyError is raised.

C. Test passes because IndexError is raised.

D. Test fails because no exception is raised.

Solution

1. Step 1: Identify exception raised by d['b']

   Accessing a missing key in a dictionary raises KeyError.

2. Step 2: Check if KeyError is in the tuple

   KeyError is in (KeyError, IndexError), so pytest.raises expects it and test passes.

3. Final Answer:

   Test passes because KeyError is raised. -> Option B

4. Quick Check:

   Missing dict key = KeyError, in tuple = pass [OK]

Hint: Missing dict key raises KeyError, matches tuple exceptions [OK]

Common Mistakes:

• Thinking IndexError is raised instead
• Assuming no exception is raised
• Confusing KeyError with ValueError

4. What will be the result of this pytest test?

def test_divide():
    with pytest.raises((ZeroDivisionError, ValueError)):
        result = 10 / 0
        int('abc')

medium

A. The test will pass because ZeroDivisionError is raised first.

B. The test will fail because the second line after exception is unreachable.

C. The test will fail because only ZeroDivisionError is raised, not ValueError.

D. The test will fail due to syntax error in pytest.raises.

Solution

1. Step 1: Analyze exception flow in with block

   ZeroDivisionError occurs at 10 / 0, so the next line int('abc') is never executed.

2. Step 2: Understand pytest.raises behavior

   ZeroDivisionError is in the expected tuple, so test passes. ValueError is unreachable.

3. Step 3: Confirm test outcome

   Since a matching exception (ZeroDivisionError) is raised first, the test passes.

4. Final Answer:

   The test will pass because ZeroDivisionError is raised first. -> Option A

5. Quick Check:

   Exception stops code, later lines unreachable; matching exc = pass [OK]

Hint: Exception stops code; lines after are not run [OK]

Common Mistakes:

• Thinking both exceptions must be raised simultaneously
• Thinking test fails due to syntax
• Ignoring unreachable code after exception

5. You want to test a function that can raise either IndexError or KeyError depending on input. Which pytest test code correctly checks both exceptions in one test?

hard

A. def test_func():
with pytest.raises(IndexError, KeyError):
func_that_raises()

B. def test_func():
with pytest.raises([IndexError, KeyError]):
func_that_raises()

C. def test_func():
with pytest.raises((IndexError, KeyError)):
func_that_raises()

D. def test_func():
with pytest.raises({IndexError, KeyError}):
func_that_raises()

Solution

1. Step 1: Recall correct syntax for multiple exceptions

   pytest.raises expects a tuple of exceptions to check multiple exceptions in one block.

2. Step 2: Identify correct tuple usage

   def test_func(): with pytest.raises((IndexError, KeyError)): func_that_raises() uses a tuple (parentheses with comma-separated exceptions), which is correct syntax.

3. Step 3: Check other options

   Options A, B, and D use invalid syntax: multiple arguments without tuple, list, or set instead of tuple.

4. Final Answer:

   def test_func(): with pytest.raises((IndexError, KeyError)): func_that_raises() -> Option C

5. Quick Check:

   Tuple of exceptions in pytest.raises = correct [OK]

Hint: Use tuple (parentheses, commas) for multiple exceptions in pytest.raises [OK]

Common Mistakes:

• Passing exceptions as separate arguments
• Using list or set instead of tuple
• Forgetting parentheses around exceptions