monkeypatch.delattr in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output after monkeypatch.delattr removes an attribute?

Consider the following code using pytest's monkeypatch.delattr. What will be the output of the test function?

PyTest

class MyClass:
    def method(self):
        return "original"

def test_method(monkeypatch):
    obj = MyClass()
    monkeypatch.delattr(obj, "method")
    try:
        result = obj.method()
    except AttributeError:
        result = "AttributeError"
    print(result)

A AttributeError

B original

C TypeError

D None

💡 Hint

Think about what happens when you remove an attribute and then try to access it.

The monkeypatch.delattr removes the 'method' attribute from the instance 'obj'. When calling obj.method(), Python cannot find the method and raises AttributeError.

❓ assertion

intermediate

Which assertion correctly verifies that monkeypatch.delattr removed an attribute?

Given an object 'obj' with attribute 'attr', and after monkeypatch.delattr(obj, 'attr'), which assertion correctly checks that 'attr' is removed?

A assert obj.attr == ''

B assert hasattr(obj, 'attr') is False

C assert obj.attr is None

D assert hasattr(obj, 'attr') is True

💡 Hint

Use hasattr to check if an attribute exists.

After monkeypatch.delattr removes 'attr', hasattr(obj, 'attr') returns False. So asserting it is False confirms removal.

🔧 Debug

advanced

Why does monkeypatch.delattr fail to remove a class attribute when called on an instance?

Given this code: class MyClass: attr = 5 obj = MyClass() monkeypatch.delattr(obj, 'attr') Why does obj.attr still return 5 after delattr?

A Because monkeypatch.delattr cannot remove attributes from any object

B Because delattr requires the attribute name as bytes, not string

C Because attr is a private attribute and cannot be removed

D Because delattr on instance only removes instance attributes, not class attributes

💡 Hint

Think about where the attribute is stored: instance or class?

Attributes defined on the class are not stored on the instance. monkeypatch.delattr called on the instance removes only instance attributes, so class attributes remain accessible.

❓ framework

advanced

How does monkeypatch.delattr behave with the 'raising' parameter set to False?

What happens when you call monkeypatch.delattr(obj, 'missing_attr', raising=False) if 'missing_attr' does not exist on obj?

A It silently does nothing without raising an error

B It raises AttributeError immediately

C It removes all attributes from obj

D It creates 'missing_attr' with value None

💡 Hint

Check the effect of the 'raising' flag in monkeypatch.delattr.

With raising=False, monkeypatch.delattr does not raise an error if the attribute does not exist; it silently skips removal.

🧠 Conceptual

expert

What is the main advantage of using monkeypatch.delattr in tests?

Why would a tester prefer monkeypatch.delattr over manually deleting attributes in test setup?

A It improves test performance by caching attributes

B It permanently deletes the attribute from the class or instance

C It automatically restores the attribute after the test ends

D It converts attributes to private to prevent access

💡 Hint

Think about test isolation and cleanup.

monkeypatch.delattr removes attributes temporarily during a test and restores them after, ensuring tests do not affect each other.