API client testing in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this pytest API client test?

Consider this pytest test function that uses a mock API client to test a GET request response status code.

PyTest

import pytest
from unittest.mock import Mock

class APIClient:
    def get(self, url):
        # Simulate a real HTTP GET request
        return Mock(status_code=200)

def test_get_status_code():
    client = APIClient()
    response = client.get('/resource')
    assert response.status_code == 200
    print('Test passed')

A AttributeError

B AssertionError

C Test passed

D SyntaxError

💡 Hint

Look at the mocked response status_code and the assertion.

The mock response has status_code 200, which matches the assertion, so the test passes and prints 'Test passed'.

❓ assertion

intermediate

Which assertion correctly verifies JSON response content?

You receive this JSON response from an API client: {"user": "alice", "active": true}. Which pytest assertion correctly checks that the user is 'alice' and active is True?

A assert response.json()['user'] == 'alice' and response.json()['active'] is True

B assert response.json()['user'] = 'alice' and response.json()['active'] == True

C assert response.json().user == 'alice' and response.json().active == True

D assert response.json()['user'] == alice and response.json()['active'] == true

💡 Hint

Remember how to access dictionary keys and compare values in Python.

Option A uses correct dictionary key access and comparison operators. Option A uses assignment (=) instead of comparison (==). Option A tries attribute access on a dict, which raises an error. Option A uses unquoted strings and lowercase true, which are invalid in Python.

❓ locator

advanced

Which locator correctly mocks an API client method for a POST request?

You want to mock the post method of an API client instance client to return a response with status code 201. Which option correctly sets this up using unittest.mock?

A client.post = Mock(return_value=Mock(status_code=201))

B client.post.return_value.status_code = 201

C Mock(client.post, return_value=Mock(status_code=201))

D client.post = Mock(status_code=201)

💡 Hint

Think about how to assign a mock method that returns a mock response.

Option A correctly assigns a Mock to client.post that returns another Mock with status_code 201. Option A tries to set return_value on a method that may not be mocked yet. Option A uses Mock incorrectly as a function. Option A assigns a Mock with status_code attribute directly, but not as a callable method.

🔧 Debug

advanced

Why does this pytest API test fail with AttributeError?

Examine this test code snippet:

def test_api_call(client):
    response = client.get('/data')
    assert response.status == 200

The test fails with AttributeError: 'Mock' object has no attribute 'status'. Why?

A The assertion syntax is incorrect.

B The response object uses 'status_code' attribute, not 'status'.

C The client.get method is not mocked properly.

D The URL '/data' is invalid causing no response.

💡 Hint

Check the attribute names commonly used in HTTP response objects.

HTTP response objects typically have a 'status_code' attribute, not 'status'. Accessing 'status' causes AttributeError.

❓ framework

expert

Which pytest fixture setup ensures isolated API client tests?

You want to write pytest tests for an API client where each test gets a fresh client instance with a mocked get method returning status 200. Which fixture setup is best?

A

@pytest.fixture(scope='session')
def client():
    client = APIClient()
    client.get = Mock(return_value=Mock(status_code=200))
    return client

B

@pytest.fixture(scope='module')
def client():
    client = APIClient()
    client.get = Mock(return_value=Mock(status_code=200))
    return client

C

@pytest.fixture(autouse=True)
def client():
    client = APIClient()
    client.get = Mock(return_value=Mock(status_code=200))
    return client

D

@pytest.fixture
def client():
    client = APIClient()
    client.get = Mock(return_value=Mock(status_code=200))
    return client

💡 Hint

Consider fixture scope and test isolation.

Option D creates a new client instance per test (default function scope), ensuring isolation. Options B, C, and D use broader scopes or autouse, which may share the client across tests, risking state leakage.