Start Here
Learn Python

Start Learning
Your Learning Plan →Your personalized Python learning plan Python Tutorials →In-depth articles and video courses Learning Paths →Guided study plans for accelerated learning

Practice
Quizzes & Exercises →Check your learning progress Browse Topics →Focus on a specific area or skill level Reference →Concise definitions for common Python terms

Get Help
Code Mentor →BetaPersonalized code assistance & learning tools Office Hours →Live Q&A calls with Python experts Community Chat →Learn with other Pythonistas

Go Deeper
Live Courses →Live, instructor-led Python courses Books →Round out your knowledge and learn offline Podcast →Hear what’s new in the world of Python

Unlock All Content and Become a Python Expert →Get unlimited access to all Real Python has to offer

Unlock All Content →Become a Python Expert
More
Learner Stories Python Newsletter Python Job Board Meet the Team Become a Contributor

Search

/

Join
Sign‑In

Loading exercise...

Exercise: Constrain a Mock With spec

Lee Gaines

Exploring unittest.mock in Python Lee Gaines 08:00

Recommended Tutorial Course Slides (.pdf) Sample Code (.zip) Ask a Question

Discussion

Become a Member to join the conversation.

Course Contents

Overview

94%

Exploring unittest.mock in Python (Overview) 01:08

What Is Mocking? 01:59

The Mock Library 00:43

Mock Objects 03:22

Lazy Attributes and Methods 02:40

Assertions 05:02

Associated Attributes 03:17

Exercise: Inspect How a Mock Was Called 08:00

Return Value (Part 1) 03:40

Return Value (Part 2) 03:55

unittest Example 05:34

What Is a Side Effect? 01:45

Side Effects: Setting Up 02:36

Side Effects: Troubleshooting 02:39

Side Effects: Testing 03:05

Side Effects: Another Test 02:16

Side Effects: Advanced Test (Part 1) 03:37

Side Effects: Advanced Test (Part 2) 04:15

Side Effects as an Iterable (Part 1) 02:33

Side Effects as an Iterable (Part 2) 06:58

Exercise: Make a Mock Raise an Exception 08:00

Configure Mocks (Part 1) 03:15

Configure Mocks (Part 2) 01:41

Exercise: Build a Fake API Response 08:00

What Is patch()? 01:33

patch() as Decorator 04:44

patch() as Context Manager 01:11

patch.object() as Context Manager 03:47

patch.object() as Decorator 01:18

Exercise: Patch a Dependency in a Test 08:00

Common Problems With Mocking 02:08

spec List 03:05

spec Module 01:55

Exercise: Constrain a Mock With spec 08:00

Understanding the Python Mock Object Library (Quiz) 08:00

Exploring unittest.mock in Python (Summary) 01:02

© 2012–2026 Real Python ⋅ Privacy Policy