Build your own test framework
Build your own test framework
in JavaScript
About the Book
A build-your-own test framework adventure. Learn how a JavaScript test framework is put together, by making use of the Node API including ES6 modules, NPM packaging, ES6 proxy objects, and more.
Test frameworks like Jest, Mocha and Jasmine are well-understood by the JavaScript community. Other languages, like Ruby, have even more advanced techniques--such as shared examples and tagged tests--that aren't yet commonly available in JavaScript test runners.
This book walks you through the development of the concise-test NPM package, a fully-featured test framework written with conciseness in mind.
By following the walkthrough you'll discover a number of different design techniques and programming devices, and learn about the Node API and broaden your testing knowledge.
This book isn't for beginner programmers, but will be useful read to anyone looking to deepen their understanding of the JavaScript language and automated testing.
About the Author
Table of Contents
-
- About the author
- Changelog
- Preface
-
How to use this book
- In a workshop setting
- Tools you’ll need
- Skills you’ll need
- Feedback
- Please share with your friends and followers
-
Introduction
- An overview of this book
- What is an automated unit test framework?
- What will we build in this book?
- We’re building a spike
- Let’s get started: The sample app
- Understanding the benefits of a test framework
-
Building the core of a test framework
-
1. Creating an NPM package of my very own
- Creating the project
-
Customizing
package.json - Creating the executable file
- Creating the runner
- Linking the sample application to the library project
- Update the test runner to run our existing script
- Verify that it works by breaking a test
- Catch exceptions from the await call
- Committing to Git
- Summary
-
2. Building
itto define a test- Adding scoped context
- Handling exceptions
- Printing test descriptions
- Support CI with correct exit codes
- Summarizing a test run
- Summary
-
3. Grouping tests with
describe-
A starting point for
describe - Rethinking test output
- Saving test context information
-
Supporting nested
describeblocks - Summary
-
A starting point for
-
4. Promoting conciseness with
beforeEachandafterEach-
Applying
beforeEachblocks to our test - Updating the sample application
-
Defining
afterEach -
Generalizing
beforeEach -
Generalizing
invokeBefores - Summary
-
Applying
-
5. Improving legibility with
expect-
Starting with the
toBeDefinedmatcher -
Creating an
Errorsubtype - Allowing multiple failures per test
- Making a mess
- Summary
-
Starting with the
-
1. Creating an NPM package of my very own
-
Constructing a usable framework
-
6. Formatting expectation errors
-
Building
stackTraceFormatter - Joining up our formatter with the runner
- Summary
-
Building
-
7. Automatically discovering test files
- Discovering files
- Running a single file
- Summary
-
8. Focusing on tests with
it.onlyanddescribe.only-
Parsing
describe -
Adding
it -
Adding
beforeEachandafterEach - Implementing the run phase
- Updating the runner
-
Moving out
expect - Adding the focus functions
- Filtering tests
- Summary
-
Parsing
-
9. Supporting asynchronous tests
-
Waiting for
Promisecompletion - Testing it out
- Catching exceptions
-
Timing out tests after a period of time with
it.timesOutAfter - Testing it out
- Summary
-
Waiting for
-
10. Reporting
- Adding an event dispatcher
- Dispatching a begin suite event
- Dispatching a test finished event
- Summary
-
6. Formatting expectation errors
-
Extending for power users
-
11. Sharing behavior with
it.behavesLike- Implementing a shared example repository
- Summary
-
12. Tagging tests
- Thinking through design options
-
Adding tags on
describe -
Adding tags on
it - Filtering to only tagged tests
- Adding tags to the sample application
- Summary
-
13. Skipping tests
-
Adding the
.skipextensions - Testing it out
-
Supporting no-body
describeandit - Summary
-
Adding the
-
14. Randomizing tests
- Adding the flag
- Summary
-
11. Sharing behavior with
-
Future chapters
- 15. Supporting preprocessors
- 16. Watch mode
-
Where to go from here
-
- Give feedback
- This was a spike
- Ideas for refactoring
- Ideas for extensions
-
Contribute to
concise-test
-
- Notes
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