In this module, you’ll learn how to use embedded stubs to make low-level infrastructure Nullable. You’ll add an embedded stub to HttpClient, an infrastructure wrapper for HTTP-based services.

Concepts

Download the slides and transcript here.

Direct links to patterns discussed in this module:

• Embedded Stub
• Thin Wrapper

Primers

You may wish to familiarize yourself with these primers before starting on the exercises:

• JavaScript Basics
• JavaScript Concurrency
• Introduced in challenge #1:
  • await
  • Private Methods (#)
  • Object Shorthand
• Introduced in challenge #2:
  • Arrow Functions
  • Using Promises
  • Creating Promises
  • Using Events
  • Creating Event Emitters
• Introduced in challenge #3:
  • Object Destructuring
• Introduced in challenge #4:
  • Default Function Parameters
• Introduced in challenge #5:
  • Renaming Destructured Variables

Exercise Setup

Start with the Overall Setup. Then:

1. Check out the code

1. Check out the exercise branch:
   • JavaScript: git checkout embedded-stubs-js
   • TypeScript: git checkout embedded-stubs-ts
2. Create a custom branch for your changes:
   • git checkout -b my-embedded-stubs

2. Prepare to start working

1. Open the exercise files:
   • src/node_modules/http/_http_client_test.js (or .ts)
   • src/node_modules/http/http_client.js (or .ts)
2. Run the build watcher from the root of the repository:
   • Windows: .\watch.cmd quick
   • Mac/Linux: ./watch.sh quick
3. Confirm that the build runs and ends with BUILD OK.

Exercises

The course is designed to have more exercises than you can finish in a single session, so don’t worry about finishing everything. Instead, work at your own pace and focus on understanding the material. If you get to the end of challenge #4, you’ll have covered the most important information.

1. Challenge #1: Injecting the Stub
2. Challenge #2: Stubbing Behavior
3. Challenge #3: Default Response
4. Challenge #4: Configurable Responses
5. Challenge #5: Configurable Endpoints
6. Challenge #6: Normalization
7. Challenge #7: Partial Configuration
8. Challenge #8: Infinite Responses
9. Challenge #9: Distinct Responses
10. Challenge #10: Exceptional Responses
11. Challenge #11: Output Tracking
12. Bonus Challenges

Start with Challenge #1

Return to course overview