In this module, you’ll learn how to create high-level Nullable infrastructure wrappers that make application code easier to write and test. You’ll build Rot13Client, an infrastructure wrapper for a ROT-13 microservice.

Concepts

Download the slides and transcript here.

Direct links to patterns discussed in this module:

• Infrastructure Wrappers
• Fake It Once You Make It
• Paranoic Telemetry
• Nullables
• Configurable Responses
• Output Tracking

Primers

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

• JavaScript Basics
• Introduced in challenge #1:
  • await
  • Object Shorthand
• Introduced in challenge #2:
  • async
  • Object Destructuring
• Introduced in challenge #3:
  • Default Function Parameters
• Introduced in challenge #5:
  • Nullish Coalescing Operator (??)
  • Computed Property Names
• Introduced in challenge #6:
  • Renaming Destructured Variables
  • Arrow Functions
• Introduced in challenge #8:
  • String Interpolation
• Introduced in challenge #10:
  • Private Methods (#)
• Introduced in challenge #11:
  • Using Promises

Exercise Setup

Start with the Pre-Course Setup. Then:

1. Check out the code

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

2. Prepare to start working

1. Open the exercise files:
   • src/www/infrastructure/_rot13_client_test.js (or .ts)
   • src/www/infrastructure/rot13_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 #5, you’ll have covered the most important information.

1. Challenge #1: Fake It Once You Make It
2. Challenge #2: Signature Shielding
3. Challenge #3: Parsing Responses
4. Challenge #4: Request Tracking
5. Challenge #5: Nullability
6. Challenge #6: Configurable Responses
7. Challenge #7: Unexpected Status
8. Challenge #8: Simulating Errors
9. Challenge #9: Refactoring
10. Challenge #10: Edge Cases
11. Challenge #11: Design Changes
12. Bonus Challenges

Start with Challenge #1

Return to course overview