Injecting Dependencies for Fun and Profit

on YouTube ↗29m

" summary

Concrete examples show constructor-based injection replacing globals, with tests using RSpec verifying doubles via instance_double and allow/expect; failure behavior is exercised by having the weather service raise a NoPredictionAvailable error and asserting the fallback speech or mailer output. The talk contrasts this with partial mocking/monkeypatching, explains why explicit dependency lists aid comprehension and testing, and shows Rails-friendly service objects and mailer wiring — the presenter mentions using it across about 40 Rails apps.

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" chapters (9)

1. 0:00Start
2. 0:33Dependency Injection's Benefits
3. 0:55Intro to Dependency Injection
4. 13:51Wait, Why Didn’t We Partially Mock?
5. 18:06How Do I Inject Dependencies in Rails?
6. 22:02Takeaways
7. 22:40Sad Paths are Part of Your UX
8. 22:55Explicit Dependencies Help You Know Your Code
9. 23:19Dependency Injection is Possible & Useful in Rails

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