Developer Testing

Quality

Internal Quality: Code that is loosely coupled, highly cohesive, and is adaptable to change.
External Quality: Code that does what it is supposed to do.

Feedback loops allow use to see what is going on with our code asap.
Developers should intentionally create feedback loops in our code to ensure that our code is doing the right thing.
Inner Loop: Near instananeous checks that happen in our dev environments.
Outer Loops: Checks that happen slower on the repo level such as in the build pipeline

Static
- This is an inner loop test.
- Includes code level protections such as strict types, using an editor config, using a linter, etc.
Unit
- Testing functionality of code in isolation from other code.
- This is an inn loop test.
Integration
- This is when we are testing two or more functional units together
- We want to see how our code integrates with the rest of the code base
- Usually includes testing against other systems such as a database or network
E2E
- Often in the form of a smoke test
- Before we deploy to prod, we wanto to have some automated or manual test to make sure everything is perfect
- This is an expensive test, so we want to depend on the other 3 tests as much as possible