Test the untestable
Introduction to seams
Legacy code
Is difficult to
- Read
- Understand
- Extend
- Maintain
- Test
Reading primer
To me legacy code is simply code without tests .
Code without tests is bad code. It doesn't matter how well written it is; ... With tests, we can change the behavior of our code quickly and verifiably. Without them we really don't know if our code is getting better or worse.
General set-up
Without tests
DO NOT
change the surface of a class
Create a test suite for it
How without changing the surface?
Taming the beast
unusual test organization
- side by side
- inner classes
Demo
Taming the beast
static is evil
- implicit dependency
- difficult to test
delegate to the rescue
Demo
Taming the beast
delegate is out
- very time consuming
- calls have to change
interface seam
A seam is a place where you can alter behavior in your program without editing in that place .
Michael C. Feather