Chapter 4: Seam Model

Place where you can alter behaviour in your program without editing in that place.

Main usage: to cut dependency

Type of Seams

• Preprocessing Seams: example C++ macro
• Link Seams: example python mock
• Object Seams: implement interface, then change the object

Chapter 6: I Don’t Have Much Time and I Have to Change It

Sprout method

• Create a separate function and just call that function from the main method
• At least that function can be tested

Sprout class

• Similar with sprout method (but create a new class), when you need to modify a class, but the class not easily instantiated (because of a lots of dependency)
• Cons: gut the abstractions, since the main purpose is just to put something under test

Wrap method

• Either:
  • Rename the old method and wrap it with a new method with the same name with the old one, and create a new method (that can be tested) and call it before/after the old renamed method is called, or
  • Create a new method that call the old method, the new method can be added things (e.g. new method that can be tested) on after/before the old method is called