08_Chapter_8_Boundaries.md

Chapter 8: Boundaries [Slide]

We seldom control all the software in our systems. Sometimes we buy third-party packages or use open source. Other times we depend on teams in our own company to produce components or subsystems for us.

Using Third-Party Code

• Interface providers strive for broad applicability, while interface users want it to be focused on their needs
• Don’t pass map outside of system (eg. Public API) boundaries

Exploring and learning boundaries

Learning test: We call third-party API, as we expect to use it in our application

Learning log4j

We write test to see how it works

Learning tests are better than free

Learning tests helps us to find boundary tests and ease our migrations if there is any breaking change in new releases

Clean boundaries

Change is inevitable in software

Code at the boundaries needs clear separation and tests that define expectations