The adapter pattern in Go

In software development, testability problems are often caused by underlying design problems. If code is not testable, it is not well-designed.

External dependencies like databases can present both design and testing problems, which can be solved by using the adapter pattern to encapsulate all knowledge about the specific dependency in a single component.

Adapters act as ambassadors, representing the program to the external system and translating messages to and from it. This decouples knowledge of the external system from the rest of the program and solves the testability problem by allowing the program to be tested without the external dependency.

The PostgresStore adapter pattern is an example of this design pattern being used to solve the problem of testing code that relies on a database. By breaking the dependency between the business logic and the storage logic, the program becomes easier to test and easier to understand.