On Mocking Functionality in Go Tests 

The back-bone of Go is composed of Interfaces and Structures. Interfaces allow for grouping supported functionality into logical groups, much like Classes in other languages. Defining what a logical group might do is the job of an Interface. Whereas Structures house the actual implementation of the functionality. Structures describe what a logical group actually does, within the context of its Interface. The caveat is, Go does not support explicitly defining relationships between Interfaces and Structures.

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