Writing Go tests

A Go test file is simply a set of functions with the following signature:

func Test<Name>(*testing.T)

Here, <Name> is an arbitrary name that reflects the purpose of the test. The test functions are intended to exercise a specific functional unit (or unit test) of the source code.

Before we write the test functions, let us review the code that will be tested. The following source snippet shows a simple implementation of a mathematical vector with Add, Sub, and Scale methods (see the full source code listed at https://github.com/vladimirvivien/learning-go/ch12/vector/vec.go). Notice that each method implements a specific behavior as a unit of functionality, which will make it easy to test:

type Vector interface { 
    Add(other Vector) Vector 
    Sub(other Vector) Vector 
    Scale(factor float64) 
    ... 
} 
 
func New(elems ...float64) SimpleVector { 
    return SimpleVector(elems) 
} 
 
type SimpleVector []float64 
 
func (v SimpleVector) Add(other Vector) Vector...