jrlangford / gospec

gospec

An implementation of the specification pattern in Go.

The module includes a regular implementation and a traceable one, which can 'explain' its execution.

Quick Start

Embed BaseSpecification, instantiated to the type that will be tested, in your own specification. Ensure the method that checks for specification satisfaction has the following signature: IsSatisfiedBy(t T) bool.

type User struct {
  id      string
  name    string
}

type IsBob struct {
  BaseSpecification[User]
}

func NewIsBob() *IsBob {
  s := IsBob{}
  s.Init(&s)
  return &s
}

func (s *IsBob) IsSatisfiedBy(u User) bool {
  return u.name == "Bob"
}

Once you have defined and instantiated several specifications you can compose a more complex one by using Boolean operators.

adultSpec := NewIsLegalAdult()
flaggedSpec := NewIsFlagged()
bobSpec := NewIsBob()

compositeSpec := adultSpec.Not().Or(flaggedSpec).Or(bobSpec),

satisfied := compositeSpec.IsSatisfiedBy(userBob)

Use BaseTSpecification instead if you want to be able to trace the execution of Boolean operations in a composite specification. This type requires the addition of a GetName() string method to your specification and also the inclusion of a 'Tracer', an interface that can process operation trace instances (OpTrace).

type IsFlagged struct {
  gospec.BaseTSpecification[User]
  flaggedIDs  []string
  specName    string
}

func NewIsFlagged(t gospec.Tracer) *IsFlagged {
  s := IsFlagged{
    flaggedIDs: []string{"1"},
    specName:   "IsFlaggedSpec",
  }
  s.Init(&s, t)
  return &s
}

func (s *IsFlagged) IsSatisfiedBy(u User) bool {
  for _, id := range s.flaggedIDs {
    if id == u.id {
      return true
    }
  }
return false
}

func (s *IsFlagged) GetName() string {
  return s.specName
}

Operation trace instances can produce a verbose explanation of their contents.

Run the logged_specification example for a basic demonstration of its functionality.

go test -v examples/logged_specification_test.go

Development Status: Beta

Core features have been tested, trace features have not been tested.