bob 🔨

Generate fixtures easily.

Inspired by classical factory_bot-like fixtures replacement libraries, bob uses simple functions as the primary mechanism to override default values instead of relying on annotations or a builder-pattern API.

bob requires go 1.18+.

Installation

go get github.com/mech-pig/bob

Usage

Create a builder

A builder is created by providing a function that is used to generate a default instance.

type User struct {
    Name string
    Age int
}

userBuilder := bob.New(func () User {
    return User{
        Name: "test",
        Age: 18,
    }
})

Build an instance

Instances are created with the Build method.

userBuilder.Build()

The build method accepts an optional list of functions that are used to customize the instance. An override function takes an instance as input and returns a modified one.

func nameIsBob(u User) User {
    u.Name = "bob"
    return u
}

func ageIs15(u User) User {
    u.Age = 15
    return u
}

userBuilder.Build(nameIsBob, is15)

Derive builder from an existing one

The Override method can be used to derive a new builder from an existing one:

bobUserBuilder := userBuilder.Override(nameIsBob)
bobUserBuilder.Build()

Build many instances

The BuildMany method is used to build multiple instances at once. It accepts an int to indicate the number of instances that will be generated.

userBuilder.BuildMany(5)

Like Build, it's possible to customise the generated instances by providing one or more overriding functions. Each of these function takes as input an index and the default instance

userBuilder.BuildMany(3, func (i int, u User) User {
    u.Name = fmt.Sprint("user-", i)
    return u
})