structsnapshot

structsnapshot

structsnapshot is a Go package that allows you to take a snapshot of a struct, saving its fields, types, and tags in a JSON format. It provides functions to create a snapshot, convert it to JSON, save it to a file, and load a snapshot from a file.

Installing

go install github.com/gustavosbarreto/structsnapshot/cmd/structsnapshot@latest

Using

There are two methods of generating struct snapshots (see bellow).

Regardless of the method you choose, a special directory called __structsnapshots__ will be created in the current working directory. This directory will contain the generated struct snapshots as JSON files for each struct you have configured.

Go generate (RECOMMENDED)

Add a go:generate comment before the struct:

//go:generate structsnapshot User
type User struct {
	Username string `json:"username" validate:"required"`
	Email    string `json:"email" validate:"required,email"`
	Timezone string `json:"timezone" validate:"timezone"`
}

Run go generate:

$ go generate

Standalone

Run the following command on the directory where the User struct is defined:

$ structsnapshot User

Unit testing

After generating struct snapshots, you need to ensure that your structs match the generated snapshots. To accomplish this, you can use the TakeSnapshot(struct) function to generate an in-memory snapshot of the struct. This snapshot can then be compared with the generated snapshot on the filesystem by calling LoadSnapshot(struct) function.

See example.