go get github.com/vburenin/ifacemaker

$ ifacemaker --help
Usage:
  ifacemaker [OPTIONS]

Application Options:
  -f, --file=          Go source file to read
  -s, --struct=        Generate an interface for this structure name
  -i, --iface=         Name of the generated interface
  -p, --pkg=           Package name for the generated interface
  -y, --iface-comment= Comment for the interface, default is '// <iface> ...'
  -d, --doc=           Copy docs from methods (default: true)
  -D, --type-doc       Copy type doc from struct
  -c, --comment=       Append comment to top
  -o, --output=        Output file name. If not provided, result will be printed to stdout.

Help Options:
  -h, --help           Show this help message
$

package main

import "fmt"

type Human struct {
	name string
	age  int
}

// Returns the name of our Human.
func (h *Human) GetName() string {
	return h.name
}

// Our Human just had a birthday! Increase its age.
func (h *Human) Birthday() {
	h.age += 1
	fmt.Printf("I am now %d years old!\n", h.age)
}

// Make the Human say hello.
func (h *Human) SayHello() {
	fmt.Printf("Hello, my name is %s, and I am %d years old.\n", h.name, h.age)
}

func main() {
	human := &Human{name: "Bob", age: 30}
	human.GetName()
	human.SayHello()
	human.Birthday()
}

$ ifacemaker -f human.go -s Human -i HumanIface -p humantest -y "HumanIface makes human interaction easy" -c "DONT EDIT: Auto generated"
// DONT EDIT: Auto generated

package humantest

// HumanIface makes human interaction easy
type HumanIface interface {
	// Returns the name of our Human.
	GetName() string
	// Our Human just had a birthday! Increase its age.
	Birthday()
	// Make the Human say hello.
	SayHello()
}

$

$ ifacemaker -f human.go -s Human -i HumanIface -p humantest -y "HumanIface makes human interaction easy" -c "DONT EDIT: Auto generated" -o humaniface.go
$