Golang代码循环依赖问题

package A
import (
 "strings"
 B “/GoProject/main/gobase/cycle/b"
)
func Foo(a string) (string) {
 return B.Add(a)
}
func Minus(a string) (string) {
 return strings.Trim(a, "\t")
}

package B
import A "GoProject/main/gobase/cycle/a"
func Goo(a string) (string) {
 return A.Minus(a)
}
func Add(a string) (string) {
 return a + "----"
}

package cycle
import (
 "testing"
 A "GoProject/main/gobase/cycle/a"
)
func TestCycle(t *testing.T) {
 A.Foo("good")
}

packageGoProject/main/gobase/cycle (test)
 imports /GoProject/main/gobase/cycle/a
 importsGoProject/main/gobase/cycle/b
 imports GoProject/main/gobase/cycle/a: import cycle not allowed
FAIL

package service
type A interface {
 Minus(s string) (string)
}
type B interface {
 Add(s string) (string)
}

package A
import (
 "strings"
 "github.com/hundred666/GoTest/service"
)
type AImpl struct {
 b service.B
}
func (a *AImpl) Foo(s string) (string) {
 return a.b.Add(s)
}
func (a *AImpl) Minus(s string) (string) {
 return strings.Trim(s, "\t")
}

package B
import "github.com/hundred666/GoTest/service"
type BImpl struct {
 a service.A
}
func (b *BImpl) Goo(a string) (string) {
 return b.a.Minus(a)
}
func (b *BImpl) Add(a string) (string) {
 return a + "----"
}

func NewA() *AImpl {
 return new(AImpl)
}
func (a *AImpl) SetB(b service.B) {
 a.b = b
}

func NewB() *BImpl {
 return new(BImpl)
}
func (b *BImpl) SetA(a service.A) {
 b.a = a
}

package main
import (
 "github.com/hundred666/GoTest/B"
 "github.com/hundred666/GoTest/A"
 "fmt"
)
func main() {
 b := B.NewB()
 a := A.NewA()
 a.SetB(b)
 r := a.Foo("aa")
 fmt.Println(r)
 }