Go-Circular Import Resolution with Interface for Testing.go

// testhelpers/helpers.go
package testhelpers

// MyFunctionInterface describes the interface for the MyFunction from mypackage.
// This allows avoiding a direct import of mypackage, thus preventing circular imports.
type MyFunctionInterface interface {
    Invoke() string // Assuming MyFunction returns a string
}

// DoSomething uses the interface instead of a specific function from mypackage.
// This function can now work with any implementation of MyFunctionInterface.
func DoSomething(f MyFunctionInterface) string {
    return f.Invoke()
}

// mypackage/myfunction_test.go
package mypackage_test

import (
    "mypackage"
    "path/to/testhelpers"
    "testing"
)

// myFunctionWrapper wraps mypackage.MyFunction to conform to the MyFunctionInterface.
// This allows passing MyFunction to testhelpers.DoSomething without direct dependency.
type myFunctionWrapper struct{}

// Invoke calls the original MyFunction from mypackage, adapting it to the interface.
func (mfw myFunctionWrapper) Invoke() string {
    return mypackage.MyFunction() // Assume MyFunction returns a string
}

// TestMyFunction tests MyFunction using the testhelpers package indirectly via interface.
func TestMyFunction(t *testing.T) {
    wrapper := myFunctionWrapper{}
    result := testhelpers.DoSomething(wrapper)
    expected := "expected result"
    if result != expected {
        t.Errorf("Expected %s, got %s", expected, result)
    }
}