Using test helpers in Go -- how do I know which test failed with vim-go?

foobar.go

package main

func AddTwo(input int) int {
	return input + 2
}

func AddFour(input int) int {
	return input + 4
}

foobar_test.go

package main

import "testing"

func TestAddTwo(t *testing.T) {
	if !testIntegers(t, 2, AddTwo(1)) {
		return
	}
}
func TestAddFour(t *testing.T) {
	if !testIntegers(t, 2, AddFour(1)) {
		return
	}
}

func testIntegers(t *testing.T, expected, actual int) bool {
	if expected != actual {
		t.Errorf("wrong integer. want=%d, got=%d",
			expected, actual)
		return false
	}
	return true
}