-- aa/aa.go --
package aa

import "M/it"

func AA(y int) int {
	c := it.Conc{}
	x := it.Callee(&c)
	println(x, y)
	return 0
}
-- aa/aa_test.go --
package aa

import "testing"

func TestMumble(t *testing.T) {
	AA(3)
}
-- b/b.go --
package b

func init() {
	println("package 'b' init: release the kraken")
}

func BFunc() int {
	return -42
}
-- b/b_test.go --
package b

	if x < 0 {
		return -x
	}
	return 42
}

func Grumble(y int) int {
	return -y
}

func main() {
}

-- prog_test.go --
package main

import (
	"testing"
)

func TestMumble(t *testing.T) {
	if x := Mumble(10); x != 42 {
		t.Errorf("Mumble(%d): got %d want %d", 10, x, 42)
	}