[short] skip
[gccgo] skip # gccgo has no cover tool

go test -short -cover -covermode=atomic -coverpkg=coverdep/p1 coverdep

-- coverdep/p.go --
package p

import _ "coverdep/p1"

func F() {
}
-- coverdep/p1/p1.go --
package p1

import _ "errors"
-- coverdep/p_test.go --
package p

import "testing"

func Test(t *testing.T) {
	F()
}