Read a pull's held asks with Fetch, hand them back all through a build, and drop a duplicate only while its builder's key is fresh (issue 1649)

internal/link/held_asks_test.go

@@ -1,7 +1,6 @@
 package link
 
 import (
-	"errors"
 	"testing"
 	"time"
 
@@ -13,24 +12,24 @@ import (
 
 type fakeHeld struct{ msgs []*nats.Msg }
 
-func (f *fakeHeld) NextMsg(time.Duration) (*nats.Msg, error) {
+func (f *fakeHeld) Held() *nats.Msg {
 	if len(f.msgs) == 0 {
-		return nil, nats.ErrTimeout
+		return nil
 	}
 	m := f.msgs[0]
 	f.msgs = f.msgs[1:]
-	return m, nil
+	return m
 }
 
-type brokenHeld struct{}
+type emptyHeld struct{}
 
-func (brokenHeld) NextMsg(time.Duration) (*nats.Msg, error) { return nil, errors.New("closed") }
+func (emptyHeld) Held() *nats.Msg { return nil }
 
 func TestEveryMessageAPullHoldsIsHandedBackBeforeABuildStarts(t *testing.T) {
 	a := &fakeHeld{msgs: []*nats.Msg{{Subject: "a1"}, {Subject: "a2"}}}
 	b := &fakeHeld{msgs: []*nats.Msg{{Subject: "b1"}}}
 	var back []string
-	n := handBackHeld([]heldSource{a, brokenHeld{}, b}, func(m *nats.Msg) { back = append(back, m.Subject) })
+	n := handBackHeld([]heldSource{a, emptyHeld{}, b}, func(m *nats.Msg) { back = append(back, m.Subject) })
 	if n != 3 || len(back) != 3 || back[0] != "a1" || back[2] != "b1" {
 		t.Fatalf("handed back %d %v; want a1 a2 b1", n, back)
 	}