issue 1840/S2: take a narrowed watch's current values as a set, since the bus hands them in the order of their last revision

go/process/state_integration_test.go

@@ -180,6 +180,18 @@ func TestStateWatchOnAGrantedBucket(t *testing.T) {
 	if len(narrow) != 2 {
 		t.Fatalf("a narrowed watch handed %d current values, want 2", len(narrow))
 	}
+	// the current values come in the order of their last revision, not of their keys: taken as a set.
+	narrowCurrent := map[string]bool{}
+	for len(narrow) > 0 {
+		c := <-narrow
+		if !c.Current || c.Op != "put" {
+			t.Fatalf("a narrowed watch's current value arrived as %+v", c)
+		}
+		narrowCurrent[c.Key] = true
+	}
+	if !narrowCurrent["a.x"] || !narrowCurrent["a.y"] {
+		t.Fatalf("a narrowed watch's current values %v, want a.x and a.y", narrowCurrent)
+	}
 
 	if _, err := s.Put("a.x", 5); err != nil {
 		t.Fatal(err)
@@ -203,8 +215,8 @@ func TestStateWatchOnAGrantedBucket(t *testing.T) {
 	for _, want := range []string{"a.x", "a.y"} {
 		select {
 		case c := <-narrow:
-			if c.Key != want {
-				t.Fatalf("narrowed watch got %+v, want %s", c, want)
+			if c.Key != want || c.Current {
+				t.Fatalf("narrowed watch got %+v, want the change of %s", c, want)
 			}
 		case <-time.After(10 * time.Second):
 			t.Fatalf("narrowed watch missed %s", want)