test(browser): the cross-host fixture uses the object selector form

test/browser/browser_test.go

@@ -281,11 +281,17 @@ func TestBrowserAxFindAgreesAcrossHosts(t *testing.T) {
 	if err := verifierInstance.PushSnapshot(verifier.SnapshotInput{Tree: tree}); err != nil {
 		t.Fatalf("push snapshot: %v", err)
 	}
-	change, ok := verifierInstance.ChangedExtractors()["found"]
-	if !ok {
-		t.Fatal("the goja host recorded no reading for the found extractor")
+	if count := verifierInstance.ExtractorCount(); count != 1 {
+		t.Fatalf("the goja host registered %d extractors, want the fixture's 1", count)
+	}
+	// ChangedExtractors omits an extractor whose reading is null and unchanged,
+	// which is exactly what a selector resolving nothing produces. With the
+	// count checked above, an absent entry is a null reading and not a missing
+	// extractor, so reporting it as null names the real failure.
+	fromGoja := "null"
+	if change, ok := verifierInstance.ChangedExtractors()["found"]; ok {
+		fromGoja = string(change.Curr)
 	}
-	fromGoja := string(change.Curr)
 
 	// Pinned, not just compared: two hosts that both resolved nothing would
 	// agree on undefined and prove nothing about the walk.

test/browser/testdata/find-order/spec.ts

@@ -4,11 +4,11 @@ import { always, extract, taps } from "@sanderling/spec";
 // compared between the two hosts by TestBrowserAxFindAgreesAcrossHosts, which
 // drives each host's production path and never asks one what the other said.
 //
-// Written in the "k:v" string grammar because that is the one form both hosts
-// resolve the same way: the object form {id: "x"} reaches the goja host as a
-// plain attribute filter, and a web hierarchy dump carries the id under
-// resource-id, so it matches nothing there.
-const found = extract((s) => s.ax.find("id:x")?.text).named("found");
+// Written in the object form on purpose. It used to reach the goja host as a
+// plain attribute filter looking for an `id` attribute a dump never carries
+// (the web dump files the DOM id under resource-id), so it resolved nothing
+// there while the V8 host resolved it against the live DOM.
+const found = extract((s) => s.ax.find({ id: "x" })?.text).named("found");
 
 const findsTheShadowMatch = always(() => found.current === "shadow");