fix(hierarchy): reach a web test tag through testTag and testID

Compose for Web writes a test tag as data-testid, which is what the web
runtime resolves both names against. testTag aliased onto the three
identifier keys and not that one, and testID aliased onto nothing at
all, so a tag the web runtime found on every row of a list named no
element here and every property over it passed vacuously.

internal/hierarchy/hierarchy.go

@@ -274,8 +274,11 @@ var attributeAliases = map[string][]string{
 	// iOS identifier names
 	"identifier":              {"resource-id", "accessibilityIdentifier"},
 	"accessibilityIdentifier": {"resource-id", "identifier"},
-	// Compose testTag surfaces as resource-id on Android, accessibilityIdentifier on iOS
+	// Compose testTag surfaces as resource-id on Android, accessibilityIdentifier
-	"testTag": {"resource-id", "identifier", "accessibilityIdentifier"},
+	// on iOS and data-testid on web, which is the key the web runtime resolves
+	// both names against.
+	"testTag": {"resource-id", "identifier", "accessibilityIdentifier", "data-testid"},
+	"testID":  {"data-testid"},
 	// iOS AXElement raw name for hintText
 	"placeholderValue": {"hintText"},
 	// iOS AXElement raw name for class

internal/hierarchy/hierarchy_test.go

@@ -653,6 +653,43 @@ func TestAccessibilityLabelAliasesStillReachAccessibilityText(t *testing.T) {
 	}
 }
 
+// Compose for Web writes a test tag as data-testid, the key the web runtime
+// resolves testTag and testID against. testTag reached the three identifier
+// keys and not that one, and testID aliased onto nothing at all, so a tag the
+// web runtime found on both rows named no element here.
+func TestTestTagAliasesReachDataTestID(t *testing.T) {
+	tree, _ := Parse(webAttrDump)
+	for _, key := range []string{"testTag", "testID"} {
+		element := tree.Find(key + ":customer-row")
+		if element == nil {
+			t.Fatalf("expected %s: to match the data-testid attribute via alias", key)
+		}
+		if element.ResourceID != "customer_row_a1" {
+			t.Fatalf("%s: matched %q, want customer_row_a1", key, element.ResourceID)
+		}
+		object := tree.FindBySelector(Selector{Filters: []AttrFilter{
+			{Attr: key, Value: "customer-row"},
+		}})
+		if object == nil {
+			t.Fatalf("expected the object form of %s to match data-testid via alias", key)
+		}
+		if object.ResourceID != element.ResourceID {
+			t.Fatalf("the object form of %s matched %q, want %q",
+				key, object.ResourceID, element.ResourceID)
+		}
+	}
+}
+
+// testTag keeps reaching the identifier keys android and ios write it under.
+func TestTestTagStillReachesTheIdentifierKeys(t *testing.T) {
+	if tree, _ := Parse(androidAttrDump); tree.Find("testTag:row1") == nil {
+		t.Fatal("expected testTag: to match the resource-id attribute via alias")
+	}
+	if tree, _ := Parse(iosAttrDump); tree.Find("testTag:Feed") == nil {
+		t.Fatal("expected testTag: to match the identifier attribute via alias")
+	}
+}
+
 func TestContentDescAliasOnIOS(t *testing.T) {
 	tree, _ := Parse(iosAttrDump)
 	el := tree.Find("content-desc:Close")