implement tests for selection methods with invalid selector strings

expand_test.go

@@ -9,6 +9,16 @@ func TestAdd(t *testing.T) {
 	assertLength(t, sel.Nodes, 19)
 }
 
+func TestAddInvalid(t *testing.T) {
+	sel1 := Doc().Find("div.row-fluid")
+	sel2 := sel1.Add("")
+	assertLength(t, sel1.Nodes, 19)
+	assertLength(t, sel2.Nodes, 19)
+	if sel1 == sel2 {
+		t.Errorf("selections should not be the same")
+	}
+}
+
 func TestAddRollback(t *testing.T) {
 	sel := Doc().Find(".pvk-content")
 	sel2 := sel.Add("a").End()