tracing url parsing

url_test.go

@@ -57,13 +57,17 @@ func printURLTree(t *testing.T, a Node) {
 	notation.Lprintw(t, a)
 }
 
-func urlParser() func(string) (Node, error) {
+func urlParser(trace bool) func(string) (Node, error) {
 	b, err := os.ReadFile("doc/example/url.treerack")
 	if err != nil {
 		panic(err)
 	}
 
 	p := new(Syntax)
+	if trace {
+		p.MaxTraceLength = 180
+	}
+
 	if err = p.ReadSyntax(bytes.NewBuffer(b)); err != nil {
 		panic(err)
 	}
@@ -1524,12 +1528,13 @@ func TestURL(t *testing.T) {
 				}
 
 				var d time.Duration
-				p := urlParser()
+				p := urlParser(test.bench <= 0)
 				for i := 0; i < n && !t.Failed(); i++ {
 					start := time.Now()
 					a, err := p(test.input)
 					d += time.Since(start)
 					if err != nil {
+						Trace(t.Output(), err)
 						t.Fatal(err)
 					}
 
@@ -1581,7 +1586,7 @@ func TestURLErrors(t *testing.T) {
 		input: "http://foo.bar/foo%xbar",
 	}} {
 		t.Run(test.title, func(t *testing.T) {
-			p := urlParser()
+			p := urlParser(false)
 			if a, err := p(test.input); err == nil {
 				printURLTree(t, a)
 				t.Fatal("failed to fail", test.input)