Fixes panic on printing user parts when non exist

format_test.go

@@ -2,67 +2,58 @@ package main
 
 import (
 	"net/url"
-	"runtime/debug"
 	"strconv"
 	"testing"
 )
 
 func TestFormat(t *testing.T) {
 	cases := []struct {
-		url       string
-		format    string
-		expected  string
-		wantPanic bool
+		url      string
+		format   string
+		expected string
 	}{
-		{"https://example.com/foo", "%d", "example.com", false},
-		{"https://example.com/foo", "%d%p", "example.com/foo", false},
-		{"https://example.com/foo", "%s://%d%p", "https://example.com/foo", false},
+		{"https://example.com/foo", "%d", "example.com"},
+		{"https://example.com/foo", "%d%p", "example.com/foo"},
+		{"https://example.com/foo", "%s://%d%p", "https://example.com/foo"},
 
-		{"https://example.com:8080/foo", "%d", "example.com", false},
-		{"https://example.com:8080/foo", "%P", "8080", false},
+		{"https://example.com:8080/foo", "%d", "example.com"},
+		{"https://example.com:8080/foo", "%P", "8080"},
 
-		{"https://example.com/foo?a=b&c=d", "%p", "/foo", false},
-		{"https://example.com/foo?a=b&c=d", "%q", "a=b&c=d", false},
+		{"https://example.com/foo?a=b&c=d", "%p", "/foo"},
+		{"https://example.com/foo?a=b&c=d", "%q", "a=b&c=d"},
 
-		{"https://example.com/foo#bar", "%f", "bar", false},
-		{"https://example.com#bar", "%f", "bar", false},
+		{"https://example.com/foo#bar", "%f", "bar"},
+		{"https://example.com#bar", "%f", "bar"},
 
-		{"https://example.com#bar", "foo%%bar", "foo%bar", false},
-		{"https://example.com#bar", "%s://%%", "https://%", false},
+		{"https://example.com#bar", "foo%%bar", "foo%bar"},
+		{"https://example.com#bar", "%s://%%", "https://%"},
 
-		{"https://example.com:8080/?foo=bar#frag", "%:", ":", false},
-		{"https://example.com/", "%:", "", false},
+		{"https://example.com:8080/?foo=bar#frag", "%:", ":"},
+		{"https://example.com/", "%:", ""},
 
-		{"https://example.com:8080/?foo=bar#frag", "%?", "?", false},
-		{"https://example.com/", "%?", "", false},
+		{"https://example.com:8080/?foo=bar#frag", "%?", "?"},
+		{"https://example.com/", "%?", ""},
 
-		{"https://example.com:8080/?foo=bar#frag", "%#", "#", false},
-		{"https://example.com/", "%#", "", false},
+		{"https://example.com:8080/?foo=bar#frag", "%#", "#"},
+		{"https://example.com/", "%#", ""},
 
-		{"https://user:[email protected]:8080/?foo=bar#frag", "%u", "user:pass", false},
-		{"https://user:[email protected]:8080/?foo=bar#frag", "%@", "@", false},
-		{"https://example.com/", "%@", "", false},
-		{"https://example.com/", "%u", "", true},
+		{"https://user:[email protected]:8080/?foo=bar#frag", "%u", "user:pass"},
+		{"https://user:[email protected]:8080/?foo=bar#frag", "%@", "@"},
+		{"https://example.com/", "%@", ""},
+		{"https://example.com/", "%u", ""},
 
-		{"https://user:[email protected]:8080/?foo=bar#frag", "%a", "user:[email protected]:8080", false},
-		{"https://example.com:8080/?foo=bar#frag", "%a", "example.com:8080", true},
-		{"https://example.com/?foo=bar#frag", "%a", "example.com", true},
+		{"https://user:[email protected]:8080/?foo=bar#frag", "%a", "user:[email protected]:8080"},
+		{"https://example.com:8080/?foo=bar#frag", "%a", "example.com:8080"},
+		{"https://example.com/?foo=bar#frag", "%a", "example.com"},
 
-		{"https://sub.example.com:8080/foo", "%S", "sub", false},
-		{"https://sub.example.com:8080/foo", "%r", "example", false},
-		{"https://sub.example.com:8080/foo", "%t", "com", false},
+		{"https://sub.example.com:8080/foo", "%S", "sub"},
+		{"https://sub.example.com:8080/foo", "%r", "example"},
+		{"https://sub.example.com:8080/foo", "%t", "com"},
 	}
 
 	for i, c := range cases {
 
 		t.Run(strconv.Itoa(i), func(t *testing.T) {
-			defer func() {
-				r := recover()
-				if (r != nil) != c.wantPanic {
-					t.Errorf("panic recover = %v, wantPanic = %v", r, c.wantPanic)
-					debug.PrintStack()
-				}
-			}()
 
 			u, err := url.Parse(c.url)
 			if err != nil {

main.go

@@ -164,7 +164,9 @@ func format(u *url.URL, f string) []string {
 
 		// the userinfo; e.g. user:pass
 		case 'u':
-			out.WriteString(u.User.String())
+			if u.User != nil {
+				out.WriteString(u.User.String())
+			}
 
 		// the domain; e.g. sub.example.com
 		case 'd':