Add tests for regexp variables in query strings

Fix how regular expression gets built for query string so that order of parameters is always preserved

mux_test.go

@@ -489,6 +489,24 @@ func TestQueries(t *testing.T) {
 			path:        "",
 			shouldMatch: true,
 		},
+		{
+			title:       "Queries route with regexp pattern, match",
+			route:       new(Route).Queries("foo", "{v1:[0-9]+}"),
+			request:     newRequest("GET", "http://localhost?foo=10"),
+			vars:        map[string]string{"v1": "10"},
+			host:        "",
+			path:        "",
+			shouldMatch: true,
+		},
+		{
+			title:       "Queries route with regexp pattern, regexp does not match",
+			route:       new(Route).Queries("foo", "{v1:[0-9]+}"),
+			request:     newRequest("GET", "http://localhost?foo=a"),
+			vars:        map[string]string{},
+			host:        "",
+			path:        "",
+			shouldMatch: false,
+		},
 	}
 
 	for _, test := range tests {

route.go

@@ -339,15 +339,19 @@ func (r *Route) PathPrefix(tpl string) *Route {
 // - {name:pattern} matches the given regexp pattern.
 
 func (r *Route) Queries(pairs ...string) *Route {
+	length := len(pairs)
+	if length%2 != 0 {
+		r.err = fmt.Errorf(
+			"mux: number of parameters must be multiple of 2, got %v", pairs)
+		return nil
+	}
 	var buf bytes.Buffer
-	var queries map[string]string
-	buf.WriteString("")
-	queries, r.err = mapFromPairs(pairs...)
-	for k, v := range queries {
-		buf.WriteString(fmt.Sprintf("%s=%s&", k, v))
+	for i := 0; i < length; i += 2 {
+		buf.WriteString(fmt.Sprintf("%s=%s&", pairs[i], pairs[i+1]))
 	}
 	tpl := strings.TrimRight(buf.String(), "&")
 	r.err = r.addRegexpMatcher(tpl, false, true, true)
+
 	return r
 }