fix(route): redirectSlash bug (gin-gonic#3227)

fixes gin-gonic#2959
fixes gin-gonic#2282
fixes gin-gonic#2211

tree.go

@@ -107,7 +107,8 @@ func countSections(path string) uint16 {
 type nodeType uint8
 
 const (
-	root nodeType = iota + 1
+	static nodeType = iota
+	root
 	param
 	catchAll
 )
@@ -173,6 +174,7 @@ walk:
 			child := node{
 				path:      n.path[i:],
 				wildChild: n.wildChild,
+				nType:     static,
 				indices:   n.indices,
 				children:  n.children,
 				handlers:  n.handlers,
@@ -604,6 +606,11 @@ walk: // Outer loop for walking the tree
 				return
 			}
 
+			if path == "/" && n.nType == static {
+				value.tsr = true
+				return
+			}
+
 			// No handle found. Check if a handle for this path + a
 			// trailing slash exists for trailing slash recommendation
 			for i, c := range []byte(n.indices) {

tree_test.go

@@ -684,6 +684,26 @@ func TestTreeRootTrailingSlashRedirect(t *testing.T) {
 	}
 }
 
+func TestRedirectTrailingSlash(t *testing.T) {
+	var data = []struct {
+		path string
+	}{
+		{"/hello/:name"},
+		{"/hello/:name/123"},
+		{"/hello/:name/234"},
+	}
+
+	node := &node{}
+	for _, item := range data {
+		node.addRoute(item.path, fakeHandler("test"))
+	}
+
+	value := node.getValue("/hello/abx/", nil, getSkippedNodes(), false)
+	if value.tsr != true {
+		t.Fatalf("want true, is false")
+	}
+}
+
 func TestTreeFindCaseInsensitivePath(t *testing.T) {
 	tree := &node{}