fix: modify interface check way on selector (#2399)

selector/default_node.go

@@ -6,6 +6,8 @@ import (
 	"github.com/go-kratos/kratos/v2/registry"
 )
 
+var _ Node = (*DefaultNode)(nil)
+
 // DefaultNode is selector node
 type DefaultNode struct {
 	scheme   string

selector/default_selector.go

@@ -5,6 +5,11 @@ import (
 	"sync/atomic"
 )
 
+var (
+	_ Rebalancer = (*Default)(nil)
+	_ Builder    = (*DefaultBuilder)(nil)
+)
+
 // Default is composite selector.
 type Default struct {
 	NodeBuilder WeightedNodeBuilder

selector/node/direct/direct.go

@@ -13,8 +13,8 @@ const (
 )
 
 var (
-	_ selector.WeightedNode        = &Node{}
+	_ selector.WeightedNode        = (*Node)(nil)
-	_ selector.WeightedNodeBuilder = &Builder{}
+	_ selector.WeightedNodeBuilder = (*Builder)(nil)
 )
 
 // Node is endpoint instance

selector/node/ewma/node.go

@@ -21,8 +21,8 @@ const (
 )
 
 var (
-	_ selector.WeightedNode        = &Node{}
+	_ selector.WeightedNode        = (*Node)(nil)
-	_ selector.WeightedNodeBuilder = &Builder{}
+	_ selector.WeightedNodeBuilder = (*Builder)(nil)
 )
 
 // Node is endpoint instance