diff --git a/rpcx/internal/chainclientinterceptors_test.go b/rpcx/internal/chainclientinterceptors_test.go
new file mode 100644
index 00000000..7ca6019e
--- /dev/null
+++ b/rpcx/internal/chainclientinterceptors_test.go
@@ -0,0 +1,47 @@
+package internal
+
+import (
+	"context"
+	"sync/atomic"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"google.golang.org/grpc"
+)
+
+func TestWithStreamClientInterceptors(t *testing.T) {
+	opts := WithStreamClientInterceptors()
+	assert.NotNil(t, opts)
+}
+
+func TestWithUnaryClientInterceptors(t *testing.T) {
+	opts := WithUnaryClientInterceptors()
+	assert.NotNil(t, opts)
+}
+
+func TestChainStreamClientInterceptors_zero(t *testing.T) {
+	interceptors := chainStreamClientInterceptors()
+	_, err := interceptors(context.Background(), nil, new(grpc.ClientConn), "/foo",
+		func(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string,
+			opts ...grpc.CallOption) (grpc.ClientStream, error) {
+			return nil, nil
+		})
+	assert.Nil(t, err)
+}
+
+func TestChainStreamClientInterceptors_one(t *testing.T) {
+	var called int32
+	interceptors := chainStreamClientInterceptors(func(ctx context.Context, desc *grpc.StreamDesc,
+		cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (
+		grpc.ClientStream, error) {
+		atomic.AddInt32(&called, 1)
+		return nil, nil
+	})
+	_, err := interceptors(context.Background(), nil, new(grpc.ClientConn), "/foo",
+		func(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string,
+			opts ...grpc.CallOption) (grpc.ClientStream, error) {
+			return nil, nil
+		})
+	assert.Nil(t, err)
+	assert.Equal(t, int32(1), atomic.LoadInt32(&called))
+}
diff --git a/rpcx/internal/target.go b/rpcx/internal/target.go
index 52c7b2a7..3415646e 100644
--- a/rpcx/internal/target.go
+++ b/rpcx/internal/target.go
@@ -9,10 +9,10 @@ import (
 
 func BuildDirectTarget(endpoints []string) string {
 	return fmt.Sprintf("%s:///%s", resolver.DirectScheme, strings.Join(
-		endpoints, fmt.Sprint(resolver.EndpointSep)))
+		endpoints, fmt.Sprintf("%c", resolver.EndpointSep)))
 }
 
 func BuildDiscovTarget(endpoints []string, key string) string {
 	return fmt.Sprintf("%s://%s/%s", resolver.DiscovScheme, strings.Join(
-		endpoints, fmt.Sprint(resolver.EndpointSep)), key)
+		endpoints, fmt.Sprintf("%c", resolver.EndpointSep)), key)
 }
diff --git a/rpcx/internal/target_test.go b/rpcx/internal/target_test.go
new file mode 100644
index 00000000..a07b3a8e
--- /dev/null
+++ b/rpcx/internal/target_test.go
@@ -0,0 +1,17 @@
+package internal
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestBuildDirectTarget(t *testing.T) {
+	target := BuildDirectTarget([]string{"localhost:123", "localhost:456"})
+	assert.Equal(t, "direct:///localhost:123,localhost:456", target)
+}
+
+func TestBuildDiscovTarget(t *testing.T) {
+	target := BuildDiscovTarget([]string{"localhost:123", "localhost:456"}, "foo")
+	assert.Equal(t, "discov://localhost:123,localhost:456/foo", target)
+}