diff --git a/encoding/form/well_known_types_test.go b/encoding/form/well_known_types_test.go
new file mode 100644
index 000000000..5598211b0
--- /dev/null
+++ b/encoding/form/well_known_types_test.go
@@ -0,0 +1,95 @@
+package form
+
+import (
+	"encoding/base64"
+	"testing"
+	"time"
+
+	"google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/types/known/durationpb"
+	"google.golang.org/protobuf/types/known/timestamppb"
+	"google.golang.org/protobuf/types/known/wrapperspb"
+)
+
+func TestMarshalTimeStamp(t *testing.T) {
+	tests := []struct {
+		input  *timestamppb.Timestamp
+		expect string
+	}{
+		{
+			input:  timestamppb.New(time.Date(2022, 1, 2, 3, 4, 5, 6, time.UTC)),
+			expect: "2022-01-02T03:04:05.000000006Z",
+		},
+		{
+			input:  timestamppb.New(time.Date(2022, 13, 1, 13, 61, 61, 100, time.UTC)),
+			expect: "2023-01-01T14:02:01.000000100Z",
+		},
+	}
+	for _, v := range tests {
+		content, err := marshalTimestamp(v.input.ProtoReflect())
+		if err != nil {
+			t.Errorf("expect %v,got %v", nil, err)
+		}
+		if got, want := content, v.expect; got != want {
+			t.Errorf("expect %v,got %v", want, got)
+		}
+	}
+}
+
+func TestMarshalDuration(t *testing.T) {
+	tests := []struct {
+		input  *durationpb.Duration
+		expect string
+	}{
+		{
+			input:  durationpb.New(time.Duration(1<<63 - 1)),
+			expect: "2562047h47m16.854775807s",
+		},
+		{
+			input:  durationpb.New(time.Duration(-1 << 63)),
+			expect: "-2562047h47m16.854775808s",
+		},
+		{
+			input:  durationpb.New(100 * time.Second),
+			expect: "1m40s",
+		},
+		{
+			input:  durationpb.New(-100 * time.Second),
+			expect: "-1m40s",
+		},
+	}
+	for _, v := range tests {
+		content, err := marshalDuration(v.input.ProtoReflect())
+		if err != nil {
+			t.Errorf("expect %v,got %v", nil, err)
+		}
+		if got, want := content, v.expect; got != want {
+			t.Errorf("expect %v,got %v", want, got)
+		}
+	}
+}
+
+func TestMarshalBytes(t *testing.T) {
+	tests := []struct {
+		input  protoreflect.Message
+		expect string
+	}{
+		{
+			input:  wrapperspb.Bytes([]byte("abc123!?$*&()'-=@~")).ProtoReflect(),
+			expect: base64.StdEncoding.EncodeToString([]byte("abc123!?$*&()'-=@~")),
+		},
+		{
+			input:  wrapperspb.Bytes([]byte("kratos")).ProtoReflect(),
+			expect: base64.StdEncoding.EncodeToString([]byte("kratos")),
+		},
+	}
+	for _, v := range tests {
+		content, err := marshalBytes(v.input)
+		if err != nil {
+			t.Errorf("expect %v,got %v", nil, err)
+		}
+		if got, want := content, v.expect; got != want {
+			t.Errorf("expect %v,got %v", want, got)
+		}
+	}
+}