From c1e9fd594dd2306e803a23b0f7e0e26f704c437d Mon Sep 17 00:00:00 2001
From: Tyschitskaya Maria <tyschitskaya@retailcrm.ru>
Date: Thu, 27 Jan 2022 17:17:20 +0300
Subject: [PATCH] buffer from decoder in unmarshal error

---
 response.go      | 11 ++++++-----
 response_test.go |  6 ++++--
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/response.go b/response.go
index d5bca94..a7a0502 100644
--- a/response.go
+++ b/response.go
@@ -87,9 +87,10 @@ func checkFacebookError(r io.Reader) error {
 	var err error
 
 	qr := QueryResponse{}
-	err = json.NewDecoder(r).Decode(&qr)
+	decoder := json.NewDecoder(r)
+	err = decoder.Decode(&qr)
 	if err != nil {
-		return NewUnmarshalError().WithReader(r)
+		return NewUnmarshalError().WithReader(decoder.Buffered())
 	}
 	if qr.Error != nil {
 		return xerrors.Errorf("facebook error: %w", qr.Error)
@@ -100,9 +101,9 @@ func checkFacebookError(r io.Reader) error {
 
 func getFacebookQueryResponse(r io.Reader) (QueryResponse, error) {
 	qr := QueryResponse{}
-	err := json.NewDecoder(r).Decode(&qr)
-	if err != nil {
-		return qr, NewUnmarshalError().WithReader(r)
+	decoder := json.NewDecoder(r)
+	if err := decoder.Decode(&qr); err != nil {
+		return qr, NewUnmarshalError().WithReader(decoder.Buffered())
 	}
 	if qr.Error != nil {
 		return qr, xerrors.Errorf("facebook error: %w", qr.Error)
diff --git a/response_test.go b/response_test.go
index f15663e..258b639 100644
--- a/response_test.go
+++ b/response_test.go
@@ -19,13 +19,15 @@ func Test_MarshalStructuredMessageElement(t *testing.T) {
 }
 
 func TestResponse_checkFacebookError_UnmarshalError(t *testing.T) {
-	r := bytes.NewReader([]byte("test"))
+	r := bytes.NewReader([]byte("test error text"))
 	err := checkFacebookError(r)
 	assert.True(t, errors.Is(err, ErrUnmarshal))
+	assert.Contains(t, err.Error(), "test error text")
 }
 
 func TestResponse_getFacebookQueryResponse_UnmarshalError(t *testing.T) {
-	r := bytes.NewReader([]byte("test"))
+	r := bytes.NewReader([]byte("test error text"))
 	_, err := getFacebookQueryResponse(r)
 	assert.True(t, errors.Is(err, ErrUnmarshal))
+	assert.Contains(t, err.Error(), "test error text")
 }