From e0b192b3d208f344d7a5c9ec3424fe93d23fef13 Mon Sep 17 00:00:00 2001
From: SystemGlitch <jeremy.la@outlook.fr>
Date: Mon, 30 Sep 2024 23:15:37 +0200
Subject: [PATCH] fix: HTTP response error handling #42 (#43)

---
 resend.go      |  22 +++++++---
 resend_test.go | 106 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 122 insertions(+), 6 deletions(-)

diff --git a/resend.go b/resend.go
index 01f21cf..baab835 100644
--- a/resend.go
+++ b/resend.go
@@ -144,18 +144,28 @@ func handleError(resp *http.Response) error {
 	// Handles errors most likely caused by the client
 	case http.StatusUnprocessableEntity, http.StatusBadRequest:
 		r := &InvalidRequestError{}
-		err := json.NewDecoder(resp.Body).Decode(r)
-		if err != nil {
-			return err
+		if strings.HasPrefix(resp.Header.Get("Content-Type"), "application/json") {
+			err := json.NewDecoder(resp.Body).Decode(r)
+			if err != nil {
+				r.Message = resp.Status
+			}
+		} else {
+			r.Message = resp.Status
 		}
 		return errors.New("[ERROR]: " + r.Message)
 	default:
 		// Tries to parse `message` attr from error
 		r := &DefaultError{}
-		err := json.NewDecoder(resp.Body).Decode(r)
-		if err != nil {
-			return err
+
+		if strings.HasPrefix(resp.Header.Get("Content-Type"), "application/json") {
+			err := json.NewDecoder(resp.Body).Decode(r)
+			if err != nil {
+				r.Message = resp.Status
+			}
+		} else {
+			r.Message = resp.Status
 		}
+
 		if r.Message != "" {
 			return errors.New("[ERROR]: " + r.Message)
 		}
diff --git a/resend_test.go b/resend_test.go
index 6773c24..bbef1a7 100644
--- a/resend_test.go
+++ b/resend_test.go
@@ -1,8 +1,11 @@
 package resend
 
 import (
+	"bytes"
 	"context"
 	"errors"
+	"fmt"
+	"io"
 	"net/http"
 	"testing"
 
@@ -44,3 +47,106 @@ func TestResendRequestShouldReturnErrorIfContextIsCancelled(t *testing.T) {
 	assert.True(t, errors.Unwrap(err) == context.Canceled)
 	assert.Nil(t, res)
 }
+
+func TestHandleError(t *testing.T) {
+	cases := []struct {
+		desc string
+		resp *http.Response
+		want error
+	}{
+		{
+			desc: "validation_error",
+			resp: &http.Response{
+				StatusCode: http.StatusUnprocessableEntity,
+				Status:     fmt.Sprintf("%d %s", http.StatusUnprocessableEntity, http.StatusText(http.StatusUnprocessableEntity)),
+				Header:     http.Header{"Content-Type": {"application/json; charset=utf-8"}},
+				Body:       io.NopCloser(bytes.NewBufferString(`{"message":"Validation error"}`)),
+			},
+			want: errors.New("[ERROR]: Validation error"),
+		},
+		{
+			desc: "validation_error_no_json",
+			resp: &http.Response{
+				StatusCode: http.StatusUnprocessableEntity,
+				Status:     fmt.Sprintf("%d %s", http.StatusUnprocessableEntity, http.StatusText(http.StatusUnprocessableEntity)),
+				Body:       io.NopCloser(bytes.NewBufferString(`Validation error`)),
+			},
+			want: errors.New("[ERROR]: 422 Unprocessable Entity"),
+		},
+		{
+			desc: "bad_request",
+			resp: &http.Response{
+				StatusCode: http.StatusBadRequest,
+				Status:     fmt.Sprintf("%d %s", http.StatusBadRequest, http.StatusText(http.StatusBadRequest)),
+				Header:     http.Header{"Content-Type": {"application/json; charset=utf-8"}},
+				Body:       io.NopCloser(bytes.NewBufferString(`{"message":"Validation error"}`)),
+			},
+			want: errors.New("[ERROR]: Validation error"),
+		},
+		{
+			desc: "bad_request_no_json",
+			resp: &http.Response{
+				StatusCode: http.StatusBadRequest,
+				Status:     fmt.Sprintf("%d %s", http.StatusBadRequest, http.StatusText(http.StatusBadRequest)),
+				Body:       io.NopCloser(bytes.NewBufferString(`Validation error`)),
+			},
+			want: errors.New("[ERROR]: 400 Bad Request"),
+		},
+		{
+			desc: "bad_request_invalid_json",
+			resp: &http.Response{
+				StatusCode: http.StatusBadRequest,
+				Status:     fmt.Sprintf("%d %s", http.StatusBadRequest, http.StatusText(http.StatusBadRequest)),
+				Header:     http.Header{"Content-Type": {"application/json; charset=utf-8"}},
+				Body:       io.NopCloser(bytes.NewBufferString(`{`)),
+			},
+			want: errors.New("[ERROR]: 400 Bad Request"),
+		},
+		{
+			desc: "server_error",
+			resp: &http.Response{
+				StatusCode: http.StatusInternalServerError,
+				Status:     fmt.Sprintf("%d %s", http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError)),
+				Header:     http.Header{"Content-Type": {"application/json; charset=utf-8"}},
+				Body:       io.NopCloser(bytes.NewBufferString(`{"message":"Server error"}`)),
+			},
+			want: errors.New("[ERROR]: Server error"),
+		},
+		{
+			desc: "server_error_no_json",
+			resp: &http.Response{
+				StatusCode: http.StatusInternalServerError,
+				Status:     fmt.Sprintf("%d %s", http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError)),
+				Body:       io.NopCloser(bytes.NewBufferString(`Server error`)),
+			},
+			want: errors.New("[ERROR]: 500 Internal Server Error"),
+		},
+		{
+			desc: "server_error_invalid_json",
+			resp: &http.Response{
+				StatusCode: http.StatusInternalServerError,
+				Status:     fmt.Sprintf("%d %s", http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError)),
+				Header:     http.Header{"Content-Type": {"application/json; charset=utf-8"}},
+				Body:       io.NopCloser(bytes.NewBufferString(`{`)),
+			},
+			want: errors.New("[ERROR]: 500 Internal Server Error"),
+		},
+		{
+			desc: "server_error_no_message",
+			resp: &http.Response{
+				StatusCode: http.StatusInternalServerError,
+				Status:     fmt.Sprintf("%d %s", http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError)),
+				Header:     http.Header{"Content-Type": {"application/json; charset=utf-8"}},
+				Body:       io.NopCloser(bytes.NewBufferString(`{}`)),
+			},
+			want: errors.New("[ERROR]: Unknown Error"),
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(c.desc, func(t *testing.T) {
+			err := handleError(c.resp)
+			assert.Equal(t, c.want, err)
+		})
+	}
+}