added gzip decompression of response body

reddit/reddit.go

@@ -2,6 +2,7 @@ package reddit
 
 import (
 	"bytes"
+	"compress/gzip"
 	"context"
 	"encoding/json"
 	"fmt"
@@ -372,27 +373,42 @@ func (c *Client) Do(ctx context.Context, req *http.Request, v interface{}) (*Res
 	c.rateMu.Unlock()
 
 	err = CheckResponse(resp)
-	if err != nil {
+	if err != nil || v == nil {
 		return response, err
 	}
 
-	if v != nil {
+	w, ok := v.(io.Writer)
-		if w, ok := v.(io.Writer); ok {
+	if ok {
 		_, err = io.Copy(w, response.Body)
 		if err != nil {
 			return response, err
 		}
+	} else {
+		if response.Header.Get("Content-Encoding") == "gzip" {
+			gzipReader, err := gzip.NewReader(resp.Body)
+			if err != nil {
+				return response, fmt.Errorf("Error creating gzip reader: %s", err)
+			}
+			defer gzipReader.Close()
+			b, err := io.ReadAll(gzipReader)
+			if err != nil {
+				return response, fmt.Errorf("Error decoding gzip json: %s", err)
+			}
+			err = json.Unmarshal(b, v)
+			if err != nil {
+				return response, fmt.Errorf("Error unmarshalling json: %s", err)
+			}
 		} else {
 			err = json.NewDecoder(response.Body).Decode(v)
 			if err != nil {
 				return response, err
 			}
 		}
+	}
 
 	if anchor, ok := v.(anchor); ok {
 		response.populateAnchors(anchor)
 	}
-	}
 
 	return response, nil
 }

reddit/reddit_test.go

@@ -1,7 +1,9 @@
 package reddit
 
 import (
+	"compress/gzip"
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io/ioutil"
@@ -271,3 +273,23 @@ func TestClient_Do_RateLimitError(t *testing.T) {
 	require.Equal(t, 600, resp.Rate.Used)
 	require.Equal(t, time.Now().Truncate(time.Second).Add(time.Minute*4), resp.Rate.Reset)
 }
+
+func TestClient_Do_Gzip(t *testing.T) {
+	client, mux := setup(t)
+	expected := map[string]string{
+		"message": "Hello!",
+	}
+	mux.HandleFunc("/api/v1/test", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("Content-Encoding", "gzip")
+		b, _ := json.Marshal(&expected)
+		zw := gzip.NewWriter(w)
+		zw.Write(b)
+		zw.Close()
+	})
+	req, err := client.NewRequest(http.MethodGet, "api/v1/test", nil)
+	require.NoError(t, err)
+	result := map[string]string{}
+	_, err = client.Do(ctx, req, &result)
+	require.NoError(t, err)
+	require.Equal(t, result, expected)
+}