Fix shouldRetry behavior for nested errors

CHANGELOG_PENDING.md

@@ -3,3 +3,4 @@
 ### SDK Enhancements
 
 ### SDK Bugs
+* `aws/request`: Fix shouldRetry behavior for nested errors ([#3017](https://github.com/aws/aws-sdk-go/pull/3017))

aws/request/retryer.go

@@ -177,7 +177,7 @@ func shouldRetryError(origErr error) bool {
 		origErr := err.OrigErr()
 		var shouldRetry bool
 		if origErr != nil {
-			shouldRetry := shouldRetryError(origErr)
+			shouldRetry = shouldRetryError(origErr)
 			if err.Code() == "RequestError" && !shouldRetry {
 				return false
 			}

aws/request/retryer_test.go

@@ -76,7 +76,7 @@ func TestIsErrorRetryable(t *testing.T) {
 		},
 		{
 			Err:       awserr.New(ErrCodeSerialization, "some error", errors.New("blah")),
-			Retryable: false,
+			Retryable: true,
 		},
 		{
 			Err:       awserr.New("SomeError", "some error", nil),

service/s3/s3manager/download_test.go

@@ -2,6 +2,7 @@ package s3manager_test
 
 import (
 	"bytes"
+	"encoding/xml"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -101,9 +102,19 @@ func dlLoggingSvcNoContentRangeLength(data []byte, states []int) (*s3.S3, *[]str
 
 		names = append(names, r.Operation.Name)
 
+		var body io.Reader
+		if states[index] < 400 {
+			body = bytes.NewReader(data[:])
+		} else {
+			var buffer bytes.Buffer
+			encoder := xml.NewEncoder(&buffer)
+			_ = encoder.Encode(&mockErrorResponse)
+			body = &buffer
+		}
+
 		r.HTTPResponse = &http.Response{
 			StatusCode: states[index],
-			Body:       ioutil.NopCloser(bytes.NewReader(data[:])),
+			Body:       ioutil.NopCloser(body),
 			Header:     http.Header{},
 		}
 		index++
@@ -840,3 +851,12 @@ func (b *badReader) Read(p []byte) (int, error) {
 
 	return len(p), b.err
 }
+
+var mockErrorResponse = struct {
+	XMLName xml.Name `xml:"Error"`
+	Code    string   `xml:"Code"`
+	Message string   `xml:"Message"`
+}{
+	Code:    "MOCK_S3_ERROR_CODE",
+	Message: "Mocked S3 Error Message",
+}