[TrueCloudLab#40] Add param to configure xml decoder

This parameter enables parsing xml body without
xmlns="http://s3.amazonaws.com/doc/2006-03-01/" attribute
for CompleteMultipartUpload requests

Signed-off-by: Denis Kirillov <d.kirillov@yadro.com>

internal/xml/decoder_test.go

@@ -0,0 +1,83 @@
+package xml
+
+import (
+	"bytes"
+	"testing"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/handler"
+	"github.com/stretchr/testify/require"
+)
+
+func TestDefaultNamespace(t *testing.T) {
+	xmlBodyWithNamespace := `
+ <CompleteMultipartUpload xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
+   <Part>
+      <ETag>string</ETag>
+      <PartNumber>1</PartNumber>
+   </Part>
+</CompleteMultipartUpload>
+`
+	xmlBodyWithInvalidNamespace := `
+ <CompleteMultipartUpload xmlns="http://bla.bla.bla/">
+   <Part>
+      <ETag>string</ETag>
+      <PartNumber>1</PartNumber>
+   </Part>
+</CompleteMultipartUpload>
+`
+	xmlBody := `
+ <CompleteMultipartUpload>
+   <Part>
+      <ETag>string</ETag>
+      <PartNumber>1</PartNumber>
+   </Part>
+</CompleteMultipartUpload>
+`
+
+	for _, tc := range []struct {
+		provider *DecoderProvider
+		input    string
+		err      bool
+	}{
+		{
+			provider: NewDecoderProvider(false),
+			input:    xmlBodyWithNamespace,
+			err:      false,
+		},
+		{
+			provider: NewDecoderProvider(false),
+			input:    xmlBody,
+			err:      true,
+		},
+		{
+			provider: NewDecoderProvider(false),
+			input:    xmlBodyWithInvalidNamespace,
+			err:      true,
+		},
+		{
+			provider: NewDecoderProvider(true),
+			input:    xmlBodyWithNamespace,
+			err:      false,
+		},
+		{
+			provider: NewDecoderProvider(true),
+			input:    xmlBody,
+			err:      false,
+		},
+		{
+			provider: NewDecoderProvider(true),
+			input:    xmlBodyWithInvalidNamespace,
+			err:      true,
+		},
+	} {
+		t.Run("", func(t *testing.T) {
+			model := new(handler.CompleteMultipartUpload)
+			err := tc.provider.NewCompleteMultipartDecoder(bytes.NewBufferString(tc.input)).Decode(model)
+			if tc.err {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+			}
+		})
+	}
+}