GODRIVER-1456 make extJSONValueWriter escape keys (#270)

Author: iwysiu

bson/bson_test.go

@@ -111,3 +111,21 @@ func TestD(t *testing.T) {
 		}
 	})
 }
+
+func TestExtJSONEscapeKey(t *testing.T) {
+	doc := D{{Key: "\\usb#", Value: int32(1)}}
+	b, err := MarshalExtJSON(&doc, false, false)
+	noerr(t, err)
+
+	want := "{\"\\\\usb#\":1}"
+	if diff := cmp.Diff(want, string(b)); diff != "" {
+		t.Errorf("Marshaled documents do not match. got %v, want %v", string(b), want)
+	}
+
+	var got D
+	err = UnmarshalExtJSON(b, false, &got)
+	noerr(t, err)
+	if !cmp.Equal(got, doc) {
+		t.Errorf("Unmarshaled documents do not match. got %v; want %v", got, doc)
+	}
+}

bson/bsonrw/extjson_writer.go

@@ -536,7 +536,10 @@ func (ejvw *extJSONValueWriter) WriteUndefined() error {
 func (ejvw *extJSONValueWriter) WriteDocumentElement(key string) (ValueWriter, error) {
 	switch ejvw.stack[ejvw.frame].mode {
 	case mDocument, mTopLevel, mCodeWithScope:
-		ejvw.buf = append(ejvw.buf, []byte(fmt.Sprintf(`"%s":`, key))...)
+		var buf bytes.Buffer
+		writeStringWithEscapes(key, &buf, ejvw.escapeHTML)
+
+		ejvw.buf = append(ejvw.buf, []byte(fmt.Sprintf(`%s:`, buf.String()))...)
 		ejvw.push(mElement)
 	default:
 		return nil, ejvw.invalidTransitionErr(mElement, "WriteDocumentElement", []mode{mDocument, mTopLevel, mCodeWithScope})