1 files changed, 13 insertions, 0 deletions
diff --git a/llgo/third_party/gofrontend/libgo/go/strings/reader_test.go b/llgo/third_party/gofrontend/libgo/go/strings/reader_test.go
index bee90eb2585..5003a37be48 100644
--- a/llgo/third_party/gofrontend/libgo/go/strings/reader_test.go
+++ b/llgo/third_party/gofrontend/libgo/go/strings/reader_test.go
@@ -8,6 +8,7 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
 	"strings"
 	"sync"
@@ -157,3 +158,15 @@ func TestWriteTo(t *testing.T) {
 		}
 	}
 }
+
+// tests that Len is affected by reads, but Size is not.
+func TestReaderLenSize(t *testing.T) {
+	r := strings.NewReader("abc")
+	io.CopyN(ioutil.Discard, r, 1)
+	if r.Len() != 2 {
+		t.Errorf("Len = %d; want 2", r.Len())
+	}
+	if r.Size() != 3 {
+		t.Errorf("Size = %d; want 3", r.Size())
+	}
+}