code review 13651044: bytes: additional test coverage

src/pkg/bytes/reader_test.go

 // Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package bytes_test
 
 import (
         . "bytes"
         "fmt"
         "io"
@@ skipping 95 matching lines @@
                 }
                 if b.String() != s {
                         t.Errorf("got string %q; want %q", b.String(), s)
                 }
                 if r.Len() != 0 {
                         t.Errorf("reader contains %v bytes; want 0", r.Len())
                 }
         }
 }
 
+func TestReaderLen(t *testing.T) {
+        const data = "hello world"
+        r := NewReader([]byte(data))
+        if actual, expected := r.Len(), 11; actual != expected {
+                t.Errorf("r.Len(): expected %d bytes, got %v", expected, actual)
+        }
+        if n, err := r.Read(make([]byte, 10)); err != nil || n != 10 {
+                t.Errorf("Read failed: read %d %v", n, err)
+        }
+        if actual, expected := r.Len(), 1; actual != expected {

[bradfitz, 2013/09/11 10:51:20]

a/actual, expected/got, want/

[dave_cheney.net, 2013/09/11 11:06:20]

Done.

+                t.Errorf("r.Len(): expected %d bytes, got %v", expected, actual)

[bradfitz, 2013/09/11 10:51:20]

got first, then want:

"Len = %d; want %d", got, want

[dave_cheney.net, 2013/09/11 11:06:20]

Done.

+        }
+        if n, err := r.Read(make([]byte, 1)); err != nil || n != 1 {
+                t.Errorf("Read failed: read %d %v", n, err)
+        }
+        if actual, expected := r.Len(), 0; actual != expected {

[bradfitz, 2013/09/11 10:51:20]

etc

[dave_cheney.net, 2013/09/11 11:06:20]

Done.

+                t.Errorf("r.Len(): expected %d bytes, got %v", expected, actual)
+        }
+}
+
+func TestReaderDoubleUnreadRune(t *testing.T) {
+        buf := NewBuffer([]byte("groucho"))
+        if _, _, err := buf.ReadRune(); err != nil {
+                // should not happen
+                t.Fatal(err)
+        }
+        if err := buf.UnreadByte(); err != nil {
+                // should not happen
+                t.Fatal(err)
+        }
+        if err := buf.UnreadByte(); err == nil {
+                t.Fatal("UnreadByte: expected error, got nil")
+        }
+}
+
 // verify that copying from an empty reader always has the same results,
 // regardless of the presence of a WriteTo method.
 func TestReaderCopyNothing(t *testing.T) {
         type nErr struct {
                 n   int64
                 err error
         }
         type justReader struct {
                 io.Reader
         }
         type justWriter struct {
                 io.Writer
         }
         discard := justWriter{ioutil.Discard} // hide ReadFrom
 
         var with, withOut nErr
         with.n, with.err = io.Copy(discard, NewReader(nil))
         withOut.n, withOut.err = io.Copy(discard, justReader{NewReader(nil)})
         if with != withOut {
                 t.Errorf("behavior differs: with = %#v; without: %#v", with, withOut)
         }
 }