goprotobuf: Add a Size function.

R=r
CC=golang-dev
http://codereview.appspot.com/6812097
diff --git a/proto/size_test.go b/proto/size_test.go
new file mode 100644
index 0000000..31aaf54
--- /dev/null
+++ b/proto/size_test.go
@@ -0,0 +1,107 @@
+// Go support for Protocol Buffers - Google's data interchange format
+//
+// Copyright 2012 Google Inc.  All rights reserved.
+// http://code.google.com/p/goprotobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package proto_test
+
+import (
+	"log"
+	"testing"
+
+	pb "./testdata"
+	. "code.google.com/p/goprotobuf/proto"
+)
+
+var messageWithExtension1 = &pb.MyMessage{Count: Int32(7)}
+var messageWithExtension3 = &pb.MyMessage{Count: Int32(8)}
+
+func init() {
+	if err := SetExtension(messageWithExtension1, pb.E_Ext_More, &pb.Ext{Data: String("Abbott")}); err != nil {
+		log.Panicf("SetExtension: %v", err)
+	}
+	if err := SetExtension(messageWithExtension3, pb.E_Ext_More, &pb.Ext{Data: String("Costello")}); err != nil {
+		log.Panicf("SetExtension: %v", err)
+	}
+
+	// Force messageWithExtension3 to have the extension encoded.
+	Marshal(messageWithExtension3)
+}
+
+var SizeTests = []struct {
+	desc string
+	pb   Message
+}{
+	{"empty", &pb.OtherMessage{}},
+	// Basic types.
+	{"bool", &pb.Defaults{F_Bool: Bool(true)}},
+	{"int32", &pb.Defaults{F_Int32: Int32(12)}},
+	{"small int64", &pb.Defaults{F_Int64: Int64(1)}},
+	{"big int64", &pb.Defaults{F_Int64: Int64(1 << 20)}},
+	{"fixed32", &pb.Defaults{F_Fixed32: Uint32(71)}},
+	{"fixed64", &pb.Defaults{F_Fixed64: Uint64(72)}},
+	{"uint32", &pb.Defaults{F_Uint32: Uint32(123)}},
+	{"uint64", &pb.Defaults{F_Uint64: Uint64(124)}},
+	{"float", &pb.Defaults{F_Float: Float32(12.6)}},
+	{"double", &pb.Defaults{F_Double: Float64(13.9)}},
+	{"string", &pb.Defaults{F_String: String("niles")}},
+	{"bytes", &pb.Defaults{F_Bytes: []byte("wowsa")}},
+	{"bytes, empty", &pb.Defaults{F_Bytes: []byte{}}},
+	{"sint32", &pb.Defaults{F_Sint32: Int32(65)}},
+	{"sint64", &pb.Defaults{F_Sint64: Int64(67)}},
+	{"enum", &pb.Defaults{F_Enum: pb.Defaults_BLUE.Enum()}},
+	// Repeated.
+	{"empty repeated bool", &pb.MoreRepeated{Bools: []bool{}}},
+	{"repeated bool", &pb.MoreRepeated{Bools: []bool{false, true, true, false}}},
+	{"packed repeated bool", &pb.MoreRepeated{BoolsPacked: []bool{false, true, true, false, true, true, true}}},
+	{"repeated int32", &pb.MoreRepeated{Ints: []int32{1, 12203, 1729}}},
+	{"repeated int32 packed", &pb.MoreRepeated{IntsPacked: []int32{1, 12203, 1729}}},
+	{"repeated string", &pb.MoreRepeated{Strings: []string{"r", "ken", "gri"}}},
+	// Nested.
+	{"nested", &pb.OldMessage{Nested: &pb.OldMessage_Nested{Name: String("whatever")}}},
+	// Other things.
+	{"unrecognized", &pb.MoreRepeated{XXX_unrecognized: []byte{13<<3 | 0, 4}}},
+	{"extension (unencoded)", messageWithExtension1},
+	{"extension (encoded)", messageWithExtension3},
+}
+
+func TestSize(t *testing.T) {
+	for _, tc := range SizeTests {
+		size := Size(tc.pb)
+		b, err := Marshal(tc.pb)
+		if err != nil {
+			t.Errorf("%v: Marshal failed: %v", tc.desc, err)
+			continue
+		}
+		if size != len(b) {
+			t.Errorf("%v: Size(%v) = %d, want %d", tc.desc, tc.pb, size, len(b))
+			t.Logf("%v: bytes: %#v", tc.desc, b)
+		}
+	}
+}