Add a basic backwards compatibility unittest.

courgette/versioning_unittest.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "courgette/base_test_unittest.h"
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "courgette/courgette.h"
+#include "courgette/streams.h"
+
+class VersioningTest : public BaseTest {
+ public:
+  void TestApplyingOldPatch(const char* src_file,
+                         const char* patch_file,
+                         const char* expected_file) const;
+};
+
+void VersioningTest::TestApplyingOldPatch(const char* src_file,
+                                          const char* patch_file,
+                                          const char* expected_file) const {
+
+  std::string old_buffer = FileContents(src_file);
+  std::string new_buffer = FileContents(patch_file);
+  std::string expected_buffer = FileContents(expected_file);
+
+  courgette::SourceStream old_stream;
+  courgette::SourceStream patch_stream;
+  old_stream.Init(old_buffer);
+  patch_stream.Init(new_buffer);
+
+  courgette::SinkStream generated_stream;
+
+  courgette::Status status =
+      courgette::ApplyEnsemblePatch(&old_stream,
+                                    &patch_stream,
+                                    &generated_stream);
+
+  EXPECT_EQ(status, courgette::C_OK);
+
+  size_t expected_length = expected_buffer.size();
+  size_t generated_length = generated_stream.Length();
+
+  EXPECT_EQ(generated_length, expected_length);
+  EXPECT_EQ(0, memcmp(generated_stream.Buffer(),
+                      expected_buffer.c_str(),
+                      expected_length));
+}
+
+
+TEST_F(VersioningTest, All) {
+  TestApplyingOldPatch("setup1.exe", "setup1-setup2.v1.patch", "setup2.exe");
+
+  // We also need a way to test that newly generated patches are appropriately
+  // applicable by older clients... not sure of the best way to do that.
+}