Add fake Buffer for testing

Adding a class to represent the Windows Buffer class within tests, as
well as basic unit tests to validate the test class behaviors.

Bug: 1035527
Change-Id: Ib4507c66d7b9c975e7580b2053f23b1dc54f3402
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2485553
Reviewed-by: Eric Willigers <ericwilligers@chromium.org>
Commit-Queue: Hoch Hochkeppel <mhochk@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#818753}

chrome/browser/webshare/win/fake_buffer.cc

@@ -0,0 +1,38 @@
+// Copyright 2020 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 "chrome/browser/webshare/win/fake_buffer.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace webshare {
+
+FakeBuffer::FakeBuffer(UINT32 capacity) : data_(capacity) {}
+
+FakeBuffer::~FakeBuffer() = default;
+
+IFACEMETHODIMP FakeBuffer::get_Capacity(UINT32* value) {
+  *value = data_.size();
+  return S_OK;
+}
+IFACEMETHODIMP FakeBuffer::get_Length(UINT32* value) {
+  *value = length_;
+  return S_OK;
+}
+IFACEMETHODIMP FakeBuffer::put_Length(UINT32 value) {
+  if (value > data_.size()) {
+    ADD_FAILURE() << "put_Length called with a value (" << value
+                  << ") greater than the capacity (" << data_.size() << ")";
+    return E_INVALIDARG;
+  }
+  length_ = value;
+  return S_OK;
+}
+
+IFACEMETHODIMP FakeBuffer::Buffer(byte** value) {
+  *value = data_.data();
+  return S_OK;
+}
+
+}  // namespace webshare

chrome/browser/webshare/win/fake_buffer.h

@@ -0,0 +1,43 @@
+// Copyright 2020 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.
+
+#ifndef CHROME_BROWSER_WEBSHARE_WIN_FAKE_BUFFER_H_
+#define CHROME_BROWSER_WEBSHARE_WIN_FAKE_BUFFER_H_
+
+#include <robuffer.h>
+#include <windows.storage.streams.h>
+#include <wrl/implements.h>
+
+#include <vector>
+
+namespace webshare {
+
+// Provides an implementation of IBuffer for use in GTests.
+class __declspec(uuid("23BAE777-CA37-40B3-8F1C-0B86C1F43EE5")) FakeBuffer final
+    : public Microsoft::WRL::RuntimeClass<
+          Microsoft::WRL::RuntimeClassFlags<Microsoft::WRL::WinRtClassicComMix>,
+          ABI::Windows::Storage::Streams::IBuffer,
+          Windows::Storage::Streams::IBufferByteAccess> {
+ public:
+  explicit FakeBuffer(UINT32 capacity);
+  FakeBuffer(const FakeBuffer&) = delete;
+  FakeBuffer& operator=(const FakeBuffer&) = delete;
+  ~FakeBuffer() final;
+
+  // ABI::Windows::Storage::Streams::IBuffer:
+  IFACEMETHODIMP get_Capacity(UINT32* value) final;
+  IFACEMETHODIMP get_Length(UINT32* value) final;
+  IFACEMETHODIMP put_Length(UINT32 value) final;
+
+  // Windows::Storage::Streams::IBufferByteAccess
+  IFACEMETHODIMP Buffer(byte** value) final;
+
+ private:
+  std::vector<unsigned char> data_;
+  UINT32 length_ = 0;
+};
+
+}  // namespace webshare
+
+#endif  // CHROME_BROWSER_WEBSHARE_WIN_FAKE_BUFFER_H_

chrome/browser/webshare/win/fake_buffer_unittest.cc

@@ -0,0 +1,57 @@
+// Copyright 2020 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 "chrome/browser/webshare/win/fake_buffer.h"
+
+#include <wrl/implements.h>
+
+#include "testing/gtest/include/gtest/gtest-spi.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using Microsoft::WRL::Make;
+
+namespace webshare {
+
+TEST(FakeBufferTest, Length) {
+  auto buffer = Make<FakeBuffer>(47);
+
+  UINT32 capacity;
+  ASSERT_HRESULT_SUCCEEDED(buffer->get_Capacity(&capacity));
+  ASSERT_EQ(capacity, 47u);
+
+  UINT32 length;
+  ASSERT_HRESULT_SUCCEEDED(buffer->get_Length(&length));
+  ASSERT_EQ(length, 0u);
+
+  ASSERT_HRESULT_SUCCEEDED(buffer->put_Length(23));
+  ASSERT_HRESULT_SUCCEEDED(buffer->get_Length(&length));
+  ASSERT_EQ(length, 23u);
+
+  ASSERT_HRESULT_SUCCEEDED(buffer->put_Length(47));
+  ASSERT_HRESULT_SUCCEEDED(buffer->get_Length(&length));
+  ASSERT_EQ(length, 47u);
+
+  EXPECT_NONFATAL_FAILURE(ASSERT_HRESULT_FAILED(buffer->put_Length(48)),
+                          "put_Length");
+}
+
+TEST(FakeBufferTest, Bytes) {
+  auto buffer = Make<FakeBuffer>(2);
+
+  byte* raw_buffer;
+  ASSERT_HRESULT_SUCCEEDED(buffer->Buffer(&raw_buffer));
+
+  raw_buffer[0] = 'a';
+  raw_buffer[1] = 'b';
+
+  auto buffer2 = buffer;
+  byte* raw_buffer_2;
+  ASSERT_HRESULT_SUCCEEDED(buffer2->Buffer(&raw_buffer_2));
+
+  ASSERT_EQ(raw_buffer, raw_buffer_2);
+  ASSERT_EQ(raw_buffer_2[0], 'a');
+  ASSERT_EQ(raw_buffer_2[1], 'b');
+}
+
+}  // namespace webshare

chrome/test/BUILD.gn

@@ -321,6 +321,8 @@ static_library("test_support") {
 
   if (is_win) {
     sources += [
+      "../browser/webshare/win/fake_buffer.cc",
+      "../browser/webshare/win/fake_buffer.h",
       "../browser/webshare/win/fake_data_transfer_manager.cc",
       "../browser/webshare/win/fake_data_transfer_manager.h",
       "../browser/webshare/win/fake_data_transfer_manager_interop.cc",
@@ -5810,6 +5812,7 @@ test("unit_tests") {
     sources += [
       "../browser/notifications/win/notification_template_builder_unittest.cc",
       "../browser/ui/views/uninstall_view_unittest.cc",
+      "../browser/webshare/win/fake_buffer_unittest.cc",
       "../browser/webshare/win/fake_data_transfer_manager_interop_unittest.cc",
       "../browser/webshare/win/fake_data_transfer_manager_unittest.cc",
       "../browser/webshare/win/show_share_ui_for_window_operation_unittest.cc",