From f4c9d3d85cd981dede82b5278e79dc9269cd7edc Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Tue, 15 Mar 2022 11:14:11 -0700
Subject: [PATCH 01/16] Work around background clipboard error

---
 shell/platform/windows/platform_handler_win32.cc | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/shell/platform/windows/platform_handler_win32.cc b/shell/platform/windows/platform_handler_win32.cc
index 7f3b885748d88..b0f27905b546a 100644
--- a/shell/platform/windows/platform_handler_win32.cc
+++ b/shell/platform/windows/platform_handler_win32.cc
@@ -14,6 +14,7 @@
 #include "flutter/shell/platform/windows/flutter_windows_view.h"
 
 static constexpr char kValueKey[] = "value";
+static constexpr int kAccessDeniedErrorCode = 5;
 
 namespace flutter {
 
@@ -235,18 +236,27 @@ void PlatformHandlerWin32::GetPlainText(
 void PlatformHandlerWin32::GetHasStrings(
     std::unique_ptr<MethodResult<rapidjson::Document>> result) {
   ScopedClipboard clipboard;
+  bool hasStrings;
   if (!clipboard.Open(std::get<HWND>(*view_->GetRenderTarget()))) {
     rapidjson::Document error_code;
     error_code.SetInt(::GetLastError());
-    result->Error(kClipboardError, "Unable to open clipboard", error_code);
-    return;
+    // Swallow errors of type ERROR_ACCESS_DENIED. These happen when the app is
+    // not in the foreground and HasStrings is irrelevant.
+    // See https://github.com/flutter/flutter/issues/95817.
+    if (error_code != kAccessDeniedErrorCode) {
+      result->Error(kClipboardError, "Unable to open clipboard", error_code);
+      return;
+    }
+    hasStrings = false;
+  } else {
+    hasStrings = clipboard.HasString();
   }
 
   rapidjson::Document document;
   document.SetObject();
   rapidjson::Document::AllocatorType& allocator = document.GetAllocator();
   document.AddMember(rapidjson::Value(kValueKey, allocator),
-                     rapidjson::Value(clipboard.HasString()), allocator);
+                     rapidjson::Value(hasStrings), allocator);
   result->Success(document);
 }
 

From b92feedf276f484af6aa7400338a70eda68cc2f5 Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Fri, 25 Mar 2022 11:45:55 -0700
Subject: [PATCH 02/16] ScopeClipboard returns error codes and internalizes the
 error swallowing logic from this PR

---
 .../windows/platform_handler_win32.cc         | 83 +++++++++++--------
 1 file changed, 50 insertions(+), 33 deletions(-)

diff --git a/shell/platform/windows/platform_handler_win32.cc b/shell/platform/windows/platform_handler_win32.cc
index b0f27905b546a..7cf245c253f72 100644
--- a/shell/platform/windows/platform_handler_win32.cc
+++ b/shell/platform/windows/platform_handler_win32.cc
@@ -105,27 +105,25 @@ class ScopedClipboard {
   ScopedClipboard(ScopedClipboard const&) = delete;
   ScopedClipboard& operator=(ScopedClipboard const&) = delete;
 
-  // Attempts to open the clipboard for the given window, returning true if
-  // successful.
-  bool Open(HWND window);
+  // Attempts to open the clipboard for the given window, returning the error
+  // code in the case of failure and -1 otherwise.
+  int Open(HWND window);
 
   // Returns true if there is string data available to get.
   bool HasString();
 
   // Returns string data from the clipboard.
   //
-  // If getting a string fails, returns no value. Get error information with
-  // ::GetLastError().
+  // If getting a string fails, returns the error code.
   //
   // Open(...) must have succeeded to call this method.
-  std::optional<std::wstring> GetString();
+  std::variant<std::wstring, int> GetString();
 
-  // Sets the string content of the clipboard, returning true on success.
-  //
-  // On failure, get error information with ::GetLastError().
+  // Sets the string content of the clipboard, returning the error code on
+  // failure and -1 otherwise.
   //
   // Open(...) must have succeeded to call this method.
-  bool SetString(const std::wstring string);
+  int SetString(const std::wstring string);
 
  private:
   bool opened_ = false;
@@ -139,9 +137,20 @@ ScopedClipboard::~ScopedClipboard() {
   }
 }
 
-bool ScopedClipboard::Open(HWND window) {
+int ScopedClipboard::Open(HWND window) {
   opened_ = ::OpenClipboard(window);
-  return opened_;
+
+  if (!opened_) {
+    int error_code = ::GetLastError();
+    // Swallow errors of type ERROR_ACCESS_DENIED. These happen when the app is
+    // not in the foreground and HasStrings is irrelevant.
+    // See https://github.com/flutter/flutter/issues/95817.
+    if (error_code != kAccessDeniedErrorCode) {
+      return error_code;
+    }
+  }
+
+  return -1;
 }
 
 bool ScopedClipboard::HasString() {
@@ -150,24 +159,28 @@ bool ScopedClipboard::HasString() {
          ::IsClipboardFormatAvailable(CF_TEXT);
 }
 
-std::optional<std::wstring> ScopedClipboard::GetString() {
+std::variant<std::wstring, int> ScopedClipboard::GetString() {
   assert(opened_);
 
   HANDLE data = ::GetClipboardData(CF_UNICODETEXT);
   if (data == nullptr) {
-    return std::nullopt;
+    return ::GetLastError();
   }
   ScopedGlobalLock locked_data(data);
   if (!locked_data.get()) {
-    return std::nullopt;
+    return ::GetLastError();
+  }
+  std::optional<std::wstring> string = static_cast<wchar_t*>(locked_data.get());
+  if (!string) {
+    return ::GetLastError();
   }
-  return std::optional<std::wstring>(static_cast<wchar_t*>(locked_data.get()));
+  return string.value();
 }
 
-bool ScopedClipboard::SetString(const std::wstring string) {
+int ScopedClipboard::SetString(const std::wstring string) {
   assert(opened_);
   if (!::EmptyClipboard()) {
-    return false;
+    return ::GetLastError();
   }
   size_t null_terminated_byte_count =
       sizeof(decltype(string)::traits_type::char_type) * (string.size() + 1);
@@ -175,15 +188,15 @@ bool ScopedClipboard::SetString(const std::wstring string) {
                                         null_terminated_byte_count);
   ScopedGlobalLock locked_memory(destination_memory.get());
   if (!locked_memory.get()) {
-    return false;
+    return ::GetLastError();
   }
   memcpy(locked_memory.get(), string.c_str(), null_terminated_byte_count);
   if (!::SetClipboardData(CF_UNICODETEXT, locked_memory.get())) {
-    return false;
+    return ::GetLastError();
   }
   // The clipboard now owns the global memory.
   destination_memory.release();
-  return true;
+  return -1;
 }
 
 }  // namespace
@@ -205,9 +218,10 @@ void PlatformHandlerWin32::GetPlainText(
     std::unique_ptr<MethodResult<rapidjson::Document>> result,
     std::string_view key) {
   ScopedClipboard clipboard;
-  if (!clipboard.Open(std::get<HWND>(*view_->GetRenderTarget()))) {
+  int open_result = clipboard.Open(std::get<HWND>(*view_->GetRenderTarget()));
+  if (open_result != -1) {
     rapidjson::Document error_code;
-    error_code.SetInt(::GetLastError());
+    error_code.SetInt(open_result);
     result->Error(kClipboardError, "Unable to open clipboard", error_code);
     return;
   }
@@ -215,10 +229,10 @@ void PlatformHandlerWin32::GetPlainText(
     result->Success(rapidjson::Document());
     return;
   }
-  std::optional<std::wstring> clipboard_string = clipboard.GetString();
-  if (!clipboard_string) {
+  std::variant<std::wstring, int> get_string_result = clipboard.GetString();
+  if (std::holds_alternative<int>(get_string_result)) {
     rapidjson::Document error_code;
-    error_code.SetInt(::GetLastError());
+    error_code.SetInt(std::get<int>(get_string_result));
     result->Error(kClipboardError, "Unable to get clipboard data", error_code);
     return;
   }
@@ -228,7 +242,7 @@ void PlatformHandlerWin32::GetPlainText(
   rapidjson::Document::AllocatorType& allocator = document.GetAllocator();
   document.AddMember(
       rapidjson::Value(key.data(), allocator),
-      rapidjson::Value(fml::WideStringToUtf8(*clipboard_string), allocator),
+      rapidjson::Value(fml::WideStringToUtf8(std::get<std::wstring>(get_string_result)), allocator),
       allocator);
   result->Success(document);
 }
@@ -237,9 +251,10 @@ void PlatformHandlerWin32::GetHasStrings(
     std::unique_ptr<MethodResult<rapidjson::Document>> result) {
   ScopedClipboard clipboard;
   bool hasStrings;
-  if (!clipboard.Open(std::get<HWND>(*view_->GetRenderTarget()))) {
+  int open_result = clipboard.Open(std::get<HWND>(*view_->GetRenderTarget()));
+  if (open_result != -1) {
     rapidjson::Document error_code;
-    error_code.SetInt(::GetLastError());
+    error_code.SetInt(open_result);
     // Swallow errors of type ERROR_ACCESS_DENIED. These happen when the app is
     // not in the foreground and HasStrings is irrelevant.
     // See https://github.com/flutter/flutter/issues/95817.
@@ -264,15 +279,17 @@ void PlatformHandlerWin32::SetPlainText(
     const std::string& text,
     std::unique_ptr<MethodResult<rapidjson::Document>> result) {
   ScopedClipboard clipboard;
-  if (!clipboard.Open(std::get<HWND>(*view_->GetRenderTarget()))) {
+  int open_result = clipboard.Open(std::get<HWND>(*view_->GetRenderTarget()));
+  if (open_result != -1) {
     rapidjson::Document error_code;
-    error_code.SetInt(::GetLastError());
+    error_code.SetInt(open_result);
     result->Error(kClipboardError, "Unable to open clipboard", error_code);
     return;
   }
-  if (!clipboard.SetString(fml::Utf8ToWideString(text))) {
+  int set_result = clipboard.SetString(fml::Utf8ToWideString(text));
+  if (set_result != -1) {
     rapidjson::Document error_code;
-    error_code.SetInt(::GetLastError());
+    error_code.SetInt(set_result);
     result->Error(kClipboardError, "Unable to set clipboard data", error_code);
     return;
   }

From fcd81d11fc8f815ddacdddc0f0c02667873bce86 Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Fri, 25 Mar 2022 16:16:03 -0700
Subject: [PATCH 03/16] Can pass in scopedclipboard

---
 .../windows/platform_handler_win32.cc         | 29 ++++++++++---------
 .../platform/windows/platform_handler_win32.h | 17 ++++++++++-
 2 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/shell/platform/windows/platform_handler_win32.cc b/shell/platform/windows/platform_handler_win32.cc
index 7cf245c253f72..95f065c5ccff6 100644
--- a/shell/platform/windows/platform_handler_win32.cc
+++ b/shell/platform/windows/platform_handler_win32.cc
@@ -96,7 +96,7 @@ class ScopedGlobalLock {
 
 // A Clipboard wrapper that automatically closes the clipboard when it goes out
 // of scope.
-class ScopedClipboard {
+class ScopedClipboard : public ScopedClipboardInterface {
  public:
   ScopedClipboard();
   ~ScopedClipboard();
@@ -209,27 +209,32 @@ std::unique_ptr<PlatformHandler> PlatformHandler::Create(
 }
 
 PlatformHandlerWin32::PlatformHandlerWin32(BinaryMessenger* messenger,
-                                           FlutterWindowsView* view)
-    : PlatformHandler(messenger), view_(view) {}
+                                           FlutterWindowsView* view, std::optional<ScopedClipboardInterface*> clipboard_reference = nullptr)
+    : PlatformHandler(messenger), view_(view) {
+      if (clipboard_reference == nullptr) {
+        ScopedClipboard clipboard;
+        clipboard_reference = &clipboard;
+      }
+      clipboard_ = clipboard_reference.value();
+    }
 
 PlatformHandlerWin32::~PlatformHandlerWin32() = default;
 
 void PlatformHandlerWin32::GetPlainText(
     std::unique_ptr<MethodResult<rapidjson::Document>> result,
     std::string_view key) {
-  ScopedClipboard clipboard;
-  int open_result = clipboard.Open(std::get<HWND>(*view_->GetRenderTarget()));
+  int open_result = clipboard_->Open(std::get<HWND>(*view_->GetRenderTarget()));
   if (open_result != -1) {
     rapidjson::Document error_code;
     error_code.SetInt(open_result);
     result->Error(kClipboardError, "Unable to open clipboard", error_code);
     return;
   }
-  if (!clipboard.HasString()) {
+  if (!clipboard_->HasString()) {
     result->Success(rapidjson::Document());
     return;
   }
-  std::variant<std::wstring, int> get_string_result = clipboard.GetString();
+  std::variant<std::wstring, int> get_string_result = clipboard_->GetString();
   if (std::holds_alternative<int>(get_string_result)) {
     rapidjson::Document error_code;
     error_code.SetInt(std::get<int>(get_string_result));
@@ -249,9 +254,8 @@ void PlatformHandlerWin32::GetPlainText(
 
 void PlatformHandlerWin32::GetHasStrings(
     std::unique_ptr<MethodResult<rapidjson::Document>> result) {
-  ScopedClipboard clipboard;
   bool hasStrings;
-  int open_result = clipboard.Open(std::get<HWND>(*view_->GetRenderTarget()));
+  int open_result = clipboard_->Open(std::get<HWND>(*view_->GetRenderTarget()));
   if (open_result != -1) {
     rapidjson::Document error_code;
     error_code.SetInt(open_result);
@@ -264,7 +268,7 @@ void PlatformHandlerWin32::GetHasStrings(
     }
     hasStrings = false;
   } else {
-    hasStrings = clipboard.HasString();
+    hasStrings = clipboard_->HasString();
   }
 
   rapidjson::Document document;
@@ -278,15 +282,14 @@ void PlatformHandlerWin32::GetHasStrings(
 void PlatformHandlerWin32::SetPlainText(
     const std::string& text,
     std::unique_ptr<MethodResult<rapidjson::Document>> result) {
-  ScopedClipboard clipboard;
-  int open_result = clipboard.Open(std::get<HWND>(*view_->GetRenderTarget()));
+  int open_result = clipboard_->Open(std::get<HWND>(*view_->GetRenderTarget()));
   if (open_result != -1) {
     rapidjson::Document error_code;
     error_code.SetInt(open_result);
     result->Error(kClipboardError, "Unable to open clipboard", error_code);
     return;
   }
-  int set_result = clipboard.SetString(fml::Utf8ToWideString(text));
+  int set_result = clipboard_->SetString(fml::Utf8ToWideString(text));
   if (set_result != -1) {
     rapidjson::Document error_code;
     error_code.SetInt(set_result);
diff --git a/shell/platform/windows/platform_handler_win32.h b/shell/platform/windows/platform_handler_win32.h
index d69915d787c39..61101c06868c2 100644
--- a/shell/platform/windows/platform_handler_win32.h
+++ b/shell/platform/windows/platform_handler_win32.h
@@ -15,11 +15,24 @@ namespace flutter {
 
 class FlutterWindowsView;
 
+// A public interface for ScopedClipboard, so that it can be injected into
+// PlatformHandlerWin32.
+class ScopedClipboardInterface {
+ public:
+  virtual int Open(HWND window) = 0;
+
+  virtual bool HasString() = 0;
+
+  virtual std::variant<std::wstring, int> GetString() = 0;
+
+  virtual int SetString(const std::wstring string) = 0;
+};
+
 // Win32 implementation of PlatformHandler.
 class PlatformHandlerWin32 : public PlatformHandler {
  public:
   explicit PlatformHandlerWin32(BinaryMessenger* messenger,
-                                FlutterWindowsView* view);
+                                FlutterWindowsView* view, std::optional<ScopedClipboardInterface*> clipboard_reference);
 
   virtual ~PlatformHandlerWin32();
 
@@ -45,6 +58,8 @@ class PlatformHandlerWin32 : public PlatformHandler {
  private:
   // A reference to the Flutter view.
   FlutterWindowsView* view_;
+  // A clipboard instance that can be passed in.
+  ScopedClipboardInterface* clipboard_;
 };
 
 }  // namespace flutter

From e4f31bab222ea98181095a0158e645935371a58c Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Mon, 28 Mar 2022 16:11:51 -0700
Subject: [PATCH 04/16] Test by injecting a fake ScopedClipboard

---
 shell/platform/windows/BUILD.gn               |   1 +
 .../windows/platform_handler_win32.cc         |  10 +-
 .../platform_handler_win32_unittests.cc       | 124 ++++++++++++++++++
 3 files changed, 127 insertions(+), 8 deletions(-)
 create mode 100644 shell/platform/windows/platform_handler_win32_unittests.cc

diff --git a/shell/platform/windows/BUILD.gn b/shell/platform/windows/BUILD.gn
index 1ac8628583c06..51157138fdd69 100644
--- a/shell/platform/windows/BUILD.gn
+++ b/shell/platform/windows/BUILD.gn
@@ -183,6 +183,7 @@ executable("flutter_windows_unittests") {
     "keyboard_key_handler_unittests.cc",
     "keyboard_win32_unittests.cc",
     "platform_handler_unittests.cc",
+    "platform_handler_win32_unittests.cc",
     "sequential_id_generator_unittests.cc",
     "settings_plugin_unittests.cc",
     "system_utils_unittests.cc",
diff --git a/shell/platform/windows/platform_handler_win32.cc b/shell/platform/windows/platform_handler_win32.cc
index 95f065c5ccff6..2cc936985de10 100644
--- a/shell/platform/windows/platform_handler_win32.cc
+++ b/shell/platform/windows/platform_handler_win32.cc
@@ -141,13 +141,7 @@ int ScopedClipboard::Open(HWND window) {
   opened_ = ::OpenClipboard(window);
 
   if (!opened_) {
-    int error_code = ::GetLastError();
-    // Swallow errors of type ERROR_ACCESS_DENIED. These happen when the app is
-    // not in the foreground and HasStrings is irrelevant.
-    // See https://github.com/flutter/flutter/issues/95817.
-    if (error_code != kAccessDeniedErrorCode) {
-      return error_code;
-    }
+    return ::GetLastError();
   }
 
   return -1;
@@ -260,7 +254,7 @@ void PlatformHandlerWin32::GetHasStrings(
     rapidjson::Document error_code;
     error_code.SetInt(open_result);
     // Swallow errors of type ERROR_ACCESS_DENIED. These happen when the app is
-    // not in the foreground and HasStrings is irrelevant.
+    // not in the foreground and GetHasStrings is irrelevant.
     // See https://github.com/flutter/flutter/issues/95817.
     if (error_code != kAccessDeniedErrorCode) {
       result->Error(kClipboardError, "Unable to open clipboard", error_code);
diff --git a/shell/platform/windows/platform_handler_win32_unittests.cc b/shell/platform/windows/platform_handler_win32_unittests.cc
new file mode 100644
index 0000000000000..cb3382319a7c0
--- /dev/null
+++ b/shell/platform/windows/platform_handler_win32_unittests.cc
@@ -0,0 +1,124 @@
+// Copyright 2013 The Flutter 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 "flutter/shell/platform/windows/platform_handler_win32.h"
+
+#include <memory>
+
+#include "flutter/shell/platform/common/json_method_codec.h"
+#include "flutter/shell/platform/windows/testing/mock_window_binding_handler.h"
+#include "flutter/shell/platform/windows/testing/test_binary_messenger.h"
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "rapidjson/document.h"
+
+namespace flutter {
+namespace testing {
+
+namespace {
+using ::testing::_;
+
+static constexpr char kChannelName[] = "flutter/platform";
+
+static constexpr char kHasStringsClipboardMethod[] = "Clipboard.hasStrings";
+
+static constexpr char kTextPlainFormat[] = "text/plain";
+
+static constexpr char kValueKey[] = "value";
+static constexpr int kAccessDeniedErrorCode = 5;
+
+}  // namespace
+
+// A test version of the private ScopedClipboard.
+class TestScopedClipboard : public ScopedClipboardInterface {
+ public:
+  TestScopedClipboard();
+  ~TestScopedClipboard();
+
+  // Prevent copying.
+  TestScopedClipboard(TestScopedClipboard const&) = delete;
+  TestScopedClipboard& operator=(TestScopedClipboard const&) = delete;
+
+  int Open(HWND window);
+
+  bool HasString();
+
+  std::variant<std::wstring, int> GetString();
+
+  int SetString(const std::wstring string);
+
+ private:
+  bool opened_ = false;
+};
+
+TestScopedClipboard::TestScopedClipboard() {}
+
+TestScopedClipboard::~TestScopedClipboard() {
+  if (opened_) {
+    ::CloseClipboard();
+  }
+}
+
+// Always fail to open with kAccessDeniedErrorCode.
+int TestScopedClipboard::Open(HWND window) {
+  return kAccessDeniedErrorCode;
+}
+
+bool TestScopedClipboard::HasString() {
+  return true;
+}
+
+std::variant<std::wstring, int> TestScopedClipboard::GetString() {
+  return -1;
+}
+
+int TestScopedClipboard::SetString(const std::wstring string) {
+  return -1;
+}
+
+class MockMethodResult : public MethodResult<rapidjson::Document> {
+ public:
+  MOCK_METHOD1(SuccessInternal, void(const rapidjson::Document*));
+  MOCK_METHOD3(ErrorInternal,
+               void(const std::string&,
+                    const std::string&,
+                    const rapidjson::Document*));
+  MOCK_METHOD0(NotImplementedInternal, void());
+};
+
+TEST(PlatformHandlerWin32, HasStringsAccessDeniedReturnsFalseWithoutError) {
+  TestBinaryMessenger messenger;
+  TestScopedClipboard clipboard_reference;
+  FlutterWindowsView view(
+            std::make_unique<::testing::NiceMock<MockWindowBindingHandler>>());
+  PlatformHandlerWin32 platform_handler(&messenger, &view, &clipboard_reference);
+
+  auto args = std::make_unique<rapidjson::Document>(rapidjson::kStringType);
+  auto& allocator = args->GetAllocator();
+  args->SetString(kTextPlainFormat);
+  auto encoded = JsonMethodCodec::GetInstance().EncodeMethodCall(
+      MethodCall<rapidjson::Document>(kHasStringsClipboardMethod,
+                                      std::move(args)));
+
+  MockMethodResult result;
+  rapidjson::Document document;
+  document.SetObject();
+  rapidjson::Document::AllocatorType& document_allocator = document.GetAllocator();
+  document.AddMember(rapidjson::Value(kValueKey, document_allocator),
+                     rapidjson::Value(false), document_allocator);
+
+  EXPECT_CALL(result, SuccessInternal(_))
+      .WillOnce([](const rapidjson::Document* document) {
+        ASSERT_FALSE((*document)[kValueKey].GetBool());
+      });
+  EXPECT_TRUE(messenger.SimulateEngineMessage(
+      kChannelName, encoded->data(), encoded->size(),
+      [&](const uint8_t* reply, size_t reply_size) {
+        JsonMethodCodec::GetInstance().DecodeAndProcessResponseEnvelope(
+            reply, reply_size, &result);
+      }));
+}
+
+}  // namespace testing
+}  // namespace flutter

From e97172e96488f50a7b19cbbd77bab1679b7d7421 Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Tue, 29 Mar 2022 14:30:22 -0700
Subject: [PATCH 05/16] Formatting

---
 .../windows/platform_handler_win32.cc         | 22 +++++++++++--------
 .../platform/windows/platform_handler_win32.h |  6 +++--
 .../platform_handler_win32_unittests.cc       |  8 ++++---
 3 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/shell/platform/windows/platform_handler_win32.cc b/shell/platform/windows/platform_handler_win32.cc
index 2cc936985de10..9c0a2e7bedbbc 100644
--- a/shell/platform/windows/platform_handler_win32.cc
+++ b/shell/platform/windows/platform_handler_win32.cc
@@ -202,15 +202,17 @@ std::unique_ptr<PlatformHandler> PlatformHandler::Create(
   return std::make_unique<PlatformHandlerWin32>(messenger, view);
 }
 
-PlatformHandlerWin32::PlatformHandlerWin32(BinaryMessenger* messenger,
-                                           FlutterWindowsView* view, std::optional<ScopedClipboardInterface*> clipboard_reference = nullptr)
+PlatformHandlerWin32::PlatformHandlerWin32(
+    BinaryMessenger* messenger,
+    FlutterWindowsView* view,
+    std::optional<ScopedClipboardInterface*> clipboard_reference = nullptr)
     : PlatformHandler(messenger), view_(view) {
-      if (clipboard_reference == nullptr) {
-        ScopedClipboard clipboard;
-        clipboard_reference = &clipboard;
-      }
-      clipboard_ = clipboard_reference.value();
-    }
+  if (clipboard_reference == nullptr) {
+    ScopedClipboard clipboard;
+    clipboard_reference = &clipboard;
+  }
+  clipboard_ = clipboard_reference.value();
+}
 
 PlatformHandlerWin32::~PlatformHandlerWin32() = default;
 
@@ -241,7 +243,9 @@ void PlatformHandlerWin32::GetPlainText(
   rapidjson::Document::AllocatorType& allocator = document.GetAllocator();
   document.AddMember(
       rapidjson::Value(key.data(), allocator),
-      rapidjson::Value(fml::WideStringToUtf8(std::get<std::wstring>(get_string_result)), allocator),
+      rapidjson::Value(
+          fml::WideStringToUtf8(std::get<std::wstring>(get_string_result)),
+          allocator),
       allocator);
   result->Success(document);
 }
diff --git a/shell/platform/windows/platform_handler_win32.h b/shell/platform/windows/platform_handler_win32.h
index 61101c06868c2..f5a758a4d79a9 100644
--- a/shell/platform/windows/platform_handler_win32.h
+++ b/shell/platform/windows/platform_handler_win32.h
@@ -31,8 +31,10 @@ class ScopedClipboardInterface {
 // Win32 implementation of PlatformHandler.
 class PlatformHandlerWin32 : public PlatformHandler {
  public:
-  explicit PlatformHandlerWin32(BinaryMessenger* messenger,
-                                FlutterWindowsView* view, std::optional<ScopedClipboardInterface*> clipboard_reference);
+  explicit PlatformHandlerWin32(
+      BinaryMessenger* messenger,
+      FlutterWindowsView* view,
+      std::optional<ScopedClipboardInterface*> clipboard_reference);
 
   virtual ~PlatformHandlerWin32();
 
diff --git a/shell/platform/windows/platform_handler_win32_unittests.cc b/shell/platform/windows/platform_handler_win32_unittests.cc
index cb3382319a7c0..84c8b77cb6065 100644
--- a/shell/platform/windows/platform_handler_win32_unittests.cc
+++ b/shell/platform/windows/platform_handler_win32_unittests.cc
@@ -91,8 +91,9 @@ TEST(PlatformHandlerWin32, HasStringsAccessDeniedReturnsFalseWithoutError) {
   TestBinaryMessenger messenger;
   TestScopedClipboard clipboard_reference;
   FlutterWindowsView view(
-            std::make_unique<::testing::NiceMock<MockWindowBindingHandler>>());
-  PlatformHandlerWin32 platform_handler(&messenger, &view, &clipboard_reference);
+      std::make_unique<::testing::NiceMock<MockWindowBindingHandler>>());
+  PlatformHandlerWin32 platform_handler(&messenger, &view,
+                                        &clipboard_reference);
 
   auto args = std::make_unique<rapidjson::Document>(rapidjson::kStringType);
   auto& allocator = args->GetAllocator();
@@ -104,7 +105,8 @@ TEST(PlatformHandlerWin32, HasStringsAccessDeniedReturnsFalseWithoutError) {
   MockMethodResult result;
   rapidjson::Document document;
   document.SetObject();
-  rapidjson::Document::AllocatorType& document_allocator = document.GetAllocator();
+  rapidjson::Document::AllocatorType& document_allocator =
+      document.GetAllocator();
   document.AddMember(rapidjson::Value(kValueKey, document_allocator),
                      rapidjson::Value(false), document_allocator);
 

From 1b764e6144fcaa44f765f0549394131cf57b658b Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Tue, 29 Mar 2022 15:19:13 -0700
Subject: [PATCH 06/16] License

---
 ci/licenses_golden/licenses_flutter | 1 +
 1 file changed, 1 insertion(+)

diff --git a/ci/licenses_golden/licenses_flutter b/ci/licenses_golden/licenses_flutter
index cc529b958e279..77997513f80b8 100644
--- a/ci/licenses_golden/licenses_flutter
+++ b/ci/licenses_golden/licenses_flutter
@@ -2271,6 +2271,7 @@ FILE: ../../../flutter/shell/platform/windows/platform_handler.h
 FILE: ../../../flutter/shell/platform/windows/platform_handler_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/platform_handler_win32.cc
 FILE: ../../../flutter/shell/platform/windows/platform_handler_win32.h
+FILE: ../../../flutter/shell/platform/windows/platform_handler_win32_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/public/flutter_windows.h
 FILE: ../../../flutter/shell/platform/windows/sequential_id_generator.cc
 FILE: ../../../flutter/shell/platform/windows/sequential_id_generator.h

From 173da5d8e97a5952315258eaf90b867304205b89 Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Fri, 8 Apr 2022 12:34:38 -0700
Subject: [PATCH 07/16] Code review: 0 success error code

---
 .../platform/windows/platform_handler_win32.cc  | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/shell/platform/windows/platform_handler_win32.cc b/shell/platform/windows/platform_handler_win32.cc
index 9c0a2e7bedbbc..ebcf4ec093830 100644
--- a/shell/platform/windows/platform_handler_win32.cc
+++ b/shell/platform/windows/platform_handler_win32.cc
@@ -15,6 +15,7 @@
 
 static constexpr char kValueKey[] = "value";
 static constexpr int kAccessDeniedErrorCode = 5;
+static constexpr int kErrorSuccess = 0;
 
 namespace flutter {
 
@@ -106,7 +107,7 @@ class ScopedClipboard : public ScopedClipboardInterface {
   ScopedClipboard& operator=(ScopedClipboard const&) = delete;
 
   // Attempts to open the clipboard for the given window, returning the error
-  // code in the case of failure and -1 otherwise.
+  // code in the case of failure and 0 otherwise.
   int Open(HWND window);
 
   // Returns true if there is string data available to get.
@@ -120,7 +121,7 @@ class ScopedClipboard : public ScopedClipboardInterface {
   std::variant<std::wstring, int> GetString();
 
   // Sets the string content of the clipboard, returning the error code on
-  // failure and -1 otherwise.
+  // failure and 0 otherwise.
   //
   // Open(...) must have succeeded to call this method.
   int SetString(const std::wstring string);
@@ -144,7 +145,7 @@ int ScopedClipboard::Open(HWND window) {
     return ::GetLastError();
   }
 
-  return -1;
+  return kErrorSuccess;
 }
 
 bool ScopedClipboard::HasString() {
@@ -190,7 +191,7 @@ int ScopedClipboard::SetString(const std::wstring string) {
   }
   // The clipboard now owns the global memory.
   destination_memory.release();
-  return -1;
+  return kErrorSuccess;
 }
 
 }  // namespace
@@ -220,7 +221,7 @@ void PlatformHandlerWin32::GetPlainText(
     std::unique_ptr<MethodResult<rapidjson::Document>> result,
     std::string_view key) {
   int open_result = clipboard_->Open(std::get<HWND>(*view_->GetRenderTarget()));
-  if (open_result != -1) {
+  if (open_result != kErrorSuccess) {
     rapidjson::Document error_code;
     error_code.SetInt(open_result);
     result->Error(kClipboardError, "Unable to open clipboard", error_code);
@@ -254,7 +255,7 @@ void PlatformHandlerWin32::GetHasStrings(
     std::unique_ptr<MethodResult<rapidjson::Document>> result) {
   bool hasStrings;
   int open_result = clipboard_->Open(std::get<HWND>(*view_->GetRenderTarget()));
-  if (open_result != -1) {
+  if (open_result != kErrorSuccess) {
     rapidjson::Document error_code;
     error_code.SetInt(open_result);
     // Swallow errors of type ERROR_ACCESS_DENIED. These happen when the app is
@@ -281,14 +282,14 @@ void PlatformHandlerWin32::SetPlainText(
     const std::string& text,
     std::unique_ptr<MethodResult<rapidjson::Document>> result) {
   int open_result = clipboard_->Open(std::get<HWND>(*view_->GetRenderTarget()));
-  if (open_result != -1) {
+  if (open_result != kErrorSuccess) {
     rapidjson::Document error_code;
     error_code.SetInt(open_result);
     result->Error(kClipboardError, "Unable to open clipboard", error_code);
     return;
   }
   int set_result = clipboard_->SetString(fml::Utf8ToWideString(text));
-  if (set_result != -1) {
+  if (set_result != kErrorSuccess) {
     rapidjson::Document error_code;
     error_code.SetInt(set_result);
     result->Error(kClipboardError, "Unable to set clipboard data", error_code);

From 519bc4fd767a52efea32376155ddd23e83236d7d Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Fri, 8 Apr 2022 13:49:39 -0700
Subject: [PATCH 08/16] Code review redundant GetStrings

---
 shell/platform/windows/platform_handler_win32.cc | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/shell/platform/windows/platform_handler_win32.cc b/shell/platform/windows/platform_handler_win32.cc
index ebcf4ec093830..a2a25cc4aac8e 100644
--- a/shell/platform/windows/platform_handler_win32.cc
+++ b/shell/platform/windows/platform_handler_win32.cc
@@ -162,9 +162,6 @@ std::variant<std::wstring, int> ScopedClipboard::GetString() {
     return ::GetLastError();
   }
   ScopedGlobalLock locked_data(data);
-  if (!locked_data.get()) {
-    return ::GetLastError();
-  }
   std::optional<std::wstring> string = static_cast<wchar_t*>(locked_data.get());
   if (!string) {
     return ::GetLastError();

From 047bad154cb656af82b390775da610bb62349518 Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Fri, 8 Apr 2022 15:16:21 -0700
Subject: [PATCH 09/16] Code review:virtual destructor and moved comments to
 header and overrides

---
 shell/platform/windows/platform_handler_win32.cc | 14 +-------------
 shell/platform/windows/platform_handler_win32.h  | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/shell/platform/windows/platform_handler_win32.cc b/shell/platform/windows/platform_handler_win32.cc
index a2a25cc4aac8e..d69fae722f0ca 100644
--- a/shell/platform/windows/platform_handler_win32.cc
+++ b/shell/platform/windows/platform_handler_win32.cc
@@ -100,30 +100,18 @@ class ScopedGlobalLock {
 class ScopedClipboard : public ScopedClipboardInterface {
  public:
   ScopedClipboard();
-  ~ScopedClipboard();
+  virtual ~ScopedClipboard();
 
   // Prevent copying.
   ScopedClipboard(ScopedClipboard const&) = delete;
   ScopedClipboard& operator=(ScopedClipboard const&) = delete;
 
-  // Attempts to open the clipboard for the given window, returning the error
-  // code in the case of failure and 0 otherwise.
   int Open(HWND window);
 
-  // Returns true if there is string data available to get.
   bool HasString();
 
-  // Returns string data from the clipboard.
-  //
-  // If getting a string fails, returns the error code.
-  //
-  // Open(...) must have succeeded to call this method.
   std::variant<std::wstring, int> GetString();
 
-  // Sets the string content of the clipboard, returning the error code on
-  // failure and 0 otherwise.
-  //
-  // Open(...) must have succeeded to call this method.
   int SetString(const std::wstring string);
 
  private:
diff --git a/shell/platform/windows/platform_handler_win32.h b/shell/platform/windows/platform_handler_win32.h
index f5a758a4d79a9..8a7c684ba6fb9 100644
--- a/shell/platform/windows/platform_handler_win32.h
+++ b/shell/platform/windows/platform_handler_win32.h
@@ -19,12 +19,26 @@ class FlutterWindowsView;
 // PlatformHandlerWin32.
 class ScopedClipboardInterface {
  public:
+  virtual ~ScopedClipboardInterface() {};
+
+  // Attempts to open the clipboard for the given window, returning the error
+  // code in the case of failure and 0 otherwise.
   virtual int Open(HWND window) = 0;
 
+  // Returns true if there is string data available to get.
   virtual bool HasString() = 0;
 
+  // Returns string data from the clipboard.
+  //
+  // If getting a string fails, returns the error code.
+  //
+  // Open(...) must have succeeded to call this method.
   virtual std::variant<std::wstring, int> GetString() = 0;
 
+  // Sets the string content of the clipboard, returning the error code on
+  // failure and 0 otherwise.
+  //
+  // Open(...) must have succeeded to call this method.
   virtual int SetString(const std::wstring string) = 0;
 };
 

From 479b568a356321867a2ae55e0c17e44053c2bfe5 Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Fri, 8 Apr 2022 15:30:28 -0700
Subject: [PATCH 10/16] Code review:overrides and clipboard_reference naming
 and remove optional

---
 .../platform/windows/platform_handler_win32.cc | 18 +++++++++---------
 .../platform/windows/platform_handler_win32.h  |  2 +-
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/shell/platform/windows/platform_handler_win32.cc b/shell/platform/windows/platform_handler_win32.cc
index d69fae722f0ca..1838091768297 100644
--- a/shell/platform/windows/platform_handler_win32.cc
+++ b/shell/platform/windows/platform_handler_win32.cc
@@ -106,13 +106,13 @@ class ScopedClipboard : public ScopedClipboardInterface {
   ScopedClipboard(ScopedClipboard const&) = delete;
   ScopedClipboard& operator=(ScopedClipboard const&) = delete;
 
-  int Open(HWND window);
+  int Open(HWND window) override;
 
-  bool HasString();
+  bool HasString() override;
 
-  std::variant<std::wstring, int> GetString();
+  std::variant<std::wstring, int> GetString() override;
 
-  int SetString(const std::wstring string);
+  int SetString(const std::wstring string) override;
 
  private:
   bool opened_ = false;
@@ -191,13 +191,13 @@ std::unique_ptr<PlatformHandler> PlatformHandler::Create(
 PlatformHandlerWin32::PlatformHandlerWin32(
     BinaryMessenger* messenger,
     FlutterWindowsView* view,
-    std::optional<ScopedClipboardInterface*> clipboard_reference = nullptr)
+    ScopedClipboardInterface* clipboard = nullptr)
     : PlatformHandler(messenger), view_(view) {
-  if (clipboard_reference == nullptr) {
-    ScopedClipboard clipboard;
-    clipboard_reference = &clipboard;
+  if (clipboard == nullptr) {
+    ScopedClipboard scoped_clipboard;
+    clipboard = &scoped_clipboard;
   }
-  clipboard_ = clipboard_reference.value();
+  clipboard_ = clipboard;
 }
 
 PlatformHandlerWin32::~PlatformHandlerWin32() = default;
diff --git a/shell/platform/windows/platform_handler_win32.h b/shell/platform/windows/platform_handler_win32.h
index 8a7c684ba6fb9..c9055c437f436 100644
--- a/shell/platform/windows/platform_handler_win32.h
+++ b/shell/platform/windows/platform_handler_win32.h
@@ -48,7 +48,7 @@ class PlatformHandlerWin32 : public PlatformHandler {
   explicit PlatformHandlerWin32(
       BinaryMessenger* messenger,
       FlutterWindowsView* view,
-      std::optional<ScopedClipboardInterface*> clipboard_reference);
+      ScopedClipboardInterface* clipboard);
 
   virtual ~PlatformHandlerWin32();
 

From 437ab103f82bf14a6ffabbdac5bf03e60efcb13b Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Fri, 8 Apr 2022 15:34:03 -0700
Subject: [PATCH 11/16] Code review:clipboard default parameter

---
 shell/platform/windows/platform_handler_win32.cc | 2 +-
 shell/platform/windows/platform_handler_win32.h  | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/shell/platform/windows/platform_handler_win32.cc b/shell/platform/windows/platform_handler_win32.cc
index 1838091768297..226f0c136c264 100644
--- a/shell/platform/windows/platform_handler_win32.cc
+++ b/shell/platform/windows/platform_handler_win32.cc
@@ -191,7 +191,7 @@ std::unique_ptr<PlatformHandler> PlatformHandler::Create(
 PlatformHandlerWin32::PlatformHandlerWin32(
     BinaryMessenger* messenger,
     FlutterWindowsView* view,
-    ScopedClipboardInterface* clipboard = nullptr)
+    ScopedClipboardInterface* clipboard)
     : PlatformHandler(messenger), view_(view) {
   if (clipboard == nullptr) {
     ScopedClipboard scoped_clipboard;
diff --git a/shell/platform/windows/platform_handler_win32.h b/shell/platform/windows/platform_handler_win32.h
index c9055c437f436..d68bf195f7ff0 100644
--- a/shell/platform/windows/platform_handler_win32.h
+++ b/shell/platform/windows/platform_handler_win32.h
@@ -48,7 +48,7 @@ class PlatformHandlerWin32 : public PlatformHandler {
   explicit PlatformHandlerWin32(
       BinaryMessenger* messenger,
       FlutterWindowsView* view,
-      ScopedClipboardInterface* clipboard);
+      ScopedClipboardInterface* clipboard = nullptr);
 
   virtual ~PlatformHandlerWin32();
 
@@ -74,7 +74,7 @@ class PlatformHandlerWin32 : public PlatformHandler {
  private:
   // A reference to the Flutter view.
   FlutterWindowsView* view_;
-  // A clipboard instance that can be passed in.
+  // A clipboard instance that can be passed in for mocking in tests.
   ScopedClipboardInterface* clipboard_;
 };
 

From dd97459ebdd0264f6a0dda4d9c91e24e353c0898 Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Mon, 11 Apr 2022 15:30:03 -0700
Subject: [PATCH 12/16] Code review: unique_ptr

---
 shell/platform/windows/platform_handler_win32.cc          | 8 ++++----
 shell/platform/windows/platform_handler_win32.h           | 4 ++--
 .../platform/windows/platform_handler_win32_unittests.cc  | 3 +--
 3 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/shell/platform/windows/platform_handler_win32.cc b/shell/platform/windows/platform_handler_win32.cc
index 226f0c136c264..038f269fbbde1 100644
--- a/shell/platform/windows/platform_handler_win32.cc
+++ b/shell/platform/windows/platform_handler_win32.cc
@@ -191,13 +191,13 @@ std::unique_ptr<PlatformHandler> PlatformHandler::Create(
 PlatformHandlerWin32::PlatformHandlerWin32(
     BinaryMessenger* messenger,
     FlutterWindowsView* view,
-    ScopedClipboardInterface* clipboard)
+    std::unique_ptr<ScopedClipboardInterface> clipboard)
     : PlatformHandler(messenger), view_(view) {
   if (clipboard == nullptr) {
-    ScopedClipboard scoped_clipboard;
-    clipboard = &scoped_clipboard;
+    clipboard_ = std::make_unique<ScopedClipboard>();
+  } else {
+    clipboard_ = std::move(clipboard);
   }
-  clipboard_ = clipboard;
 }
 
 PlatformHandlerWin32::~PlatformHandlerWin32() = default;
diff --git a/shell/platform/windows/platform_handler_win32.h b/shell/platform/windows/platform_handler_win32.h
index d68bf195f7ff0..e9771c7565fbe 100644
--- a/shell/platform/windows/platform_handler_win32.h
+++ b/shell/platform/windows/platform_handler_win32.h
@@ -48,7 +48,7 @@ class PlatformHandlerWin32 : public PlatformHandler {
   explicit PlatformHandlerWin32(
       BinaryMessenger* messenger,
       FlutterWindowsView* view,
-      ScopedClipboardInterface* clipboard = nullptr);
+      std::unique_ptr<ScopedClipboardInterface> clipboard = nullptr);
 
   virtual ~PlatformHandlerWin32();
 
@@ -75,7 +75,7 @@ class PlatformHandlerWin32 : public PlatformHandler {
   // A reference to the Flutter view.
   FlutterWindowsView* view_;
   // A clipboard instance that can be passed in for mocking in tests.
-  ScopedClipboardInterface* clipboard_;
+  std::unique_ptr<ScopedClipboardInterface> clipboard_;
 };
 
 }  // namespace flutter
diff --git a/shell/platform/windows/platform_handler_win32_unittests.cc b/shell/platform/windows/platform_handler_win32_unittests.cc
index 84c8b77cb6065..fc910b4fc9d9a 100644
--- a/shell/platform/windows/platform_handler_win32_unittests.cc
+++ b/shell/platform/windows/platform_handler_win32_unittests.cc
@@ -89,11 +89,10 @@ class MockMethodResult : public MethodResult<rapidjson::Document> {
 
 TEST(PlatformHandlerWin32, HasStringsAccessDeniedReturnsFalseWithoutError) {
   TestBinaryMessenger messenger;
-  TestScopedClipboard clipboard_reference;
   FlutterWindowsView view(
       std::make_unique<::testing::NiceMock<MockWindowBindingHandler>>());
   PlatformHandlerWin32 platform_handler(&messenger, &view,
-                                        &clipboard_reference);
+                                        std::make_unique<TestScopedClipboard>());
 
   auto args = std::make_unique<rapidjson::Document>(rapidjson::kStringType);
   auto& allocator = args->GetAllocator();

From 33a98e37ac6f9804f5644d2a844ab20077bf580a Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Tue, 12 Apr 2022 09:47:31 -0700
Subject: [PATCH 13/16] Code review: Full tests for hasstrings

---
 .../platform/windows/platform_handler_win32.h |   2 +-
 .../platform_handler_win32_unittests.cc       | 364 ++++++++++++------
 2 files changed, 240 insertions(+), 126 deletions(-)

diff --git a/shell/platform/windows/platform_handler_win32.h b/shell/platform/windows/platform_handler_win32.h
index e9771c7565fbe..62d6444158462 100644
--- a/shell/platform/windows/platform_handler_win32.h
+++ b/shell/platform/windows/platform_handler_win32.h
@@ -19,7 +19,7 @@ class FlutterWindowsView;
 // PlatformHandlerWin32.
 class ScopedClipboardInterface {
  public:
-  virtual ~ScopedClipboardInterface() {};
+  virtual ~ScopedClipboardInterface(){};
 
   // Attempts to open the clipboard for the given window, returning the error
   // code in the case of failure and 0 otherwise.
diff --git a/shell/platform/windows/platform_handler_win32_unittests.cc b/shell/platform/windows/platform_handler_win32_unittests.cc
index fc910b4fc9d9a..be503014f36f6 100644
--- a/shell/platform/windows/platform_handler_win32_unittests.cc
+++ b/shell/platform/windows/platform_handler_win32_unittests.cc
@@ -1,125 +1,239 @@
-// Copyright 2013 The Flutter 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 "flutter/shell/platform/windows/platform_handler_win32.h"
-
-#include <memory>
-
-#include "flutter/shell/platform/common/json_method_codec.h"
-#include "flutter/shell/platform/windows/testing/mock_window_binding_handler.h"
-#include "flutter/shell/platform/windows/testing/test_binary_messenger.h"
-#include "gmock/gmock.h"
-#include "gtest/gtest.h"
-#include "rapidjson/document.h"
-
-namespace flutter {
-namespace testing {
-
-namespace {
-using ::testing::_;
-
-static constexpr char kChannelName[] = "flutter/platform";
-
-static constexpr char kHasStringsClipboardMethod[] = "Clipboard.hasStrings";
-
-static constexpr char kTextPlainFormat[] = "text/plain";
-
-static constexpr char kValueKey[] = "value";
-static constexpr int kAccessDeniedErrorCode = 5;
-
-}  // namespace
-
-// A test version of the private ScopedClipboard.
-class TestScopedClipboard : public ScopedClipboardInterface {
- public:
-  TestScopedClipboard();
-  ~TestScopedClipboard();
-
-  // Prevent copying.
-  TestScopedClipboard(TestScopedClipboard const&) = delete;
-  TestScopedClipboard& operator=(TestScopedClipboard const&) = delete;
-
-  int Open(HWND window);
-
-  bool HasString();
-
-  std::variant<std::wstring, int> GetString();
-
-  int SetString(const std::wstring string);
-
- private:
-  bool opened_ = false;
-};
-
-TestScopedClipboard::TestScopedClipboard() {}
-
-TestScopedClipboard::~TestScopedClipboard() {
-  if (opened_) {
-    ::CloseClipboard();
-  }
-}
-
-// Always fail to open with kAccessDeniedErrorCode.
-int TestScopedClipboard::Open(HWND window) {
-  return kAccessDeniedErrorCode;
-}
-
-bool TestScopedClipboard::HasString() {
-  return true;
-}
-
-std::variant<std::wstring, int> TestScopedClipboard::GetString() {
-  return -1;
-}
-
-int TestScopedClipboard::SetString(const std::wstring string) {
-  return -1;
-}
-
-class MockMethodResult : public MethodResult<rapidjson::Document> {
- public:
-  MOCK_METHOD1(SuccessInternal, void(const rapidjson::Document*));
-  MOCK_METHOD3(ErrorInternal,
-               void(const std::string&,
-                    const std::string&,
-                    const rapidjson::Document*));
-  MOCK_METHOD0(NotImplementedInternal, void());
-};
-
-TEST(PlatformHandlerWin32, HasStringsAccessDeniedReturnsFalseWithoutError) {
-  TestBinaryMessenger messenger;
-  FlutterWindowsView view(
-      std::make_unique<::testing::NiceMock<MockWindowBindingHandler>>());
-  PlatformHandlerWin32 platform_handler(&messenger, &view,
-                                        std::make_unique<TestScopedClipboard>());
-
-  auto args = std::make_unique<rapidjson::Document>(rapidjson::kStringType);
-  auto& allocator = args->GetAllocator();
-  args->SetString(kTextPlainFormat);
-  auto encoded = JsonMethodCodec::GetInstance().EncodeMethodCall(
-      MethodCall<rapidjson::Document>(kHasStringsClipboardMethod,
-                                      std::move(args)));
-
-  MockMethodResult result;
-  rapidjson::Document document;
-  document.SetObject();
-  rapidjson::Document::AllocatorType& document_allocator =
-      document.GetAllocator();
-  document.AddMember(rapidjson::Value(kValueKey, document_allocator),
-                     rapidjson::Value(false), document_allocator);
-
-  EXPECT_CALL(result, SuccessInternal(_))
-      .WillOnce([](const rapidjson::Document* document) {
-        ASSERT_FALSE((*document)[kValueKey].GetBool());
-      });
-  EXPECT_TRUE(messenger.SimulateEngineMessage(
-      kChannelName, encoded->data(), encoded->size(),
-      [&](const uint8_t* reply, size_t reply_size) {
-        JsonMethodCodec::GetInstance().DecodeAndProcessResponseEnvelope(
-            reply, reply_size, &result);
-      }));
-}
-
-}  // namespace testing
-}  // namespace flutter
+// Copyright 2013 The Flutter 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 "flutter/shell/platform/windows/platform_handler_win32.h"
+
+#include <memory>
+
+#include "flutter/shell/platform/common/json_method_codec.h"
+#include "flutter/shell/platform/windows/testing/mock_window_binding_handler.h"
+#include "flutter/shell/platform/windows/testing/test_binary_messenger.h"
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "rapidjson/document.h"
+
+namespace flutter {
+namespace testing {
+
+namespace {
+using ::testing::_;
+
+static constexpr char kChannelName[] = "flutter/platform";
+
+static constexpr char kHasStringsClipboardMethod[] = "Clipboard.hasStrings";
+
+static constexpr char kTextPlainFormat[] = "text/plain";
+
+static constexpr char kValueKey[] = "value";
+static constexpr int kAccessDeniedErrorCode = 5;
+static constexpr int kErrorSuccess = 0;
+
+}  // namespace
+
+// A test version of the private ScopedClipboard.
+class TestScopedClipboard : public ScopedClipboardInterface {
+ public:
+  TestScopedClipboard(int open_error, bool has_strings);
+  ~TestScopedClipboard();
+
+  // Prevent copying.
+  TestScopedClipboard(TestScopedClipboard const&) = delete;
+  TestScopedClipboard& operator=(TestScopedClipboard const&) = delete;
+
+  int Open(HWND window);
+
+  bool HasString();
+
+  std::variant<std::wstring, int> GetString();
+
+  int SetString(const std::wstring string);
+
+ private:
+  bool opened_ = false;
+  bool has_strings_;
+  int open_error_;
+};
+
+TestScopedClipboard::TestScopedClipboard(int open_error, bool has_strings) {
+  open_error_ = open_error;
+  has_strings_ = has_strings;
+};
+
+TestScopedClipboard::~TestScopedClipboard() {
+  if (opened_) {
+    ::CloseClipboard();
+  }
+}
+
+int TestScopedClipboard::Open(HWND window) {
+  return open_error_;
+}
+
+bool TestScopedClipboard::HasString() {
+  return has_strings_;
+}
+
+std::variant<std::wstring, int> TestScopedClipboard::GetString() {
+  return -1;
+}
+
+int TestScopedClipboard::SetString(const std::wstring string) {
+  return -1;
+}
+
+class MockMethodResult : public MethodResult<rapidjson::Document> {
+ public:
+  MOCK_METHOD1(SuccessInternal, void(const rapidjson::Document*));
+  MOCK_METHOD3(ErrorInternal,
+               void(const std::string&,
+                    const std::string&,
+                    const rapidjson::Document*));
+  MOCK_METHOD0(NotImplementedInternal, void());
+};
+
+// Regression test for https://github.com/flutter/flutter/issues/95817.
+TEST(PlatformHandlerWin32, HasStringsAccessDeniedReturnsFalseWithoutError) {
+  TestBinaryMessenger messenger;
+  FlutterWindowsView view(
+      std::make_unique<::testing::NiceMock<MockWindowBindingHandler>>());
+  // HasStrings will receive access denied on the clipboard, but will return
+  // false without error.
+  PlatformHandlerWin32 platform_handler(
+      &messenger, &view,
+      std::make_unique<TestScopedClipboard>(kAccessDeniedErrorCode, true));
+
+  auto args = std::make_unique<rapidjson::Document>(rapidjson::kStringType);
+  auto& allocator = args->GetAllocator();
+  args->SetString(kTextPlainFormat);
+  auto encoded = JsonMethodCodec::GetInstance().EncodeMethodCall(
+      MethodCall<rapidjson::Document>(kHasStringsClipboardMethod,
+                                      std::move(args)));
+
+  MockMethodResult result;
+  rapidjson::Document document;
+  document.SetObject();
+  rapidjson::Document::AllocatorType& document_allocator =
+      document.GetAllocator();
+  document.AddMember(rapidjson::Value(kValueKey, document_allocator),
+                     rapidjson::Value(false), document_allocator);
+
+  EXPECT_CALL(result, SuccessInternal(_))
+      .WillOnce([](const rapidjson::Document* document) {
+        ASSERT_FALSE((*document)[kValueKey].GetBool());
+      });
+  EXPECT_TRUE(messenger.SimulateEngineMessage(
+      kChannelName, encoded->data(), encoded->size(),
+      [&](const uint8_t* reply, size_t reply_size) {
+        JsonMethodCodec::GetInstance().DecodeAndProcessResponseEnvelope(
+            reply, reply_size, &result);
+      }));
+}
+
+TEST(PlatformHandlerWin32, HasStringsSuccessWithStrings) {
+  TestBinaryMessenger messenger;
+  FlutterWindowsView view(
+      std::make_unique<::testing::NiceMock<MockWindowBindingHandler>>());
+  // HasStrings will succeed and return true.
+  PlatformHandlerWin32 platform_handler(
+      &messenger, &view,
+      std::make_unique<TestScopedClipboard>(kErrorSuccess, true));
+
+  auto args = std::make_unique<rapidjson::Document>(rapidjson::kStringType);
+  auto& allocator = args->GetAllocator();
+  args->SetString(kTextPlainFormat);
+  auto encoded = JsonMethodCodec::GetInstance().EncodeMethodCall(
+      MethodCall<rapidjson::Document>(kHasStringsClipboardMethod,
+                                      std::move(args)));
+
+  MockMethodResult result;
+  rapidjson::Document document;
+  document.SetObject();
+  rapidjson::Document::AllocatorType& document_allocator =
+      document.GetAllocator();
+  document.AddMember(rapidjson::Value(kValueKey, document_allocator),
+                     rapidjson::Value(false), document_allocator);
+
+  EXPECT_CALL(result, SuccessInternal(_))
+      .WillOnce([](const rapidjson::Document* document) {
+        ASSERT_TRUE((*document)[kValueKey].GetBool());
+      });
+  EXPECT_TRUE(messenger.SimulateEngineMessage(
+      kChannelName, encoded->data(), encoded->size(),
+      [&](const uint8_t* reply, size_t reply_size) {
+        JsonMethodCodec::GetInstance().DecodeAndProcessResponseEnvelope(
+            reply, reply_size, &result);
+      }));
+}
+
+TEST(PlatformHandlerWin32, HasStringsSuccessWithoutStrings) {
+  TestBinaryMessenger messenger;
+  FlutterWindowsView view(
+      std::make_unique<::testing::NiceMock<MockWindowBindingHandler>>());
+  // HasStrings will succeed and return false.
+  PlatformHandlerWin32 platform_handler(
+      &messenger, &view,
+      std::make_unique<TestScopedClipboard>(kErrorSuccess, false));
+
+  auto args = std::make_unique<rapidjson::Document>(rapidjson::kStringType);
+  auto& allocator = args->GetAllocator();
+  args->SetString(kTextPlainFormat);
+  auto encoded = JsonMethodCodec::GetInstance().EncodeMethodCall(
+      MethodCall<rapidjson::Document>(kHasStringsClipboardMethod,
+                                      std::move(args)));
+
+  MockMethodResult result;
+  rapidjson::Document document;
+  document.SetObject();
+  rapidjson::Document::AllocatorType& document_allocator =
+      document.GetAllocator();
+  document.AddMember(rapidjson::Value(kValueKey, document_allocator),
+                     rapidjson::Value(false), document_allocator);
+
+  EXPECT_CALL(result, SuccessInternal(_))
+      .WillOnce([](const rapidjson::Document* document) {
+        ASSERT_FALSE((*document)[kValueKey].GetBool());
+      });
+  EXPECT_TRUE(messenger.SimulateEngineMessage(
+      kChannelName, encoded->data(), encoded->size(),
+      [&](const uint8_t* reply, size_t reply_size) {
+        JsonMethodCodec::GetInstance().DecodeAndProcessResponseEnvelope(
+            reply, reply_size, &result);
+      }));
+}
+
+TEST(PlatformHandlerWin32, HasStringsError) {
+  TestBinaryMessenger messenger;
+  FlutterWindowsView view(
+      std::make_unique<::testing::NiceMock<MockWindowBindingHandler>>());
+  // HasStrings will fail.
+  PlatformHandlerWin32 platform_handler(
+      &messenger, &view, std::make_unique<TestScopedClipboard>(1, true));
+
+  auto args = std::make_unique<rapidjson::Document>(rapidjson::kStringType);
+  auto& allocator = args->GetAllocator();
+  args->SetString(kTextPlainFormat);
+  auto encoded = JsonMethodCodec::GetInstance().EncodeMethodCall(
+      MethodCall<rapidjson::Document>(kHasStringsClipboardMethod,
+                                      std::move(args)));
+
+  MockMethodResult result;
+  rapidjson::Document document;
+  document.SetObject();
+  rapidjson::Document::AllocatorType& document_allocator =
+      document.GetAllocator();
+  document.AddMember(rapidjson::Value(kValueKey, document_allocator),
+                     rapidjson::Value(false), document_allocator);
+
+  EXPECT_CALL(result, SuccessInternal(_)).Times(0);
+  EXPECT_CALL(result, ErrorInternal(_, _, _)).Times(1);
+  EXPECT_TRUE(messenger.SimulateEngineMessage(
+      kChannelName, encoded->data(), encoded->size(),
+      [&](const uint8_t* reply, size_t reply_size) {
+        JsonMethodCodec::GetInstance().DecodeAndProcessResponseEnvelope(
+            reply, reply_size, &result);
+      }));
+}
+
+}  // namespace testing
+}  // namespace flutter

From bc6d7d8de03b755c3492724435b291fd190653d8 Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Mon, 18 Apr 2022 13:56:25 -0700
Subject: [PATCH 14/16] Code review: No optional needed

---
 shell/platform/windows/platform_handler_win32.cc | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/shell/platform/windows/platform_handler_win32.cc b/shell/platform/windows/platform_handler_win32.cc
index 038f269fbbde1..dac80a0e5a9b5 100644
--- a/shell/platform/windows/platform_handler_win32.cc
+++ b/shell/platform/windows/platform_handler_win32.cc
@@ -150,11 +150,11 @@ std::variant<std::wstring, int> ScopedClipboard::GetString() {
     return ::GetLastError();
   }
   ScopedGlobalLock locked_data(data);
-  std::optional<std::wstring> string = static_cast<wchar_t*>(locked_data.get());
-  if (!string) {
+
+  if (!locked_data.get()) {
     return ::GetLastError();
   }
-  return string.value();
+  return static_cast<wchar_t*>(locked_data.get());
 }
 
 int ScopedClipboard::SetString(const std::wstring string) {

From 58f2da5e2ef8006fde2067c13b50006b6e95ecc0 Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Mon, 2 May 2022 14:56:57 -0700
Subject: [PATCH 15/16] Review: override annotations

---
 .../platform/windows/platform_handler_win32_unittests.cc  | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/shell/platform/windows/platform_handler_win32_unittests.cc b/shell/platform/windows/platform_handler_win32_unittests.cc
index be503014f36f6..662950c8f270c 100644
--- a/shell/platform/windows/platform_handler_win32_unittests.cc
+++ b/shell/platform/windows/platform_handler_win32_unittests.cc
@@ -41,13 +41,13 @@ class TestScopedClipboard : public ScopedClipboardInterface {
   TestScopedClipboard(TestScopedClipboard const&) = delete;
   TestScopedClipboard& operator=(TestScopedClipboard const&) = delete;
 
-  int Open(HWND window);
+  int Open(HWND window) override;
 
-  bool HasString();
+  bool HasString() override;
 
-  std::variant<std::wstring, int> GetString();
+  std::variant<std::wstring, int> GetString() override;
 
-  int SetString(const std::wstring string);
+  int SetString(const std::wstring string) override;
 
  private:
   bool opened_ = false;

From 853c6ee63fde1fb08ba9d47487f823a9672e8ef9 Mon Sep 17 00:00:00 2001
From: Justin McCandless <jmccandless@google.com>
Date: Mon, 2 May 2022 14:58:41 -0700
Subject: [PATCH 16/16] Review: error code constant

---
 shell/platform/windows/platform_handler_win32_unittests.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/shell/platform/windows/platform_handler_win32_unittests.cc b/shell/platform/windows/platform_handler_win32_unittests.cc
index 662950c8f270c..9d350857640f9 100644
--- a/shell/platform/windows/platform_handler_win32_unittests.cc
+++ b/shell/platform/windows/platform_handler_win32_unittests.cc
@@ -28,6 +28,7 @@ static constexpr char kTextPlainFormat[] = "text/plain";
 static constexpr char kValueKey[] = "value";
 static constexpr int kAccessDeniedErrorCode = 5;
 static constexpr int kErrorSuccess = 0;
+static constexpr int kArbitraryErrorCode = 1;
 
 }  // namespace
 
@@ -208,7 +209,8 @@ TEST(PlatformHandlerWin32, HasStringsError) {
       std::make_unique<::testing::NiceMock<MockWindowBindingHandler>>());
   // HasStrings will fail.
   PlatformHandlerWin32 platform_handler(
-      &messenger, &view, std::make_unique<TestScopedClipboard>(1, true));
+      &messenger, &view,
+      std::make_unique<TestScopedClipboard>(kArbitraryErrorCode, true));
 
   auto args = std::make_unique<rapidjson::Document>(rapidjson::kStringType);
   auto& allocator = args->GetAllocator();