[Extensions Bindings] Add chrome.runtime.lastError support

extensions/renderer/api_last_error_unittest.cc

+// Copyright 2017 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 "extensions/renderer/api_last_error.h"
+
+#include "base/bind.h"
+#include "base/callback_helpers.h"
+#include "extensions/renderer/api_binding_test.h"
+#include "extensions/renderer/api_binding_test_util.h"
+#include "gin/converter.h"
+#include "gin/public/context_holder.h"
+
+namespace extensions {
+
+namespace {
+
+std::string GetLastError(v8::Local<v8::Object> parent,
+                         v8::Local<v8::Context> context) {
+  v8::Local<v8::Value> last_error =
+      GetPropertyFromObject(parent, context, "lastError");
+  if (last_error.IsEmpty() || !last_error->IsObject())
+    return V8ToString(last_error, context);
+  v8::Local<v8::Value> message =
+      GetPropertyFromObject(last_error.As<v8::Object>(), context, "message");
+  return V8ToString(message, context);
+}
+
+using ParentList =
+    std::vector<std::pair<v8::Local<v8::Context>, v8::Local<v8::Object>>>;
+v8::Local<v8::Object> GetParent(
+    const ParentList& parents,
+    v8::Local<v8::Context> context) {
+  // This would be simpler with a map<context, object>, but Local<> doesn't
+  // define an operator<.
+  for (const auto& parent : parents) {
+    if (parent.first == context)
+      return parent.second;
+  }
+  return v8::Local<v8::Object>();
+}
+
+}  // namespace
+
+using APILastErrorTest = APIBindingTest;
+
+// Test basic functionality of the lastError object.
+TEST_F(APILastErrorTest, TestLastError) {
+  v8::HandleScope handle_scope(isolate());
+  v8::Local<v8::Context> context = ContextLocal();
+  v8::Local<v8::Object> parent_object = v8::Object::New(isolate());
+
+  ParentList parents = {{context, parent_object}};
+  APILastError last_error(base::Bind(&GetParent, parents));
+
+  EXPECT_EQ("undefined", GetLastError(parent_object, context));
+
+  last_error.SetError(context, "Some last error");
+  EXPECT_EQ("\"Some last error\"", GetLastError(parent_object, context));
+
+  last_error.ClearError(context, false);
+  EXPECT_EQ("undefined", GetLastError(parent_object, context));
+}
+
+// Test throwing an error if the last error wasn't checked.
+TEST_F(APILastErrorTest, ReportIfUnchecked) {
+  v8::HandleScope handle_scope(isolate());
+  v8::Local<v8::Context> context = ContextLocal();
+  v8::Local<v8::Object> parent_object = v8::Object::New(isolate());
+
+  ParentList parents = {{context, parent_object}};
+  APILastError last_error(base::Bind(&GetParent, parents));
+
+  {
+    v8::TryCatch try_catch(isolate());

[jbroman, 2017/02/06 18:31:26]

nit: whichever you prefer, but you could reuse the same TryCatch and just Reset
it between the two; then you wouldn't need the block nesting

[Devlin, 2017/02/06 20:28:22]

I actually slightly prefer this - it makes it easier to separate out the test
cases visually.  If you have a strong preference the other way, I can combine
them, but otherwise, I'd say we can leave it.

+    last_error.SetError(context, "foo");
+    // GetLastError() will count as accessing the error property, so we
+    // shouldn't throw an exception.
+    EXPECT_EQ("\"foo\"", GetLastError(parent_object, context));
+    last_error.ClearError(context, true);
+    EXPECT_FALSE(try_catch.HasCaught());
+  }
+
+  {
+    v8::TryCatch try_catch(isolate());
+    // This time, we should throw an exception.
+    last_error.SetError(context, "A last error");
+    last_error.ClearError(context, true);
+    EXPECT_TRUE(try_catch.HasCaught());
+    EXPECT_EQ("Uncaught Error: A last error",
+              gin::V8ToString(try_catch.Message()->Get()));
+  }
+}
+
+// Test behavior when something else sets a lastError property on the parent
+// object.
+TEST_F(APILastErrorTest, NonLastErrorObject) {
+  v8::HandleScope handle_scope(isolate());
+  v8::Local<v8::Context> context = ContextLocal();
+  v8::Local<v8::Object> parent_object = v8::Object::New(isolate());
+
+  ParentList parents = {{context, parent_object}};
+  APILastError last_error(base::Bind(&GetParent, parents));
+
+  auto checked_set = [context](v8::Local<v8::Object> object,
+                              base::StringPiece key,
+                              v8::Local<v8::Value> value) {
+    v8::Maybe<bool> success =
+        object->Set(context, gin::StringToSymbol(context->GetIsolate(), key),
+                    value);
+    ASSERT_TRUE(success.IsJust());
+    ASSERT_TRUE(success.FromJust());
+  };
+
+  // Set a "fake" lastError property on the parent.
+  v8::Local<v8::Object> fake_last_error = v8::Object::New(isolate());
+  checked_set(fake_last_error, "message",
+              gin::StringToV8(isolate(), "fake error"));
+  checked_set(parent_object, "lastError", fake_last_error);
+
+  EXPECT_EQ("\"fake error\"", GetLastError(parent_object, context));
+
+  // The bindings shouldn't mangle an existing property.
+  // TODO(devlin): Or should we? If someone sets chrome.runtime.lastError, it
+  // might be the right course of action to overwrite it.
+  last_error.SetError(context, "Real last error");
+  EXPECT_EQ("\"fake error\"", GetLastError(parent_object, context));
+  last_error.ClearError(context, false);
+  EXPECT_EQ("\"fake error\"", GetLastError(parent_object, context));
+}
+
+// Test lastError in multiple different contexts.
+TEST_F(APILastErrorTest, MultipleContexts) {
+  v8::HandleScope handle_scope(isolate());
+  v8::Local<v8::Context> context_a = ContextLocal();
+  v8::Local<v8::Context> context_b = v8::Context::New(isolate());
+  gin::ContextHolder holder_b(isolate());
+  holder_b.SetContext(context_b);
+
+  v8::Local<v8::Object> parent_a = v8::Object::New(isolate());
+  v8::Local<v8::Object> parent_b = v8::Object::New(isolate());
+  ParentList parents = {{context_a, parent_a}, {context_b, parent_b}};
+  APILastError last_error(base::Bind(&GetParent, parents));
+
+  last_error.SetError(context_a, "Last error a");
+  EXPECT_EQ("\"Last error a\"", GetLastError(parent_a, context_a));
+  EXPECT_EQ("undefined", GetLastError(parent_b, context_b));
+
+  last_error.SetError(context_b, "Last error b");
+  EXPECT_EQ("\"Last error a\"", GetLastError(parent_a, context_a));
+  EXPECT_EQ("\"Last error b\"", GetLastError(parent_b, context_b));
+
+  last_error.ClearError(context_b, false);
+  EXPECT_EQ("\"Last error a\"", GetLastError(parent_a, context_a));
+  EXPECT_EQ("undefined", GetLastError(parent_b, context_b));
+
+  last_error.ClearError(context_a, false);
+  EXPECT_EQ("undefined", GetLastError(parent_a, context_a));
+  EXPECT_EQ("undefined", GetLastError(parent_b, context_b));
+}
+
+}  // namespace extensions