[Mojo] Add [Native] type traits for base::Values

mojo/common/common_custom_types_unittest.cc

 // Copyright 2016 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 "base/bind.h"
 #include "base/files/file_path.h"
+#include "base/json/json_writer.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
+#include "base/strings/stringprintf.h"
+#include "base/values.h"
 #include "mojo/common/common_custom_types.mojom.h"
 #include "mojo/common/test_common_custom_types.mojom.h"
 #include "mojo/public/cpp/bindings/binding.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace mojo {
 namespace common {
 namespace test {
+namespace {
 
 class TestFilePathImpl : public TestFilePath {
  public:
   explicit TestFilePathImpl(TestFilePathRequest request)
       : binding_(this, std::move(request)) {}
 
   // TestFilePath implementation:
   void BounceFilePath(const base::FilePath& in,
                       const BounceFilePathCallback& callback) override {
     callback.Run(in);
   }
 
  private:
   mojo::Binding<TestFilePath> binding_;
 };
 
+class TestValueImpl : public TestValue {
+ public:
+  explicit TestValueImpl(TestValueRequest request)
+      : binding_(this, std::move(request)) {}
+
+  // TestValue implementation:
+  void BounceDictionaryValue(
+      const base::DictionaryValue& in,
+      const BounceDictionaryValueCallback& callback) override {
+    callback.Run(in);
+  }
+  void BounceListValue(
+      const base::ListValue& in,
+      const BounceListValueCallback& callback) override {
+    callback.Run(in);
+  }
+
+ private:
+  mojo::Binding<TestValue> binding_;
+};
+
+template<typename C, typename V>
+bool IsBouncedValueEqual(const C& callback,
+                         const V& value,
+                         std::string* error) {
+  base::RunLoop run_loop;
+  bool is_equal = false;
+  callback.Run(value, [&run_loop, &value, &is_equal, &error](
+                          const V& out) {
+    is_equal = value.Equals(&out);
+    if (!is_equal) {
+      std::string in_json;
+      base::JSONWriter::Write(value, &in_json);
+      std::string out_json;
+      base::JSONWriter::Write(out, &out_json);
+      *error = base::StringPrintf("Expected: '%s'; Found: '%s'",
+                                  in_json.c_str(), out_json.c_str());
+    }
+    run_loop.Quit();
+  });
+  run_loop.Run();
+  return is_equal;
+}
+
+}  // namespace
+
 TEST(CommonCustomTypesTest, FilePath) {
   base::MessageLoop message_loop;
   base::RunLoop run_loop;
 
   TestFilePathPtr ptr;
   TestFilePathImpl impl(GetProxy(&ptr));
 
   base::FilePath dir(FILE_PATH_LITERAL("hello"));
   base::FilePath file = dir.Append(FILE_PATH_LITERAL("world"));
 
   ptr->BounceFilePath(file, [&run_loop, &file](const base::FilePath& out) {
     EXPECT_EQ(file, out);
     run_loop.Quit();
   });
 
   run_loop.Run();
 }
 
+TEST(CommonCustomTypesTest, Value) {
+  base::MessageLoop message_loop;

[yzshen1, 2016/05/24 17:54:41]

Please consider moving this into a test fixture class, now that every test needs
it.

[Devlin, 2016/05/24 18:05:56]

Done.

+
+  TestValuePtr ptr;
+  TestValueImpl impl(GetProxy(&ptr));
+  std::string error;
+
+  auto TestDictEqual = [&ptr, &error](const base::DictionaryValue& value) {

[yzshen1, 2016/05/24 17:54:41]

I feel that this testing code is fairly hard to read. Comparing with simply:

- Construct the value.
- Directly call Bounce*Value() with the value.
- Check equity.

But that may be just my personal preference. So please consider this optional.

[Devlin, 2016/05/24 18:05:56]

Agreed.  This had a lot more value when we were testing 7 types of values
instead of 2.

+    return IsBouncedValueEqual(
+        base::Bind(&TestValue::BounceDictionaryValue,
+                   base::Unretained(ptr.get())),
+        value, &error);
+  };
+  auto TestListEqual = [&ptr, &error](const base::ListValue& value) {
+    return IsBouncedValueEqual(
+        base::Bind(&TestValue::BounceListValue,
+                   base::Unretained(ptr.get())),
+        value, &error);
+  };
+
+  base::DictionaryValue dict;
+  dict.SetBoolean("bool", false);
+  dict.SetInteger("int", 2);
+  dict.SetString("string", "some string");
+  dict.SetBoolean("nested.bool", true);
+  dict.SetInteger("nested.int", 9);
+  dict.Set("some_binary", base::WrapUnique(
+      base::BinaryValue::CreateWithCopiedBuffer("mojo", 4)));
+  {
+    std::unique_ptr<base::ListValue> dict_list(new base::ListValue());
+    dict_list->AppendString("string");
+    dict_list->AppendBoolean(true);
+    dict.Set("list", std::move(dict_list));
+  }
+  EXPECT_TRUE(TestDictEqual(dict)) << error;
+
+  base::ListValue list;
+  list.AppendString("string");
+  list.AppendDouble(42.1);
+  list.AppendBoolean(true);
+  list.Append(base::WrapUnique(
+      base::BinaryValue::CreateWithCopiedBuffer("mojo", 4)));
+  {
+    std::unique_ptr<base::DictionaryValue> list_dict(
+        new base::DictionaryValue());
+    list_dict->SetString("string", "str");
+    list.Append(std::move(list_dict));
+  }
+  EXPECT_TRUE(TestListEqual(list)) << error;
+}
+
 }  // namespace test
 }  // namespace common
 }  // namespace mojo