components/dbus/utils/variant_unittest.cc - chromium/src - Git at Google

 // Copyright 2025 The Chromium Authors
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "components/dbus/utils/variant.h"

 #include <map>
 #include <memory>
 #include <string>
 #include <tuple>
 #include <utility>
 #include <vector>

 #include "components/dbus/utils/read_value.h"
 #include "components/dbus/utils/write_value.h"
 #include "dbus/message.h"
 #include "testing/gtest/include/gtest/gtest.h"

 namespace dbus_utils {
 namespace {

 TEST(DBusVariantTest, DefaultConstruction) {
   Variant v;
   EXPECT_TRUE(v.signature().empty());
 }

 TEST(DBusVariantTest, WrapSignature) {
   using TestTuple = std::tuple<int32_t, std::string>;
   using TestMap = std::map<uint16_t, bool>;
   using TestVector = std::vector<double>;

   EXPECT_EQ(Variant::Wrap<"b">(true).signature(), "b");
   EXPECT_EQ(Variant::Wrap<"y">(uint8_t{1}).signature(), "y");
   EXPECT_EQ(Variant::Wrap<"n">(int16_t{2}).signature(), "n");
   EXPECT_EQ(Variant::Wrap<"q">(uint16_t{3}).signature(), "q");
   EXPECT_EQ(Variant::Wrap<"i">(int32_t{4}).signature(), "i");
   EXPECT_EQ(Variant::Wrap<"u">(uint32_t{5}).signature(), "u");
   EXPECT_EQ(Variant::Wrap<"x">(int64_t{6}).signature(), "x");
   EXPECT_EQ(Variant::Wrap<"t">(uint64_t{7}).signature(), "t");
   EXPECT_EQ(Variant::Wrap<"d">(8.0).signature(), "d");
   EXPECT_EQ(Variant::Wrap<"s">(std::string("nine")).signature(), "s");
   EXPECT_EQ(Variant::Wrap<"o">(dbus::ObjectPath("/ten")).signature(), "o");
   EXPECT_EQ(Variant::Wrap<"h">(base::ScopedFD()).signature(), "h");

   // Containers
   EXPECT_EQ(Variant::Wrap<"ad">(TestVector{1.0}).signature(), "ad");
   EXPECT_EQ(Variant::Wrap<"a{qb}">(TestMap{{1, true}}).signature(), "a{qb}");
   EXPECT_EQ(Variant::Wrap<"(is)">(TestTuple{1, "s"}).signature(), "(is)");

   // Nested Variant
   auto inner_variant = Variant::Wrap<"s">(std::string("hello"));
   auto outer_variant = Variant::Wrap<"v">(std::move(inner_variant));
   EXPECT_EQ(outer_variant.signature(), "v");
 }

 TEST(DBusVariantTest, VariantRoundTripString) {
   const std::string kInnerString = "hello variant";

   auto original_variant = dbus_utils::Variant::Wrap<"s">(kInnerString);
   EXPECT_EQ(original_variant.signature(), "s");

   std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
   dbus::MessageWriter writer(response.get());
   internal::WriteValue(writer, original_variant);

   // Test correct type retrieval and signature on Read
   dbus::MessageReader reader(response.get());
   auto variant_read_back = internal::ReadValue<dbus_utils::Variant>(reader);
   ASSERT_TRUE(variant_read_back) << "Failed to read variant";
   EXPECT_EQ(variant_read_back->signature(), "s");

   auto str_opt = std::move(*variant_read_back).Take<std::string>();
   ASSERT_TRUE(str_opt.has_value());
   EXPECT_EQ(*str_opt, kInnerString);
   EXPECT_TRUE(variant_read_back->signature().empty());  // Emptied after Take

   // Test type mismatch clears signature
   dbus::MessageReader reader_for_mismatch(response.get());
   auto variant_for_mismatch =
       internal::ReadValue<dbus_utils::Variant>(reader_for_mismatch);
   ASSERT_TRUE(variant_for_mismatch)
       << "Failed to read variant for mismatch test";
   EXPECT_EQ(variant_for_mismatch->signature(), "s");
   auto int_opt = std::move(*variant_for_mismatch).Take<int32_t>();
   EXPECT_FALSE(int_opt.has_value());
   EXPECT_TRUE(variant_for_mismatch->signature().empty());
 }

 TEST(DBusVariantTest, VariantRoundTripInt32) {
   const int32_t kInnerInt = 42;

   auto original_variant = dbus_utils::Variant::Wrap<"i">(kInnerInt);
   EXPECT_EQ(original_variant.signature(), "i");
   std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
   dbus::MessageWriter writer(response.get());
   internal::WriteValue(writer, original_variant);

   // Test correct type retrieval
   dbus::MessageReader reader(response.get());
   auto variant_read_back = internal::ReadValue<dbus_utils::Variant>(reader);
   ASSERT_TRUE(variant_read_back) << "Failed to read variant";
   EXPECT_EQ(variant_read_back->signature(), "i");

   auto int_opt = std::move(*variant_read_back).Take<int32_t>();
   ASSERT_TRUE(int_opt.has_value());
   EXPECT_EQ(*int_opt, kInnerInt);
   EXPECT_TRUE(variant_read_back->signature().empty());
 }

 TEST(DBusVariantTest, VariantRoundTripTestStruct2) {
   using TestTuple = std::tuple<int32_t, std::string, std::vector<double>>;
   const TestTuple kExpectedData = {101, "complex", {1.5, 2.5, 3.5}};

   auto original_variant = Variant::Wrap<"(isad)">(kExpectedData);
   EXPECT_EQ(original_variant.signature(), "(isad)");
   std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
   dbus::MessageWriter writer(response.get());
   internal::WriteValue(writer, original_variant);

   dbus::MessageReader reader(response.get());
   auto variant_read_back = internal::ReadValue<Variant>(reader);
   ASSERT_TRUE(variant_read_back) << "Failed to read variant";
   EXPECT_EQ(variant_read_back->signature(), "(isad)");

   auto data_read = std::move(*variant_read_back).Take<TestTuple>();
   EXPECT_TRUE(variant_read_back->signature().empty());
   ASSERT_TRUE(data_read.has_value());
   EXPECT_EQ(*data_read, kExpectedData);
 }

 TEST(DBusVariantTest, VariantRoundTripMap) {
   const std::map<std::string, int32_t> kInnerMap = {
       {"one", 1}, {"two", 2}, {"three", 3}};

   auto original_variant = dbus_utils::Variant::Wrap<"a{si}">(kInnerMap);
   EXPECT_EQ(original_variant.signature(), "a{si}");
   std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
   dbus::MessageWriter writer(response.get());
   internal::WriteValue(writer, original_variant);

   dbus::MessageReader reader(response.get());
   auto variant_read_back = internal::ReadValue<dbus_utils::Variant>(reader);
   ASSERT_TRUE(variant_read_back) << "Failed to read variant";
   EXPECT_EQ(variant_read_back->signature(), "a{si}");

   auto map_opt =
       std::move(*variant_read_back).Take<std::map<std::string, int32_t>>();
   ASSERT_TRUE(map_opt.has_value());
   EXPECT_TRUE(variant_read_back->signature().empty());
   EXPECT_EQ(*map_opt, kInnerMap);
 }

 TEST(DBusVariantTest, VariantRoundTripVectorOfTuples) {
   using TestSimpleTuple = std::tuple<int32_t, std::string>;
   const std::vector<TestSimpleTuple> kInnerVec = {{1, "a"}, {2, "b"}};

   auto original_variant = dbus_utils::Variant::Wrap<"a(is)">(kInnerVec);
   EXPECT_EQ(original_variant.signature(), "a(is)");
   std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
   dbus::MessageWriter writer(response.get());
   internal::WriteValue(writer, original_variant);

   dbus::MessageReader reader(response.get());
   auto variant_read_back = internal::ReadValue<dbus_utils::Variant>(reader);
   ASSERT_TRUE(variant_read_back) << "Failed to read variant";
   EXPECT_EQ(variant_read_back->signature(), "a(is)");

   auto vec_opt =
       std::move(*variant_read_back).Take<std::vector<TestSimpleTuple>>();
   ASSERT_TRUE(vec_opt.has_value());
   EXPECT_TRUE(variant_read_back->signature().empty());
   EXPECT_EQ(*vec_opt, kInnerVec);
 }

 TEST(DBusVariantTest, VariantRoundTripArrayOfInts) {
   const std::vector<int32_t> kInnerArray = {1, 2, 3, 4};

   auto original_variant = dbus_utils::Variant::Wrap<"ai">(kInnerArray);
   EXPECT_EQ(original_variant.signature(), "ai");
   std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
   dbus::MessageWriter writer(response.get());
   internal::WriteValue(writer, original_variant);

   dbus::MessageReader reader(response.get());
   auto variant_read_back = internal::ReadValue<dbus_utils::Variant>(reader);
   ASSERT_TRUE(variant_read_back) << "Failed to read variant";
   EXPECT_EQ(variant_read_back->signature(), "ai");

   auto vec_opt = std::move(*variant_read_back).Take<std::vector<int32_t>>();
   ASSERT_TRUE(vec_opt.has_value());
   EXPECT_TRUE(variant_read_back->signature().empty());
   EXPECT_EQ(*vec_opt, kInnerArray);
 }

 TEST(DBusVariantTest, VariantOfVariantHoldingInt) {
   auto original_outer_variant = dbus_utils::Variant::Wrap<"v">(
       dbus_utils::Variant::Wrap<"i">(static_cast<int32_t>(12345)));
   EXPECT_EQ(original_outer_variant.signature(), "v");

   std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
   dbus::MessageWriter writer(response.get());
   internal::WriteValue(writer, original_outer_variant);

   dbus::MessageReader reader(response.get());
   auto outer_variant_read_back =
       internal::ReadValue<dbus_utils::Variant>(reader);
   ASSERT_TRUE(outer_variant_read_back) << "Failed to read outer variant";
   EXPECT_EQ(outer_variant_read_back->signature(), "v");
   EXPECT_FALSE(reader.HasMoreData());

   auto inner_variant_opt =
       std::move(*outer_variant_read_back).Take<dbus_utils::Variant>();
   EXPECT_TRUE(outer_variant_read_back->signature().empty());
   ASSERT_TRUE(inner_variant_opt.has_value())
       << "Outer variant did not contain an inner variant.";
   EXPECT_EQ(inner_variant_opt->signature(), "i");

   // Test successful Get from inner variant.
   auto int_opt = std::move(*inner_variant_opt).Take<int32_t>();
   ASSERT_TRUE(int_opt.has_value())
       << "Inner variant did not contain an int32_t.";
   EXPECT_EQ(*int_opt, 12345);
   EXPECT_TRUE(inner_variant_opt->signature().empty());
 }

 TEST(DBusVariantTest, VariantGetTypeSafety) {
   const int32_t kInnerInt = 99;
   auto original_variant = dbus_utils::Variant::Wrap<"i">(kInnerInt);
   std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
   dbus::MessageWriter writer(response.get());
   internal::WriteValue(writer, original_variant);

   // Read the variant and try to Get the wrong type.
   dbus::MessageReader reader1(response.get());
   auto variant1 = internal::ReadValue<dbus_utils::Variant>(reader1);
   ASSERT_TRUE(variant1);
   auto str_opt = std::move(*variant1).Take<std::string>();
   EXPECT_FALSE(str_opt.has_value());

   // The variant is not consumed on failed Take. Read it again to Get the
   // correct type.
   dbus::MessageReader reader2(response.get());
   auto variant = internal::ReadValue<dbus_utils::Variant>(reader2);
   ASSERT_TRUE(variant);
   EXPECT_EQ(variant->signature(), "i");
   auto int_opt = std::move(*variant).Take<int32_t>();
   ASSERT_TRUE(int_opt.has_value());
   EXPECT_EQ(*int_opt, kInnerInt);
 }

 TEST(DBusVariantTest, VariantIsEmptyAfterSuccessfulTake) {
   auto variant = Variant::Wrap<"s">(std::string("some string"));

   // Take the value. This consumes the variant.
   auto value = std::move(variant).Take<std::string>();
   ASSERT_TRUE(value.has_value());

   // The variant is now in a moved-from state, which the implementation defines
   // as empty.
   EXPECT_TRUE(variant.signature().empty());
 }

 TEST(DBusVariantTest, VariantIsEmptyAfterFailedTake) {
   auto variant = Variant::Wrap<"s">(std::string("another string"));
   ASSERT_EQ(variant.signature(), "s");

   // Attempt to take the wrong type.
   auto wrong_value = std::move(variant).Take<int32_t>();
   ASSERT_FALSE(wrong_value.has_value());

   // The variant should have been cleared.
   EXPECT_TRUE(variant.signature().empty());
 }

 }  // namespace
 }  // namespace dbus_utils
	// Copyright 2025 The Chromium Authors
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "components/dbus/utils/variant.h"

	#include <map>
	#include <memory>
	#include <string>
	#include <tuple>
	#include <utility>
	#include <vector>

	#include "components/dbus/utils/read_value.h"
	#include "components/dbus/utils/write_value.h"
	#include "dbus/message.h"
	#include "testing/gtest/include/gtest/gtest.h"

	namespace dbus_utils {
	namespace {

	TEST(DBusVariantTest, DefaultConstruction) {
	Variant v;
	EXPECT_TRUE(v.signature().empty());
	}

	TEST(DBusVariantTest, WrapSignature) {
	using TestTuple = std::tuple<int32_t, std::string>;
	using TestMap = std::map<uint16_t, bool>;
	using TestVector = std::vector<double>;

	EXPECT_EQ(Variant::Wrap<"b">(true).signature(), "b");
	EXPECT_EQ(Variant::Wrap<"y">(uint8_t{1}).signature(), "y");
	EXPECT_EQ(Variant::Wrap<"n">(int16_t{2}).signature(), "n");
	EXPECT_EQ(Variant::Wrap<"q">(uint16_t{3}).signature(), "q");
	EXPECT_EQ(Variant::Wrap<"i">(int32_t{4}).signature(), "i");
	EXPECT_EQ(Variant::Wrap<"u">(uint32_t{5}).signature(), "u");
	EXPECT_EQ(Variant::Wrap<"x">(int64_t{6}).signature(), "x");
	EXPECT_EQ(Variant::Wrap<"t">(uint64_t{7}).signature(), "t");
	EXPECT_EQ(Variant::Wrap<"d">(8.0).signature(), "d");
	EXPECT_EQ(Variant::Wrap<"s">(std::string("nine")).signature(), "s");
	EXPECT_EQ(Variant::Wrap<"o">(dbus::ObjectPath("/ten")).signature(), "o");
	EXPECT_EQ(Variant::Wrap<"h">(base::ScopedFD()).signature(), "h");

	// Containers
	EXPECT_EQ(Variant::Wrap<"ad">(TestVector{1.0}).signature(), "ad");
	EXPECT_EQ(Variant::Wrap<"a{qb}">(TestMap{{1, true}}).signature(), "a{qb}");
	EXPECT_EQ(Variant::Wrap<"(is)">(TestTuple{1, "s"}).signature(), "(is)");

	// Nested Variant
	auto inner_variant = Variant::Wrap<"s">(std::string("hello"));
	auto outer_variant = Variant::Wrap<"v">(std::move(inner_variant));
	EXPECT_EQ(outer_variant.signature(), "v");
	}

	TEST(DBusVariantTest, VariantRoundTripString) {
	const std::string kInnerString = "hello variant";

	auto original_variant = dbus_utils::Variant::Wrap<"s">(kInnerString);
	EXPECT_EQ(original_variant.signature(), "s");

	std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
	dbus::MessageWriter writer(response.get());
	internal::WriteValue(writer, original_variant);

	// Test correct type retrieval and signature on Read
	dbus::MessageReader reader(response.get());
	auto variant_read_back = internal::ReadValue<dbus_utils::Variant>(reader);
	ASSERT_TRUE(variant_read_back) << "Failed to read variant";
	EXPECT_EQ(variant_read_back->signature(), "s");

	auto str_opt = std::move(*variant_read_back).Take<std::string>();
	ASSERT_TRUE(str_opt.has_value());
	EXPECT_EQ(*str_opt, kInnerString);
	EXPECT_TRUE(variant_read_back->signature().empty()); // Emptied after Take

	// Test type mismatch clears signature
	dbus::MessageReader reader_for_mismatch(response.get());
	auto variant_for_mismatch =
	internal::ReadValue<dbus_utils::Variant>(reader_for_mismatch);
	ASSERT_TRUE(variant_for_mismatch)
	<< "Failed to read variant for mismatch test";
	EXPECT_EQ(variant_for_mismatch->signature(), "s");
	auto int_opt = std::move(*variant_for_mismatch).Take<int32_t>();
	EXPECT_FALSE(int_opt.has_value());
	EXPECT_TRUE(variant_for_mismatch->signature().empty());
	}

	TEST(DBusVariantTest, VariantRoundTripInt32) {
	const int32_t kInnerInt = 42;

	auto original_variant = dbus_utils::Variant::Wrap<"i">(kInnerInt);
	EXPECT_EQ(original_variant.signature(), "i");
	std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
	dbus::MessageWriter writer(response.get());
	internal::WriteValue(writer, original_variant);

	// Test correct type retrieval
	dbus::MessageReader reader(response.get());
	auto variant_read_back = internal::ReadValue<dbus_utils::Variant>(reader);
	ASSERT_TRUE(variant_read_back) << "Failed to read variant";
	EXPECT_EQ(variant_read_back->signature(), "i");

	auto int_opt = std::move(*variant_read_back).Take<int32_t>();
	ASSERT_TRUE(int_opt.has_value());
	EXPECT_EQ(*int_opt, kInnerInt);
	EXPECT_TRUE(variant_read_back->signature().empty());
	}

	TEST(DBusVariantTest, VariantRoundTripTestStruct2) {
	using TestTuple = std::tuple<int32_t, std::string, std::vector<double>>;
	const TestTuple kExpectedData = {101, "complex", {1.5, 2.5, 3.5}};

	auto original_variant = Variant::Wrap<"(isad)">(kExpectedData);
	EXPECT_EQ(original_variant.signature(), "(isad)");
	std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
	dbus::MessageWriter writer(response.get());
	internal::WriteValue(writer, original_variant);

	dbus::MessageReader reader(response.get());
	auto variant_read_back = internal::ReadValue<Variant>(reader);
	ASSERT_TRUE(variant_read_back) << "Failed to read variant";
	EXPECT_EQ(variant_read_back->signature(), "(isad)");

	auto data_read = std::move(*variant_read_back).Take<TestTuple>();
	EXPECT_TRUE(variant_read_back->signature().empty());
	ASSERT_TRUE(data_read.has_value());
	EXPECT_EQ(*data_read, kExpectedData);
	}

	TEST(DBusVariantTest, VariantRoundTripMap) {
	const std::map<std::string, int32_t> kInnerMap = {
	{"one", 1}, {"two", 2}, {"three", 3}};

	auto original_variant = dbus_utils::Variant::Wrap<"a{si}">(kInnerMap);
	EXPECT_EQ(original_variant.signature(), "a{si}");
	std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
	dbus::MessageWriter writer(response.get());
	internal::WriteValue(writer, original_variant);

	dbus::MessageReader reader(response.get());
	auto variant_read_back = internal::ReadValue<dbus_utils::Variant>(reader);
	ASSERT_TRUE(variant_read_back) << "Failed to read variant";
	EXPECT_EQ(variant_read_back->signature(), "a{si}");

	auto map_opt =
	std::move(*variant_read_back).Take<std::map<std::string, int32_t>>();
	ASSERT_TRUE(map_opt.has_value());
	EXPECT_TRUE(variant_read_back->signature().empty());
	EXPECT_EQ(*map_opt, kInnerMap);
	}

	TEST(DBusVariantTest, VariantRoundTripVectorOfTuples) {
	using TestSimpleTuple = std::tuple<int32_t, std::string>;
	const std::vector<TestSimpleTuple> kInnerVec = {{1, "a"}, {2, "b"}};

	auto original_variant = dbus_utils::Variant::Wrap<"a(is)">(kInnerVec);
	EXPECT_EQ(original_variant.signature(), "a(is)");
	std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
	dbus::MessageWriter writer(response.get());
	internal::WriteValue(writer, original_variant);

	dbus::MessageReader reader(response.get());
	auto variant_read_back = internal::ReadValue<dbus_utils::Variant>(reader);
	ASSERT_TRUE(variant_read_back) << "Failed to read variant";
	EXPECT_EQ(variant_read_back->signature(), "a(is)");

	auto vec_opt =
	std::move(*variant_read_back).Take<std::vector<TestSimpleTuple>>();
	ASSERT_TRUE(vec_opt.has_value());
	EXPECT_TRUE(variant_read_back->signature().empty());
	EXPECT_EQ(*vec_opt, kInnerVec);
	}

	TEST(DBusVariantTest, VariantRoundTripArrayOfInts) {
	const std::vector<int32_t> kInnerArray = {1, 2, 3, 4};

	auto original_variant = dbus_utils::Variant::Wrap<"ai">(kInnerArray);
	EXPECT_EQ(original_variant.signature(), "ai");
	std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
	dbus::MessageWriter writer(response.get());
	internal::WriteValue(writer, original_variant);

	dbus::MessageReader reader(response.get());
	auto variant_read_back = internal::ReadValue<dbus_utils::Variant>(reader);
	ASSERT_TRUE(variant_read_back) << "Failed to read variant";
	EXPECT_EQ(variant_read_back->signature(), "ai");

	auto vec_opt = std::move(*variant_read_back).Take<std::vector<int32_t>>();
	ASSERT_TRUE(vec_opt.has_value());
	EXPECT_TRUE(variant_read_back->signature().empty());
	EXPECT_EQ(*vec_opt, kInnerArray);
	}

	TEST(DBusVariantTest, VariantOfVariantHoldingInt) {
	auto original_outer_variant = dbus_utils::Variant::Wrap<"v">(
	dbus_utils::Variant::Wrap<"i">(static_cast<int32_t>(12345)));
	EXPECT_EQ(original_outer_variant.signature(), "v");

	std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
	dbus::MessageWriter writer(response.get());
	internal::WriteValue(writer, original_outer_variant);

	dbus::MessageReader reader(response.get());
	auto outer_variant_read_back =
	internal::ReadValue<dbus_utils::Variant>(reader);
	ASSERT_TRUE(outer_variant_read_back) << "Failed to read outer variant";
	EXPECT_EQ(outer_variant_read_back->signature(), "v");
	EXPECT_FALSE(reader.HasMoreData());

	auto inner_variant_opt =
	std::move(*outer_variant_read_back).Take<dbus_utils::Variant>();
	EXPECT_TRUE(outer_variant_read_back->signature().empty());
	ASSERT_TRUE(inner_variant_opt.has_value())
	<< "Outer variant did not contain an inner variant.";
	EXPECT_EQ(inner_variant_opt->signature(), "i");

	// Test successful Get from inner variant.
	auto int_opt = std::move(*inner_variant_opt).Take<int32_t>();
	ASSERT_TRUE(int_opt.has_value())
	<< "Inner variant did not contain an int32_t.";
	EXPECT_EQ(*int_opt, 12345);
	EXPECT_TRUE(inner_variant_opt->signature().empty());
	}

	TEST(DBusVariantTest, VariantGetTypeSafety) {
	const int32_t kInnerInt = 99;
	auto original_variant = dbus_utils::Variant::Wrap<"i">(kInnerInt);
	std::unique_ptr<dbus::Response> response = dbus::Response::CreateEmpty();
	dbus::MessageWriter writer(response.get());
	internal::WriteValue(writer, original_variant);

	// Read the variant and try to Get the wrong type.
	dbus::MessageReader reader1(response.get());
	auto variant1 = internal::ReadValue<dbus_utils::Variant>(reader1);
	ASSERT_TRUE(variant1);
	auto str_opt = std::move(*variant1).Take<std::string>();
	EXPECT_FALSE(str_opt.has_value());

	// The variant is not consumed on failed Take. Read it again to Get the
	// correct type.
	dbus::MessageReader reader2(response.get());
	auto variant = internal::ReadValue<dbus_utils::Variant>(reader2);
	ASSERT_TRUE(variant);
	EXPECT_EQ(variant->signature(), "i");
	auto int_opt = std::move(*variant).Take<int32_t>();
	ASSERT_TRUE(int_opt.has_value());
	EXPECT_EQ(*int_opt, kInnerInt);
	}

	TEST(DBusVariantTest, VariantIsEmptyAfterSuccessfulTake) {
	auto variant = Variant::Wrap<"s">(std::string("some string"));

	// Take the value. This consumes the variant.
	auto value = std::move(variant).Take<std::string>();
	ASSERT_TRUE(value.has_value());

	// The variant is now in a moved-from state, which the implementation defines
	// as empty.
	EXPECT_TRUE(variant.signature().empty());
	}

	TEST(DBusVariantTest, VariantIsEmptyAfterFailedTake) {
	auto variant = Variant::Wrap<"s">(std::string("another string"));
	ASSERT_EQ(variant.signature(), "s");

	// Attempt to take the wrong type.
	auto wrong_value = std::move(variant).Take<int32_t>();
	ASSERT_FALSE(wrong_value.has_value());

	// The variant should have been cleared.
	EXPECT_TRUE(variant.signature().empty());
	}

	} // namespace
	} // namespace dbus_utils