Base: add Optional<T>.

base/optional_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/optional.h"
+
+#include <set>
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+namespace {
+
+// Object used to test complex object with Optional<T> in addition of the move
+// semantics.
+class TestObject {
+ public:
+  enum class State {
+    DEFAULT_CONSTRUCTED,
+    VALUE_CONSTRUCTED,
+    COPY_CONSTRUCTED,
+    MOVE_CONSTRUCTED,
+    MOVED_FROM,
+  };
+
+  TestObject() : foo_(0), bar_(0.0), state_(State::DEFAULT_CONSTRUCTED) {}
+
+  TestObject(int foo, double bar)
+      : foo_(foo), bar_(bar), state_(State::VALUE_CONSTRUCTED) {}
+
+  TestObject(const TestObject& other)
+      : foo_(other.foo_), bar_(other.bar_), state_(State::COPY_CONSTRUCTED) {}
+
+  TestObject(TestObject&& other)
+      : foo_(std::move(other.foo_)),
+        bar_(std::move(other.bar_)),
+        state_(State::MOVE_CONSTRUCTED) {
+    other.state_ = State::MOVED_FROM;
+  }
+
+  TestObject& operator=(const TestObject& other) {
+    foo_ = other.foo_;
+    bar_ = other.bar_;
+    state_ = State::COPY_CONSTRUCTED;
+    return *this;
+  }
+
+  bool operator==(const TestObject& other) const {
+    return foo_ == other.foo_ && bar_ == other.bar_;
+  }
+
+  int foo() const { return foo_; }
+  State state() const { return state_; }
+
+ private:
+  int foo_;
+  double bar_;
+  State state_;
+};
+
+}  // anonymous namespace
+
+TEST(OptionalTest, DefaultConstructor) {
+  {
+    Optional<float> o;
+    EXPECT_FALSE(o);
+  }
+
+  {
+    Optional<std::string> o;
+    EXPECT_FALSE(o);
+  }
+
+  {
+    Optional<TestObject> o;
+    EXPECT_FALSE(o);
+  }
+}
+
+TEST(OptionalTest, CopyConstructor) {
+  {
+    Optional<float> first(0.1f);
+    Optional<float> other(first);
+
+    EXPECT_TRUE(other);
+    EXPECT_EQ(other.value(), 0.1f);
+    EXPECT_EQ(first, other);
+  }
+
+  {
+    Optional<std::string> first("foo");
+    Optional<std::string> other(first);
+
+    EXPECT_TRUE(other);
+    EXPECT_EQ(other.value(), "foo");
+    EXPECT_EQ(first, other);
+  }
+
+  {
+    Optional<TestObject> first(TestObject(3, 0.1));
+    Optional<TestObject> other(first);
+
+    EXPECT_TRUE(!!other);
+    EXPECT_TRUE(other.value() == TestObject(3, 0.1));
+    EXPECT_TRUE(first == other);
+  }
+}
+
+TEST(OptionalTest, ValueConstructor) {
+  {
+    Optional<float> o(0.1f);
+    EXPECT_TRUE(o);
+    EXPECT_EQ(o.value(), 0.1f);
+  }
+
+  {
+    Optional<std::string> o("foo");
+    EXPECT_TRUE(o);
+    EXPECT_EQ(o.value(), "foo");
+  }
+
+  {
+    Optional<TestObject> o(TestObject(3, 0.1));
+    EXPECT_TRUE(!!o);
+    EXPECT_TRUE(o.value() == TestObject(3, 0.1));
+  }
+}
+
+TEST(OptionalTest, MoveConstructor) {
+  {
+    Optional<float> first(0.1f);
+    Optional<float> second(std::move(first));
+
+    EXPECT_TRUE(second);
+    EXPECT_EQ(second.value(), 0.1f);
+
+    EXPECT_TRUE(first);
+  }
+
+  {
+    Optional<std::string> first("foo");
+    Optional<std::string> second(std::move(first));
+
+    EXPECT_TRUE(second);
+    EXPECT_EQ("foo", second.value());
+
+    EXPECT_TRUE(first);
+  }
+
+  {
+    Optional<TestObject> first(TestObject(3, 0.1));
+    Optional<TestObject> second(std::move(first));
+
+    EXPECT_TRUE(!!second);
+    EXPECT_EQ(TestObject::State::MOVE_CONSTRUCTED, second->state());
+    EXPECT_TRUE(TestObject(3, 0.1) == second.value());
+
+    EXPECT_TRUE(!!first);
+    EXPECT_EQ(TestObject::State::MOVED_FROM, first->state());
+  }
+}
+
+TEST(OptionalTest, MoveValueConstructor) {
+  {
+    Optional<float> first(0.1f);
+    Optional<float> second(std::move(first.value()));
+
+    EXPECT_TRUE(second);
+    EXPECT_EQ(second.value(), 0.1f);
+
+    EXPECT_TRUE(first);
+  }
+
+  {
+    Optional<std::string> first("foo");
+    Optional<std::string> second(std::move(first.value()));
+
+    EXPECT_TRUE(second);
+    EXPECT_EQ("foo", second.value());
+
+    EXPECT_TRUE(first);
+  }
+
+  {
+    Optional<TestObject> first(TestObject(3, 0.1));
+    Optional<TestObject> second(std::move(first.value()));
+
+    EXPECT_TRUE(!!second);
+    EXPECT_EQ(TestObject::State::MOVE_CONSTRUCTED, second->state());
+    EXPECT_TRUE(TestObject(3, 0.1) == second.value());
+
+    EXPECT_TRUE(!!first);
+    EXPECT_EQ(TestObject::State::MOVED_FROM, first->state());
+  }
+}
+
+TEST(OptionalTest, ConstructorForwardArguments) {
+  {
+    Optional<float> a(base::in_place, 0.1f);
+    EXPECT_TRUE(a);
+    EXPECT_EQ(0.1f, a.value());
+  }
+
+  {
+    Optional<std::string> a(base::in_place, "foo");
+    EXPECT_TRUE(a);
+    EXPECT_EQ("foo", a.value());
+  }
+
+  {
+    Optional<TestObject> a(base::in_place, 0, 0.1);
+    EXPECT_TRUE(!!a);
+    EXPECT_TRUE(TestObject(0, 0.1) == a.value());
+  }
+}
+
+TEST(OptionalTest, AssignValue) {
+  {
+    Optional<float> a;
+    EXPECT_FALSE(a);
+    a = 0.1f;
+    EXPECT_TRUE(a);
+
+    Optional<float> b(0.1f);
+    EXPECT_TRUE(a == b);
+  }
+
+  {
+    // Using |const char*| because |std::string| can't be assigned string
+    // literals because of the decay-only perfect forwarding assignment rule.
+    Optional<const char*> a;
+    EXPECT_FALSE(a);
+    a = "foo";
+    EXPECT_TRUE(a);
+
+    Optional<const char*> b("foo");
+    EXPECT_TRUE(a == b);
+  }
+
+  {
+    Optional<TestObject> a;
+    EXPECT_FALSE(!!a);
+    a = TestObject(3, 0.1);
+    EXPECT_TRUE(!!a);
+
+    Optional<TestObject> b(TestObject(3, 0.1));
+    EXPECT_TRUE(a == b);
+  }
+}
+
+TEST(OptionalTest, AssignObject) {
+  {
+    Optional<float> a;
+    Optional<float> b(0.1f);
+    a = b;
+
+    EXPECT_TRUE(a);
+    EXPECT_EQ(a.value(), 0.1f);
+    EXPECT_EQ(a, b);
+  }
+
+  {
+    Optional<std::string> a;
+    Optional<std::string> b("foo");
+    a = b;
+
+    EXPECT_TRUE(a);
+    EXPECT_EQ(a.value(), "foo");
+    EXPECT_EQ(a, b);
+  }
+
+  {
+    Optional<TestObject> a;
+    Optional<TestObject> b(TestObject(3, 0.1));
+    a = b;
+
+    EXPECT_TRUE(!!a);
+    EXPECT_TRUE(a.value() == TestObject(3, 0.1));
+    EXPECT_TRUE(a == b);
+  }
+}
+
+TEST(OptionalTest, AssignObject_rvalue) {
+  {
+    Optional<float> a;
+    Optional<float> b(0.1f);
+    a = std::move(b);
+
+    EXPECT_TRUE(a);
+    EXPECT_TRUE(b);
+    EXPECT_EQ(0.1f, a.value());
+  }
+
+  {
+    Optional<std::string> a;
+    Optional<std::string> b("foo");
+    a = std::move(b);
+
+    EXPECT_TRUE(a);
+    EXPECT_TRUE(b);
+    EXPECT_EQ("foo", a.value());
+  }
+
+  {
+    Optional<TestObject> a;
+    Optional<TestObject> b(TestObject(3, 0.1));
+    a = std::move(b);
+
+    EXPECT_TRUE(!!a);
+    EXPECT_TRUE(!!b);
+    EXPECT_TRUE(TestObject(3, 0.1) == a.value());
+
+    EXPECT_EQ(TestObject::State::MOVE_CONSTRUCTED, a->state());
+    EXPECT_EQ(TestObject::State::MOVED_FROM, b->state());
+  }
+}
+
+TEST(OptionalTest, AssignNull) {
+  {
+    Optional<float> a(0.1f);
+    Optional<float> b(0.2f);
+    a = base::nullopt;
+    b = base::nullopt;
+    EXPECT_EQ(a, b);
+  }
+
+  {
+    Optional<std::string> a("foo");
+    Optional<std::string> b("bar");
+    a = base::nullopt;
+    b = base::nullopt;
+    EXPECT_EQ(a, b);
+  }
+
+  {
+    Optional<TestObject> a(TestObject(3, 0.1));
+    Optional<TestObject> b(TestObject(4, 1.0));
+    a = base::nullopt;
+    b = base::nullopt;
+    EXPECT_TRUE(a == b);
+  }
+}
+
+TEST(OptionalTest, OperatorStar) {
+  {
+    Optional<float> a(0.1f);
+    EXPECT_EQ(a.value(), *a);
+  }
+
+  {
+    Optional<std::string> a("foo");
+    EXPECT_EQ(a.value(), *a);
+  }
+
+  {
+    Optional<TestObject> a(TestObject(3, 0.1));
+    EXPECT_EQ(a.value(), *a);
+  }
+}
+
+TEST(OptionalTest, OperatorStar_rvalue) {
+  EXPECT_EQ(0.1f, *Optional<float>(0.1f));
+  EXPECT_EQ("foo", *Optional<const char*>("foo"));
+  EXPECT_TRUE(TestObject(3, 0.1) == *Optional<TestObject>(TestObject(3, 0.1)));
+}
+
+TEST(OptionalTest, OperatorArrow) {
+  Optional<TestObject> a(TestObject(3, 0.1));
+  EXPECT_EQ(a->foo(), 3);
+}
+
+TEST(OptionalTest, Value_rvalue) {
+  EXPECT_EQ(0.1f, Optional<float>(0.1f).value());
+  EXPECT_EQ("foo", Optional<const char*>("foo").value());
+  EXPECT_TRUE(TestObject(3, 0.1) ==
+              Optional<TestObject>(TestObject(3, 0.1)).value());
+}
+
+TEST(OptionalTest, ValueOr) {
+  {
+    Optional<float> a;
+    EXPECT_EQ(0.0f, a.value_or(0.0f));
+
+    a = 0.1f;
+    EXPECT_EQ(0.1f, a.value_or(0.0f));
+
+    a = base::nullopt;
+    EXPECT_EQ(0.0f, a.value_or(0.0f));
+  }
+
+  {
+    // Using |const char*| because |std::string| can't be assigned string
+    // literals because of the decay-only perfect forwarding assignment rule.
+    Optional<const char*> a;
+    EXPECT_EQ("bar", a.value_or("bar"));
+
+    a = "foo";
+    EXPECT_EQ("foo", a.value_or("bar"));
+
+    a = base::nullopt;
+    EXPECT_EQ("bar", a.value_or("bar"));
+  }
+
+  {
+    Optional<TestObject> a;
+    EXPECT_TRUE(a.value_or(TestObject(1, 0.3)) == TestObject(1, 0.3));
+
+    a = TestObject(3, 0.1);
+    EXPECT_TRUE(a.value_or(TestObject(1, 0.3)) == TestObject(3, 0.1));
+
+    a = base::nullopt;
+    EXPECT_TRUE(a.value_or(TestObject(1, 0.3)) == TestObject(1, 0.3));
+  }
+}
+
+TEST(OptionalTest, Swap_bothNoValue) {
+  Optional<TestObject> a, b;
+  a.swap(b);
+
+  EXPECT_FALSE(a);
+  EXPECT_FALSE(b);
+  EXPECT_TRUE(TestObject(42, 0.42) == a.value_or(TestObject(42, 0.42)));
+  EXPECT_TRUE(TestObject(42, 0.42) == b.value_or(TestObject(42, 0.42)));
+}
+
+TEST(OptionalTest, Swap_inHasValue) {
+  Optional<TestObject> a(TestObject(1, 0.3));
+  Optional<TestObject> b;
+  a.swap(b);
+
+  EXPECT_FALSE(a);
+
+  EXPECT_TRUE(!!b);
+  EXPECT_TRUE(TestObject(42, 0.42) == a.value_or(TestObject(42, 0.42)));
+  EXPECT_TRUE(TestObject(1, 0.3) == b.value_or(TestObject(42, 0.42)));
+}
+
+TEST(OptionalTest, Swap_outHasValue) {
+  Optional<TestObject> a;
+  Optional<TestObject> b(TestObject(1, 0.3));
+  a.swap(b);
+
+  EXPECT_TRUE(!!a);
+  EXPECT_FALSE(!!b);
+  EXPECT_TRUE(TestObject(1, 0.3) == a.value_or(TestObject(42, 0.42)));
+  EXPECT_TRUE(TestObject(42, 0.42) == b.value_or(TestObject(42, 0.42)));
+}
+
+TEST(OptionalTest, Swap_bothValue) {
+  Optional<TestObject> a(TestObject(0, 0.1));
+  Optional<TestObject> b(TestObject(1, 0.3));
+  a.swap(b);
+
+  EXPECT_TRUE(!!a);
+  EXPECT_TRUE(!!b);
+  EXPECT_TRUE(TestObject(1, 0.3) == a.value_or(TestObject(42, 0.42)));
+  EXPECT_TRUE(TestObject(0, 0.1) == b.value_or(TestObject(42, 0.42)));
+}
+
+TEST(OptionalTest, Emplace) {
+  {
+    Optional<float> a(0.1f);
+    a.emplace(0.3f);
+
+    EXPECT_TRUE(a);
+    EXPECT_EQ(0.3f, a.value());
+  }
+
+  {
+    Optional<std::string> a("foo");
+    a.emplace("bar");
+
+    EXPECT_TRUE(a);
+    EXPECT_EQ("bar", a.value());
+  }
+
+  {
+    Optional<TestObject> a(TestObject(0, 0.1));
+    a.emplace(TestObject(1, 0.2));
+
+    EXPECT_TRUE(!!a);
+    EXPECT_TRUE(TestObject(1, 0.2) == a.value());
+  }
+}
+
+TEST(OptionalTest, Equals_TwoEmpty) {
+  Optional<int> a;
+  Optional<int> b;
+
+  EXPECT_TRUE(a == b);
+}
+
+TEST(OptionalTest, Equals_TwoEquals) {
+  Optional<int> a(1);
+  Optional<int> b(1);
+
+  EXPECT_TRUE(a == b);
+}
+
+TEST(OptionalTest, Equals_OneEmpty) {
+  Optional<int> a;
+  Optional<int> b(1);
+
+  EXPECT_FALSE(a == b);
+}
+
+TEST(OptionalTest, Equals_TwoDifferent) {
+  Optional<int> a(0);
+  Optional<int> b(1);
+
+  EXPECT_FALSE(a == b);
+}
+
+TEST(OptionalTest, NotEquals_TwoEmpty) {
+  Optional<int> a;
+  Optional<int> b;
+
+  EXPECT_FALSE(a != b);
+}
+
+TEST(OptionalTest, NotEquals_TwoEquals) {
+  Optional<int> a(1);
+  Optional<int> b(1);
+
+  EXPECT_FALSE(a != b);
+}
+
+TEST(OptionalTest, NotEquals_OneEmpty) {
+  Optional<int> a;
+  Optional<int> b(1);
+
+  EXPECT_TRUE(a != b);
+}
+
+TEST(OptionalTest, NotEquals_TwoDifferent) {
+  Optional<int> a(0);
+  Optional<int> b(1);
+
+  EXPECT_TRUE(a != b);
+}
+
+TEST(OptionalTest, Less_LeftEmpty) {
+  Optional<int> l;
+  Optional<int> r(1);
+
+  EXPECT_TRUE(l < r);
+}
+
+TEST(OptionalTest, Less_RightEmpty) {
+  Optional<int> l(1);
+  Optional<int> r;
+
+  EXPECT_FALSE(l < r);
+}
+
+TEST(OptionalTest, Less_BothEmpty) {
+  Optional<int> l;
+  Optional<int> r;
+
+  EXPECT_FALSE(l < r);
+}
+
+TEST(OptionalTest, Less_BothValues) {
+  {
+    Optional<int> l(1);
+    Optional<int> r(2);
+
+    EXPECT_TRUE(l < r);
+  }
+  {
+    Optional<int> l(2);
+    Optional<int> r(1);
+
+    EXPECT_FALSE(l < r);
+  }
+  {
+    Optional<int> l(1);
+    Optional<int> r(1);
+
+    EXPECT_FALSE(l < r);
+  }
+}
+
+TEST(OptionalTest, LessEq_LeftEmpty) {
+  Optional<int> l;
+  Optional<int> r(1);
+
+  EXPECT_TRUE(l <= r);
+}
+
+TEST(OptionalTest, LessEq_RightEmpty) {
+  Optional<int> l(1);
+  Optional<int> r;
+
+  EXPECT_FALSE(l <= r);
+}
+
+TEST(OptionalTest, LessEq_BothEmpty) {
+  Optional<int> l;
+  Optional<int> r;
+
+  EXPECT_TRUE(l <= r);
+}
+
+TEST(OptionalTest, LessEq_BothValues) {
+  {
+    Optional<int> l(1);
+    Optional<int> r(2);
+
+    EXPECT_TRUE(l <= r);
+  }
+  {
+    Optional<int> l(2);
+    Optional<int> r(1);
+
+    EXPECT_FALSE(l <= r);
+  }
+  {
+    Optional<int> l(1);
+    Optional<int> r(1);
+
+    EXPECT_TRUE(l <= r);
+  }
+}
+
+TEST(OptionalTest, Greater_BothEmpty) {
+  Optional<int> l;
+  Optional<int> r;
+
+  EXPECT_FALSE(l > r);
+}
+
+TEST(OptionalTest, Greater_LeftEmpty) {
+  Optional<int> l;
+  Optional<int> r(1);
+
+  EXPECT_FALSE(l > r);
+}
+
+TEST(OptionalTest, Greater_RightEmpty) {
+  Optional<int> l(1);
+  Optional<int> r;
+
+  EXPECT_TRUE(l > r);
+}
+
+TEST(OptionalTest, Greater_BothValue) {
+  {
+    Optional<int> l(1);
+    Optional<int> r(2);
+
+    EXPECT_FALSE(l > r);
+  }
+  {
+    Optional<int> l(2);
+    Optional<int> r(1);
+
+    EXPECT_TRUE(l > r);
+  }
+  {
+    Optional<int> l(1);
+    Optional<int> r(1);
+
+    EXPECT_FALSE(l > r);
+  }
+}
+
+TEST(OptionalTest, GreaterEq_BothEmpty) {
+  Optional<int> l;
+  Optional<int> r;
+
+  EXPECT_TRUE(l >= r);
+}
+
+TEST(OptionalTest, GreaterEq_LeftEmpty) {
+  Optional<int> l;
+  Optional<int> r(1);
+
+  EXPECT_FALSE(l >= r);
+}
+
+TEST(OptionalTest, GreaterEq_RightEmpty) {
+  Optional<int> l(1);
+  Optional<int> r;
+
+  EXPECT_TRUE(l >= r);
+}
+
+TEST(OptionalTest, GreaterEq_BothValue) {
+  {
+    Optional<int> l(1);
+    Optional<int> r(2);
+
+    EXPECT_FALSE(l >= r);
+  }
+  {
+    Optional<int> l(2);
+    Optional<int> r(1);
+
+    EXPECT_TRUE(l >= r);
+  }
+  {
+    Optional<int> l(1);
+    Optional<int> r(1);
+
+    EXPECT_TRUE(l >= r);
+  }
+}
+
+TEST(OptionalTest, OptNullEq) {
+  {
+    Optional<int> opt;
+    EXPECT_TRUE(opt == base::nullopt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_FALSE(opt == base::nullopt);
+  }
+}
+
+TEST(OptionalTest, NullOptEq) {
+  {
+    Optional<int> opt;
+    EXPECT_TRUE(base::nullopt == opt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_FALSE(base::nullopt == opt);
+  }
+}
+
+TEST(OptionalTest, OptNullNotEq) {
+  {
+    Optional<int> opt;
+    EXPECT_FALSE(opt != base::nullopt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_TRUE(opt != base::nullopt);
+  }
+}
+
+TEST(OptionalTest, NullOptNotEq) {
+  {
+    Optional<int> opt;
+    EXPECT_FALSE(base::nullopt != opt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_TRUE(base::nullopt != opt);
+  }
+}
+
+TEST(OptionalTest, OptNullLower) {
+  {
+    Optional<int> opt;
+    EXPECT_FALSE(opt < base::nullopt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_FALSE(opt < base::nullopt);
+  }
+}
+
+TEST(OptionalTest, NullOptLower) {
+  {
+    Optional<int> opt;
+    EXPECT_FALSE(base::nullopt < opt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_TRUE(base::nullopt < opt);
+  }
+}
+
+TEST(OptionalTest, OptNullLowerEq) {
+  {
+    Optional<int> opt;
+    EXPECT_TRUE(opt <= base::nullopt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_FALSE(opt <= base::nullopt);
+  }
+}
+
+TEST(OptionalTest, NullOptLowerEq) {
+  {
+    Optional<int> opt;
+    EXPECT_TRUE(base::nullopt <= opt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_TRUE(base::nullopt <= opt);
+  }
+}
+
+TEST(OptionalTest, OptNullGreater) {
+  {
+    Optional<int> opt;
+    EXPECT_FALSE(opt > base::nullopt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_TRUE(opt > base::nullopt);
+  }
+}
+
+TEST(OptionalTest, NullOptGreater) {
+  {
+    Optional<int> opt;
+    EXPECT_FALSE(base::nullopt > opt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_FALSE(base::nullopt > opt);
+  }
+}
+
+TEST(OptionalTest, OptNullGreaterEq) {
+  {
+    Optional<int> opt;
+    EXPECT_TRUE(opt >= base::nullopt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_TRUE(opt >= base::nullopt);
+  }
+}
+
+TEST(OptionalTest, NullOptGreaterEq) {
+  {
+    Optional<int> opt;
+    EXPECT_TRUE(base::nullopt >= opt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_FALSE(base::nullopt >= opt);
+  }
+}
+
+TEST(OptionalTest, ValueEq_Empty) {
+  Optional<int> opt;
+  EXPECT_FALSE(opt == 1);
+}
+
+TEST(OptionalTest, ValueEq_NotEmpty) {
+  {
+    Optional<int> opt(0);
+    EXPECT_FALSE(opt == 1);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_TRUE(opt == 1);
+  }
+}
+
+TEST(OptionalTest, EqValue_Empty) {
+  Optional<int> opt;
+  EXPECT_FALSE(1 == opt);
+}
+
+TEST(OptionalTest, EqValue_NotEmpty) {
+  {
+    Optional<int> opt(0);
+    EXPECT_FALSE(1 == opt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_TRUE(1 == opt);
+  }
+}
+
+TEST(OptionalTest, ValueNotEq_Empty) {
+  Optional<int> opt;
+  EXPECT_TRUE(opt != 1);
+}
+
+TEST(OptionalTest, ValueNotEq_NotEmpty) {
+  {
+    Optional<int> opt(0);
+    EXPECT_TRUE(opt != 1);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_FALSE(opt != 1);
+  }
+}
+
+TEST(OptionalTest, NotEqValue_Empty) {
+  Optional<int> opt;
+  EXPECT_TRUE(1 != opt);
+}
+
+TEST(OptionalTest, NotEqValue_NotEmpty) {
+  {
+    Optional<int> opt(0);
+    EXPECT_TRUE(1 != opt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_FALSE(1 != opt);
+  }
+}
+
+TEST(OptionalTest, ValueLess_Empty) {
+  Optional<int> opt;
+  EXPECT_TRUE(opt < 1);
+}
+
+TEST(OptionalTest, ValueLess_NotEmpty) {
+  {
+    Optional<int> opt(0);
+    EXPECT_TRUE(opt < 1);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_FALSE(opt < 1);
+  }
+  {
+    Optional<int> opt(2);
+    EXPECT_FALSE(opt < 1);
+  }
+}
+
+TEST(OptionalTest, LessValue_Empty) {
+  Optional<int> opt;
+  EXPECT_FALSE(1 < opt);
+}
+
+TEST(OptionalTest, LessValue_NotEmpty) {
+  {
+    Optional<int> opt(0);
+    EXPECT_FALSE(1 < opt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_FALSE(1 < opt);
+  }
+  {
+    Optional<int> opt(2);
+    EXPECT_TRUE(1 < opt);
+  }
+}
+
+TEST(OptionalTest, ValueLessEq_Empty) {
+  Optional<int> opt;
+  EXPECT_TRUE(opt <= 1);
+}
+
+TEST(OptionalTest, ValueLessEq_NotEmpty) {
+  {
+    Optional<int> opt(0);
+    EXPECT_TRUE(opt <= 1);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_TRUE(opt <= 1);
+  }
+  {
+    Optional<int> opt(2);
+    EXPECT_FALSE(opt <= 1);
+  }
+}
+
+TEST(OptionalTest, LessEqValue_Empty) {
+  Optional<int> opt;
+  EXPECT_FALSE(1 <= opt);
+}
+
+TEST(OptionalTest, LessEqValue_NotEmpty) {
+  {
+    Optional<int> opt(0);
+    EXPECT_FALSE(1 <= opt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_TRUE(1 <= opt);
+  }
+  {
+    Optional<int> opt(2);
+    EXPECT_TRUE(1 <= opt);
+  }
+}
+
+TEST(OptionalTest, ValueGreater_Empty) {
+  Optional<int> opt;
+  EXPECT_FALSE(opt > 1);
+}
+
+TEST(OptionalTest, ValueGreater_NotEmpty) {
+  {
+    Optional<int> opt(0);
+    EXPECT_FALSE(opt > 1);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_FALSE(opt > 1);
+  }
+  {
+    Optional<int> opt(2);
+    EXPECT_TRUE(opt > 1);
+  }
+}
+
+TEST(OptionalTest, GreaterValue_Empty) {
+  Optional<int> opt;
+  EXPECT_TRUE(1 > opt);
+}
+
+TEST(OptionalTest, GreaterValue_NotEmpty) {
+  {
+    Optional<int> opt(0);
+    EXPECT_TRUE(1 > opt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_FALSE(1 > opt);
+  }
+  {
+    Optional<int> opt(2);
+    EXPECT_FALSE(1 > opt);
+  }
+}
+
+TEST(OptionalTest, ValueGreaterEq_Empty) {
+  Optional<int> opt;
+  EXPECT_FALSE(opt >= 1);
+}
+
+TEST(OptionalTest, ValueGreaterEq_NotEmpty) {
+  {
+    Optional<int> opt(0);
+    EXPECT_FALSE(opt >= 1);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_TRUE(opt >= 1);
+  }
+  {
+    Optional<int> opt(2);
+    EXPECT_TRUE(opt >= 1);
+  }
+}
+
+TEST(OptionalTest, GreaterEqValue_Empty) {
+  Optional<int> opt;
+  EXPECT_TRUE(1 >= opt);
+}
+
+TEST(OptionalTest, GreaterEqValue_NotEmpty) {
+  {
+    Optional<int> opt(0);
+    EXPECT_TRUE(1 >= opt);
+  }
+  {
+    Optional<int> opt(1);
+    EXPECT_TRUE(1 >= opt);
+  }
+  {
+    Optional<int> opt(2);
+    EXPECT_FALSE(1 >= opt);
+  }
+}
+
+TEST(OptionalTest, NotEquals) {
+  {
+    Optional<float> a(0.1f);
+    Optional<float> b(0.2f);
+    EXPECT_NE(a, b);
+  }
+
+  {
+    Optional<std::string> a("foo");
+    Optional<std::string> b("bar");
+    EXPECT_NE(a, b);
+  }
+
+  {
+    Optional<TestObject> a(TestObject(3, 0.1));
+    Optional<TestObject> b(TestObject(4, 1.0));
+    EXPECT_TRUE(a != b);
+  }
+}
+
+TEST(OptionalTest, NotEqualsNull) {
+  {
+    Optional<float> a(0.1f);
+    Optional<float> b(0.1f);
+    b = base::nullopt;
+    EXPECT_NE(a, b);
+  }
+
+  {
+    Optional<std::string> a("foo");
+    Optional<std::string> b("foo");
+    b = base::nullopt;
+    EXPECT_NE(a, b);
+  }
+
+  {
+    Optional<TestObject> a(TestObject(3, 0.1));
+    Optional<TestObject> b(TestObject(3, 0.1));
+    b = base::nullopt;
+    EXPECT_TRUE(a != b);
+  }
+}
+
+TEST(OptionalTest, MakeOptional) {
+  {
+    Optional<float> o = base::make_optional(32.f);
+    EXPECT_TRUE(o);
+    EXPECT_EQ(32.f, *o);
+
+    float value = 3.f;
+    o = base::make_optional(std::move(value));
+    EXPECT_TRUE(o);
+    EXPECT_EQ(3.f, *o);
+  }
+
+  {
+    Optional<const char*> o = base::make_optional("foo");
+    EXPECT_TRUE(o);
+    EXPECT_EQ("foo", *o);
+
+    const char* value = "bar";
+    o = base::make_optional(std::move(value));
+    EXPECT_TRUE(o);
+    EXPECT_EQ("bar", *o);
+  }
+
+  {
+    Optional<TestObject> o = base::make_optional(TestObject(3, 0.1));
+    EXPECT_TRUE(!!o);
+    EXPECT_TRUE(TestObject(3, 0.1) == *o);
+
+    TestObject value = TestObject(0, 0.42);
+    o = base::make_optional(std::move(value));
+    EXPECT_TRUE(!!o);
+    EXPECT_TRUE(TestObject(0, 0.42) == *o);
+    EXPECT_EQ(TestObject::State::MOVED_FROM, value.state());
+    EXPECT_EQ(TestObject::State::COPY_CONSTRUCTED, o->state());
+
+    EXPECT_EQ(TestObject::State::MOVE_CONSTRUCTED,
+              base::make_optional(std::move(value))->state());
+  }
+}
+
+TEST(OptionalTest, NonMemberSwap_bothNoValue) {
+  Optional<TestObject> a, b;
+  base::swap(a, b);
+
+  EXPECT_FALSE(!!a);
+  EXPECT_FALSE(!!b);
+  EXPECT_TRUE(TestObject(42, 0.42) == a.value_or(TestObject(42, 0.42)));
+  EXPECT_TRUE(TestObject(42, 0.42) == b.value_or(TestObject(42, 0.42)));
+}
+
+TEST(OptionalTest, NonMemberSwap_inHasValue) {
+  Optional<TestObject> a(TestObject(1, 0.3));
+  Optional<TestObject> b;
+  base::swap(a, b);
+
+  EXPECT_FALSE(!!a);
+  EXPECT_TRUE(!!b);
+  EXPECT_TRUE(TestObject(42, 0.42) == a.value_or(TestObject(42, 0.42)));
+  EXPECT_TRUE(TestObject(1, 0.3) == b.value_or(TestObject(42, 0.42)));
+}
+
+TEST(OptionalTest, NonMemberSwap_outHasValue) {
+  Optional<TestObject> a;
+  Optional<TestObject> b(TestObject(1, 0.3));
+  base::swap(a, b);
+
+  EXPECT_TRUE(!!a);
+  EXPECT_FALSE(!!b);
+  EXPECT_TRUE(TestObject(1, 0.3) == a.value_or(TestObject(42, 0.42)));
+  EXPECT_TRUE(TestObject(42, 0.42) == b.value_or(TestObject(42, 0.42)));
+}
+
+TEST(OptionalTest, NonMemberSwap_bothValue) {
+  Optional<TestObject> a(TestObject(0, 0.1));
+  Optional<TestObject> b(TestObject(1, 0.3));
+  base::swap(a, b);
+
+  EXPECT_TRUE(!!a);
+  EXPECT_TRUE(!!b);
+  EXPECT_TRUE(TestObject(1, 0.3) == a.value_or(TestObject(42, 0.42)));
+  EXPECT_TRUE(TestObject(0, 0.1) == b.value_or(TestObject(42, 0.42)));
+}
+
+TEST(OptionalTest, Hash_OptionalReflectsInternal) {
+  {
+    std::hash<int> int_hash;
+    std::hash<Optional<int>> opt_int_hash;
+
+    EXPECT_EQ(int_hash(1), opt_int_hash(Optional<int>(1)));
+  }
+
+  {
+    std::hash<std::string> str_hash;
+    std::hash<Optional<std::string>> opt_str_hash;
+
+    EXPECT_EQ(str_hash(std::string("foobar")),
+              opt_str_hash(Optional<std::string>(std::string("foobar"))));
+  }
+}
+
+TEST(OptionalTest, Hash_NullOptEqualsNullOpt) {
+  std::hash<Optional<int>> opt_int_hash;
+  std::hash<Optional<std::string>> opt_str_hash;
+
+  EXPECT_EQ(opt_str_hash(Optional<std::string>()),
+            opt_int_hash(Optional<int>()));
+}
+
+TEST(OptionalTest, Hash_UseInSet) {
+  std::set<Optional<int>> setOptInt;
+
+  EXPECT_EQ(setOptInt.end(), setOptInt.find(42));
+
+  setOptInt.insert(Optional<int>(3));
+  EXPECT_EQ(setOptInt.end(), setOptInt.find(42));
+  EXPECT_NE(setOptInt.end(), setOptInt.find(3));
+}
+
+}  // namespace base