1 files changed, 200 insertions, 0 deletions
diff --git a/mfbt/tests/gtest/TestInitializedOnce.cpp b/mfbt/tests/gtest/TestInitializedOnce.cpp
new file mode 100644
index 0000000000..a043013451
--- /dev/null
+++ b/mfbt/tests/gtest/TestInitializedOnce.cpp
@@ -0,0 +1,200 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "gtest/gtest.h"
+
+#include "mozilla/InitializedOnce.h"
+
+#include <type_traits>
+
+using namespace mozilla;
+
+namespace {
+template <typename T>
+void AssertIsSome(const T& aVal) {
+  ASSERT_TRUE(aVal);
+  ASSERT_TRUE(aVal.isSome());
+  ASSERT_FALSE(aVal.isNothing());
+}
+
+template <typename T>
+void AssertIsNothing(const T& aVal) {
+  ASSERT_FALSE(aVal);
+  ASSERT_FALSE(aVal.isSome());
+  ASSERT_TRUE(aVal.isNothing());
+}
+
+static_assert(std::is_trivially_destructible_v<InitializedOnce<const int>>);
+static_assert(std::is_trivially_destructible_v<LazyInitializedOnce<const int>>);
+
+static_assert(!std::is_copy_constructible_v<InitializedOnce<const int>>);
+static_assert(!std::is_copy_assignable_v<InitializedOnce<const int>>);
+
+static_assert(!std::is_default_constructible_v<InitializedOnce<const int>>);
+static_assert(std::is_default_constructible_v<LazyInitializedOnce<const int>>);
+static_assert(std::is_default_constructible_v<
+              LazyInitializedOnceEarlyDestructible<const int>>);
+
+// XXX We cannot test for move-constructability/move-assignability at the
+// moment, since the operations are always defined, but trigger static_assert's
+// if they should not be used. This is not too bad, since we are never copyable.
+
+constexpr InitializedOnce<const int>* kPtrInitializedOnceIntLazyInitForbid =
+    nullptr;
+constexpr LazyInitializedOnce<const int>* kPtrInitializedOnceIntLazyInitAllow =
+    nullptr;
+constexpr LazyInitializedOnceEarlyDestructible<const int>*
+    kPtrInitializedOnceIntLazyInitAllowResettable = nullptr;
+
+template <class T, typename = decltype(std::declval<T*>()->destroy())>
+constexpr bool test_has_destroy_method(const T*) {
+  return true;
+}
+constexpr bool test_has_destroy_method(...) { return false; }
+
+static_assert(test_has_destroy_method(kPtrInitializedOnceIntLazyInitForbid));
+static_assert(!test_has_destroy_method(kPtrInitializedOnceIntLazyInitAllow));
+static_assert(
+    test_has_destroy_method(kPtrInitializedOnceIntLazyInitAllowResettable));
+
+template <class T,
+          typename = decltype(std::declval<T*>()->init(std::declval<int>()))>
+constexpr bool test_has_init_method(const T*) {
+  return true;
+}
+constexpr bool test_has_init_method(...) { return false; }
+
+static_assert(!test_has_init_method(kPtrInitializedOnceIntLazyInitForbid));
+static_assert(test_has_init_method(kPtrInitializedOnceIntLazyInitAllow));
+static_assert(
+    test_has_init_method(kPtrInitializedOnceIntLazyInitAllowResettable));
+
+struct MoveOnly {
+  explicit constexpr MoveOnly(int aValue) : mValue{aValue} {}
+
+  MoveOnly(MoveOnly&&) = default;
+  MoveOnly& operator=(MoveOnly&&) = default;
+
+  int mValue;
+};
+
+}  // namespace
+
+constexpr int testValue = 32;
+
+TEST(InitializedOnce, ImmediateInit)
+{
+  constexpr InitializedOnce<const MoveOnly> val{testValue};
+
+  // compile-time assertions
+  static_assert(val);
+  static_assert(val.isSome());
+  static_assert(!val.isNothing());
+  static_assert(testValue == (*val).mValue);
+  static_assert(testValue == val->mValue);
+  static_assert(testValue == val.ref().mValue);
+
+  // run-time assertions
+  AssertIsSome(val);
+  ASSERT_EQ(testValue, (*val).mValue);
+  ASSERT_EQ(testValue, val->mValue);
+  ASSERT_EQ(testValue, val.ref().mValue);
+}
+
+TEST(InitializedOnce, ImmediateInitReset)
+{
+  InitializedOnce<const MoveOnly> val{testValue};
+  val.destroy();
+
+  AssertIsNothing(val);
+}
+
+TEST(InitializedOnce, MoveConstruct)
+{
+  InitializedOnce<const MoveOnly> oldVal{testValue};
+  InitializedOnce<const MoveOnly> val{std::move(oldVal)};
+
+  AssertIsNothing(oldVal);
+  AssertIsSome(val);
+}
+
+TEST(InitializedOnceAllowLazy, DefaultCtor)
+{
+  LazyInitializedOnce<const MoveOnly> val;
+
+  AssertIsNothing(val);
+}
+
+TEST(InitializedOnceAllowLazy, Init)
+{
+  LazyInitializedOnce<const MoveOnly> val;
+  val.init(testValue);
+
+  AssertIsSome(val);
+  ASSERT_EQ(testValue, (*val).mValue);
+  ASSERT_EQ(testValue, val->mValue);
+  ASSERT_EQ(testValue, val.ref().mValue);
+}
+
+TEST(InitializedOnceAllowLazy, do_Init)
+{
+  LazyInitializedOnce<const MoveOnly> val;
+  do_Init(val) = MoveOnly{testValue};
+
+  AssertIsSome(val);
+  ASSERT_EQ(testValue, (*val).mValue);
+  ASSERT_EQ(testValue, val->mValue);
+  ASSERT_EQ(testValue, val.ref().mValue);
+}
+
+TEST(InitializedOnceAllowLazyResettable, DefaultCtor)
+{
+  LazyInitializedOnceEarlyDestructible<const MoveOnly> val;
+
+  AssertIsNothing(val);
+}
+
+TEST(InitializedOnceAllowLazyResettable, Init)
+{
+  LazyInitializedOnceEarlyDestructible<const MoveOnly> val;
+  val.init(testValue);
+
+  AssertIsSome(val);
+  ASSERT_EQ(testValue, (*val).mValue);
+  ASSERT_EQ(testValue, val->mValue);
+  ASSERT_EQ(testValue, val.ref().mValue);
+}
+
+TEST(InitializedOnceAllowLazyResettable, InitReset)
+{
+  LazyInitializedOnceEarlyDestructible<const MoveOnly> val;
+  val.init(testValue);
+  val.destroy();
+
+  AssertIsNothing(val);
+}
+
+TEST(InitializedOnceAllowLazyResettable, MoveConstruct)
+{
+  LazyInitializedOnceEarlyDestructible<const MoveOnly> oldVal{testValue};
+  LazyInitializedOnceEarlyDestructible<const MoveOnly> val{std::move(oldVal)};
+
+  AssertIsNothing(oldVal);
+  AssertIsSome(val);
+}
+
+TEST(InitializedOnceAllowLazyResettable, MoveAssign)
+{
+  LazyInitializedOnceEarlyDestructible<const MoveOnly> oldVal{testValue};
+  LazyInitializedOnceEarlyDestructible<const MoveOnly> val;
+
+  val = std::move(oldVal);
+
+  AssertIsNothing(oldVal);
+  AssertIsSome(val);
+}
+
+// XXX How do we test for assertions to be hit?