feat(app): add graceful shutdown support to MessageQueue

tests/app/message_queue_test.cpp

@@ -17,8 +17,9 @@ void testPushAndPop() {
 
   auto message = queue.pop();
 
-  assert(message.level == logger::LogLevel::info());
-  assert(message.message == "Hello");
+  assert(message.has_value());
+  assert(message->level == logger::LogLevel::info());
+  assert(message->message == "Hello");
 }
 
 void testFifoOrder() {
@@ -28,9 +29,9 @@ void testFifoOrder() {
   queue.push({logger::LogLevel::info(), "second"});
   queue.push({logger::LogLevel::error(), "third"});
 
-  assert(queue.pop().message == "first");
-  assert(queue.pop().message == "second");
-  assert(queue.pop().message == "third");
+  assert(queue.pop()->message == "first");
+  assert(queue.pop()->message == "second");
+  assert(queue.pop()->message == "third");
 }
 
 void testPopWaitsForMessage() {
@@ -41,8 +42,9 @@ void testPopWaitsForMessage() {
   std::thread worker([&]() {
     auto message = queue.pop();
 
-    assert(message.level == logger::LogLevel::error());
-    assert(message.message == "Delayed");
+    assert(message.has_value());
+    assert(message->level == logger::LogLevel::error());
+    assert(message->message == "Delayed");
 
     received = true;
   });
@@ -74,12 +76,14 @@ void testConcurrentPushAndPop() {
     producers.emplace_back(
         helpers::createProducer(queue, i, messagesPerThread));
   }
+
   const auto expectedMessages = threadCount * messagesPerThread;
 
   for (std::size_t i = 0; i < expectedMessages; ++i) {
     auto message = queue.pop();
 
-    assert(!message.message.empty());
+    assert(message.has_value());
+    assert(!message->message.empty());
   }
 
   for (auto &producer : producers) {
@@ -89,11 +93,44 @@ void testConcurrentPushAndPop() {
   assert(queue.empty());
 }
 
+void testStopReturnsNullopt() {
+  MessageQueue queue;
+
+  queue.stop();
+
+  auto message = queue.pop();
+
+  assert(!message.has_value());
+}
+
+void testStopReturnsRemainingMessages() {
+  MessageQueue queue;
+
+  queue.push({logger::LogLevel::info(), "first"});
+  queue.push({logger::LogLevel::error(), "second"});
+
+  queue.stop();
+
+  auto first = queue.pop();
+  auto second = queue.pop();
+  auto third = queue.pop();
+
+  assert(first.has_value());
+  assert(first->message == "first");
+
+  assert(second.has_value());
+  assert(second->message == "second");
+
+  assert(!third.has_value());
+}
+
 void runTests() {
   testPushAndPop();
   testFifoOrder();
   testPopWaitsForMessage();
   testConcurrentPushAndPop();
+  testStopReturnsNullopt();
+  testStopReturnsRemainingMessages();
 }
 
 } // namespace app::tests