🐛 Empty address creates QHostAddress::Any like in Qt5 (#10)

The behavior changed in Qt6, a `QHostAddress("")` now create a
`QHostAddress::Any` in qt5 & qt6.
This is how I'm using this library, so I expected that as part of the
public API behavior.

src/Server.cpp

@@ -201,7 +201,8 @@ bool Server::startWorker()
     clear();
 
     // Start to listen
-    const auto result = _worker->listen(QHostAddress(address()), port());
+    const auto hostAddress = address().isEmpty() ? QHostAddress::Any : QHostAddress(address());
+    const auto result = _worker->listen(hostAddress, port());
     setListening(result);
     return result;
 }

tests/ServerTests.cpp

@@ -38,11 +38,11 @@ class ServerTests : public ::testing::Test
 
     QTimer timer;
 
-    void echoTest(quint16 port)
+    void echoTest(quint16 port, QString serverAddress = "127.0.0.1")
     {
         QSignalSpy connectedSpy(&client, &MySocket::isConnectedChanged);
         client.start("127.0.0.1", port);
-        server.start("127.0.0.1", port);
+        server.start(serverAddress, port);
         if(!client.isConnected())
         {
             ASSERT_TRUE(connectedSpy.wait());
@@ -120,6 +120,23 @@ class ServerTests : public ::testing::Test
     }
 };
 
+TEST_F(ServerTests, echoTestEmptyServerHostAddress)
+{
+    server.setUseWorkerThread(false);
+    client.setUseWorkerThread(false);
+    // Empty QString -> QHostAddress is creating a QHostAddress::Any in Qt5, but QHostAddress::Null in Qt6
+    // We want to keep the behavior of Qt5
+    echoTest(30000, "");
+}
+
+TEST_F(ServerTests, echoTest0000ServerHostAddress)
+{
+    server.setUseWorkerThread(false);
+    client.setUseWorkerThread(false);
+    // This should create a QHostAddress::Any
+    echoTest(30000, "0.0.0.0");
+}
+
 TEST_F(ServerTests, echoTestMonoThread)
 {
     server.setUseWorkerThread(false);