Fix flaky test timing out sometimes while waiting for data

The test used to hang on waitForRead(), sometimes, which underneath
involve a poll()+read() syscall pair.
When this happened, the IMAP data came together with the proxy data on a
previous poll()+read() call and the proxy code had already consumed it.

We now wait for data only if data is not already available.

Fixes: QTBUG-96345
Pick-to: 6.2
Change-Id: I084f5d1268a5091ea614fcec91c8d356dcb90d9f
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 7 insertions, 4 deletions

diff --git a/tests/auto/network/socket/qsocks5socketengine/tst_qsocks5socketengine.cpp b/tests/auto/network/socket/qsocks5socketengine/tst_qsocks5socketengine.cpp
index 7bf057cd5a..11e17cb319 100644
--- a/tests/auto/network/socket/qsocks5socketengine/tst_qsocks5socketengine.cpp
+++ b/tests/auto/network/socket/qsocks5socketengine/tst_qsocks5socketengine.cpp
@@ -312,12 +312,15 @@ void tst_QSocks5SocketEngine::simpleConnectToIMAP()
     QCOMPARE(socketDevice.state(), QAbstractSocket::ConnectedState);
     QCOMPARE(socketDevice.peerAddress(), QtNetworkSettings::imapServerIp());
 
-    // Wait for the greeting
-    QVERIFY2(socketDevice.waitForRead(), qPrintable("Socket error:" + socketDevice.errorString()));
-
-    // Read the greeting
+    // Wait for the greeting, if it hasn't arrived yet
     qint64 available = socketDevice.bytesAvailable();
+    if (available == 0) {
+        QVERIFY2(socketDevice.waitForRead(), qPrintable("Socket error:" + socketDevice.errorString()));
+        available = socketDevice.bytesAvailable();
+    }
     QVERIFY(available > 0);
+
+    // Read the greeting
     QByteArray array;
     array.resize(available);
     QVERIFY(socketDevice.read(array.data(), array.size()) == available);