tst_qbluetoothdevicediscoveryagent to reliably pass on Android

Android backend is sometimes unable to cancel the device discovery
right after issuing the stop(). The Qt backend code is prepared for
this and instead does a pending cancel (cancels later) and emits an
error. Based on testing this happens sometimes on an Android 10 device,
and often on an Android 12 device.

This behavior difference causes the autotest to fail and this commit
introduces a small delay between start() and stop() to remove this
behavioral difference. Notably this commit does not accommodate the
potential behavior difference because the test function itself would
become unreasonably complex.

As a drive-by simplify the wait loops and convert numeric QVERIFYs
to QCOMPAREs to give the actual number if something failed.

Pick-to: 6.2 6.3
Change-Id: Iae3d0ebfaae59660af80bed906da5098e4b899d1
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Andreas Buhr <andreas.buhr@qt.io>

1 files changed, 42 insertions, 27 deletions

diff --git a/tests/auto/qbluetoothdevicediscoveryagent/tst_qbluetoothdevicediscoveryagent.cpp b/tests/auto/qbluetoothdevicediscoveryagent/tst_qbluetoothdevicediscoveryagent.cpp
index a8202b9e..2437ab85 100644
--- a/tests/auto/qbluetoothdevicediscoveryagent/tst_qbluetoothdevicediscoveryagent.cpp
+++ b/tests/auto/qbluetoothdevicediscoveryagent/tst_qbluetoothdevicediscoveryagent.cpp
@@ -55,6 +55,11 @@ const int MaxScanTime = 5 * 60 * 1000;  // 5 minutes in ms
 //Bluez needs at least 10s for a device discovery to be cancelled
 const int MaxWaitForCancelTime = 15 * 1000;  // 15 seconds in ms
 
+#ifdef Q_OS_ANDROID
+// Android is sometimes unable to cancel immediately
+const int WaitBeforeStopTime = 200;
+#endif
+
 class tst_QBluetoothDeviceDiscoveryAgent : public QObject
 {
     Q_OBJECT
@@ -178,14 +183,22 @@ void tst_QBluetoothDeviceDiscoveryAgent::tst_startStopDeviceDiscoveries()
         QSKIP("No local Bluetooth device available. Skipping remaining part of test.");
     }
     // cancel current request.
+#ifdef Q_OS_ANDROID
+    // Android sometimes can't cancel immediately (~on the same millisecond),
+    // but instead a "pending cancel" happens, which means the discovery will be
+    // canceled at a later point in time. When this happens the Android backend
+    // also emits an immediate errorOccurred(). While this seems to be as intended,
+    // as a result many parts of this test function may fail (not always).
+    //
+    // In this test function we wait some milliseconds between start() and stop() to
+    // bypass this behavior difference. This is to avoid complex iffery (Android itself
+    // can behave differently every time) and ifdeffery (Q_OS_ANDROID) in the test
+    QTest::qWait(WaitBeforeStopTime);
+#endif
     discoveryAgent.stop();
 
     // Wait for up to MaxWaitForCancelTime for the cancel to finish
-    int waitTime = MaxWaitForCancelTime;
-    while (cancelSpy.isEmpty() && waitTime > 0) {
-        QTest::qWait(100);
-        waitTime-=100;
-    }
+    QTRY_VERIFY_WITH_TIMEOUT(!cancelSpy.isEmpty(), MaxWaitForCancelTime);
 
     // we should not be active anymore
     QVERIFY(!discoveryAgent.isActive());
@@ -202,19 +215,19 @@ void tst_QBluetoothDeviceDiscoveryAgent::tst_startStopDeviceDiscoveries()
     QVERIFY(discoveryAgent.isActive());
     QVERIFY(errorSpy.isEmpty());
     // stop
+#ifdef Q_OS_ANDROID
+    QTest::qWait(WaitBeforeStopTime);
+#endif
     discoveryAgent.stop();
 
     // Wait for up to MaxWaitForCancelTime for the cancel to finish
-    waitTime = MaxWaitForCancelTime;
-    while (cancelSpy.isEmpty() && waitTime > 0) {
-        QTest::qWait(100);
-        waitTime-=100;
-    }
+    QTRY_VERIFY_WITH_TIMEOUT(!cancelSpy.isEmpty(), MaxWaitForCancelTime);
 
     // we should not be active anymore
     QVERIFY(!discoveryAgent.isActive());
     QVERIFY(errorSpy.isEmpty());
-    QVERIFY(cancelSpy.size() == 1);
+
+    QCOMPARE(cancelSpy.size(), 1);
     cancelSpy.clear();
 
     //  Starting case 3: stop
@@ -244,6 +257,9 @@ void tst_QBluetoothDeviceDiscoveryAgent::tst_startStopDeviceDiscoveries()
     QVERIFY(discoveryAgent.isActive());
     QVERIFY(errorSpy.isEmpty());
     // cancel current request.
+#ifdef Q_OS_ANDROID
+    QTest::qWait(WaitBeforeStopTime);
+#endif
     discoveryAgent.stop();
     //should only have triggered cancel() if stop didn't involve the event loop
     if (cancelSpy.size() == 1) immediateSignal = true;
@@ -254,25 +270,25 @@ void tst_QBluetoothDeviceDiscoveryAgent::tst_startStopDeviceDiscoveries()
     QVERIFY(discoveryAgent.isActive());
     QVERIFY(errorSpy.isEmpty());
     // stop
+#ifdef Q_OS_ANDROID
+    QTest::qWait(WaitBeforeStopTime);
+#endif
     discoveryAgent.stop();
     if (immediateSignal)
-        QVERIFY(cancelSpy.size() == 2);
+        QCOMPARE(cancelSpy.size(), 2);
 
     // Wait for up to MaxWaitForCancelTime for the cancel to finish
-    waitTime = MaxWaitForCancelTime;
-    while (cancelSpy.isEmpty() && waitTime > 0) {
-        QTest::qWait(100);
-        waitTime-=100;
-    }
+    QTRY_VERIFY_WITH_TIMEOUT(!cancelSpy.isEmpty(), MaxWaitForCancelTime);
+
     // we should not be active anymore
     QVERIFY(!discoveryAgent.isActive());
     QVERIFY(errorSpy.isEmpty());
-    // should only have 1 cancel
 
+    // should only have 1 cancel
     if (immediateSignal)
-        QVERIFY(cancelSpy.size() == 2);
+        QCOMPARE(cancelSpy.size(), 2);
     else
-        QVERIFY(cancelSpy.size() == 1);
+        QCOMPARE(cancelSpy.size(), 1);
     cancelSpy.clear();
 
     // Starting case 5: start-stop-start: expecting finished signal & no cancel
@@ -280,6 +296,9 @@ void tst_QBluetoothDeviceDiscoveryAgent::tst_startStopDeviceDiscoveries()
     QVERIFY(discoveryAgent.isActive());
     QVERIFY(errorSpy.isEmpty());
     // cancel current request.
+#ifdef Q_OS_ANDROID
+    QTest::qWait(WaitBeforeStopTime);
+#endif
     discoveryAgent.stop();
     // start a new one
     discoveryAgent.start();
@@ -287,18 +306,14 @@ void tst_QBluetoothDeviceDiscoveryAgent::tst_startStopDeviceDiscoveries()
     QVERIFY(discoveryAgent.isActive());
     QVERIFY(errorSpy.isEmpty());
 
-    // Wait for up to MaxScanTime for the cancel to finish
-    waitTime = MaxScanTime;
-    while (finishedSpy.isEmpty() && waitTime > 0) {
-        QTest::qWait(1000);
-        waitTime-=1000;
-    }
+    // Wait for up to MaxScanTime for the scan to finish
+    QTRY_VERIFY_WITH_TIMEOUT(!finishedSpy.isEmpty(), MaxScanTime);
 
     // we should not be active anymore
     QVERIFY(!discoveryAgent.isActive());
     QVERIFY(errorSpy.isEmpty());
     // should only have 1 cancel
-    QVERIFY(finishedSpy.size() == 1);
+    QCOMPARE(finishedSpy.size(), 1);
 
     // On OS X, stop is synchronous (signal will be emitted immediately).
     if (!immediateSignal)