Make inspector animation speed test more robust

We don't exactly know when the animation speed is actually set and the
system clock may play tricks on us. Consider the test failed when the
wrong animation speed is witnessed 3 times in a row and successful if
the correct one is witnessed 3 times in a row. Also, make sure we don't
confuse lines from different hits of the timer.

Task-number: QTBUG-58186
Change-Id: Iaa2c35f723a92f32131e36084399b3d32accb7d0
Reviewed-by: Robin Burchell <robin.burchell@crimson.no>

2 files changed, 37 insertions, 21 deletions

diff --git a/tests/auto/qml/debugger/qqmlinspector/data/qtquick2.qml b/tests/auto/qml/debugger/qqmlinspector/data/qtquick2.qml
index f44c653840..f43cff15e4 100644
--- a/tests/auto/qml/debugger/qqmlinspector/data/qtquick2.qml
+++ b/tests/auto/qml/debugger/qqmlinspector/data/qtquick2.qml
@@ -29,16 +29,15 @@ Rectangle {
             }
 
             var milliDelta = millis - prevHit;
-            if (milliDelta < 0)
+            if (milliDelta <= 0)
                 milliDelta += 1000;
-            console.log(milliDelta, "milliseconds ");
             prevHit = millis;
 
             var delta = parent.rotation - prevRotation;
             if (delta < 0)
                 delta += 360
             prevRotation = parent.rotation
-            console.log(delta, "degrees ");
+            console.log(milliDelta, delta, "ms/degrees ");
         }
     }
 }
diff --git a/tests/auto/qml/debugger/qqmlinspector/tst_qqmlinspector.cpp b/tests/auto/qml/debugger/qqmlinspector/tst_qqmlinspector.cpp
index f55fef232e..9461922eff 100644
--- a/tests/auto/qml/debugger/qqmlinspector/tst_qqmlinspector.cpp
+++ b/tests/auto/qml/debugger/qqmlinspector/tst_qqmlinspector.cpp
@@ -102,29 +102,46 @@ void tst_QQmlInspector::startQmlProcess(const QString &qmlFile, bool restrictSer
 
 void tst_QQmlInspector::checkAnimationSpeed(int targetMillisPerDegree)
 {
-    QString degreesString = QStringLiteral("degrees");
-    QString millisecondsString = QStringLiteral("milliseconds");
-    for (int i = 0; i < 2; ++i) { // skip one period; the change might have happened inside it
-        int position = m_process->output().length();
-        while (!m_process->output().mid(position).contains(degreesString) ||
-               !m_process->output().mid(position).contains(millisecondsString)) {
+    const QString markerString = QStringLiteral("ms/degrees");
+
+    // Funny things can happen with time and VMs. Also the change might take a while to propagate.
+    // Thus, we wait until we either have 3 passes or 3 failures in a row, or 10 loops have passed.
+
+    int numFailures = 0;
+    int numPasses = 0;
+
+    for (int i = 0; i < 10; ++i) {
+        QString output = m_process->output();
+        int position = output.length();
+        do {
             QVERIFY(QQmlDebugTest::waitForSignal(m_process.data(),
                                                  SIGNAL(readyReadStandardOutput())));
+            output = m_process->output();
+        } while (!output.mid(position).contains(markerString));
+
+
+        QStringList words = output.split(QLatin1Char(' '));
+        const int marker = words.lastIndexOf(markerString);
+        QVERIFY(marker > 1);
+        const double degrees = words[marker - 1].toDouble();
+        const int milliseconds = words[marker - 2].toInt();
+        const double millisecondsPerDegree = milliseconds / degrees;
+
+        if (millisecondsPerDegree > targetMillisPerDegree - 3
+                || millisecondsPerDegree < targetMillisPerDegree + 3) {
+            if (++numPasses == 3)
+                return; // pass
+            numFailures = 0;
+        } else {
+            QVERIFY2(++numFailures < 3,
+                     QString("3 consecutive failures when checking for %1 milliseconds per degree")
+                     .arg(targetMillisPerDegree).toLocal8Bit().constData());
+            numPasses = 0;
         }
     }
 
-    QStringList words = m_process->output().split(QLatin1Char(' '));
-    int degreesMarker = words.lastIndexOf(degreesString);
-    QVERIFY(degreesMarker > 1);
-    double degrees = words[degreesMarker - 1].toDouble();
-    int millisecondsMarker = words.lastIndexOf(millisecondsString);
-    QVERIFY(millisecondsMarker > 1);
-    int milliseconds = words[millisecondsMarker - 1].toInt();
-
-    double millisecondsPerDegree = milliseconds / degrees;
-    QVERIFY(millisecondsPerDegree > targetMillisPerDegree - 3);
-    QVERIFY(millisecondsPerDegree < targetMillisPerDegree + 3);
-
+    QFAIL(QString("Animation speed won't settle to %1 milliseconds per degree")
+          .arg(targetMillisPerDegree).toLocal8Bit().constData());
 }
 
 void tst_QQmlInspector::cleanup()