Increase test coverage for the V4 memory manager

This commit adds a small test that exercises a number of code paths
inside qv4mm.cpp which are normally gated via environment variables.

Change-Id: Ibe959387a9b86ce68df258513446d2165fe06ee2
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

src/qml/memory/qv4mm.cpp

@@ -79,9 +79,9 @@ static uint maxShiftValue()
     static uint result = 0;
     if (!result) {
         result = 6;
-        if (Q_UNLIKELY(qEnvironmentVariableIsSet("QV4_MM_MAXBLOCK_SHIFT"))) {
+        if (Q_UNLIKELY(qEnvironmentVariableIsSet(QV4_MM_MAXBLOCK_SHIFT))) {
             bool ok;
-            const uint overrideValue = qgetenv("QV4_MM_MAXBLOCK_SHIFT").toUInt(&ok);
+            const uint overrideValue = qgetenv(QV4_MM_MAXBLOCK_SHIFT).toUInt(&ok);
             if (ok && overrideValue <= 11 && overrideValue > 0)
                 result = overrideValue;
         }
@@ -94,9 +94,9 @@ static std::size_t maxChunkSizeValue()
     static std::size_t result = 0;
     if (!result) {
         result = 32 * 1024;
-        if (Q_UNLIKELY(qEnvironmentVariableIsSet("QV4_MM_MAX_CHUNK_SIZE"))) {
+        if (Q_UNLIKELY(qEnvironmentVariableIsSet(QV4_MM_MAX_CHUNK_SIZE))) {
             bool ok;
-            const std::size_t overrideValue = qgetenv("QV4_MM_MAX_CHUNK_SIZE").toUInt(&ok);
+            const std::size_t overrideValue = qgetenv(QV4_MM_MAX_CHUNK_SIZE).toUInt(&ok);
             if (ok)
                 result = overrideValue;
         }
@@ -170,7 +170,7 @@ struct MemoryManager::Data
         , maxShift(maxShiftValue())
         , gcBlocked(false)
         , aggressiveGC(!qEnvironmentVariableIsEmpty("QV4_MM_AGGRESSIVE_GC"))
-        , gcStats(!qEnvironmentVariableIsEmpty("QV4_MM_STATS"))
+        , gcStats(!qEnvironmentVariableIsEmpty(QV4_MM_STATS))
     {
         memset(nonFullChunks, 0, sizeof(nonFullChunks));
         memset(nChunks, 0, sizeof(nChunks));

src/qml/memory/qv4mm_p.h

@@ -59,6 +59,10 @@
 
 //#define DETAILED_MM_STATS
 
+#define QV4_MM_MAXBLOCK_SHIFT "QV4_MM_MAXBLOCK_SHIFT"
+#define QV4_MM_MAX_CHUNK_SIZE "QV4_MM_MAX_CHUNK_SIZE"
+#define QV4_MM_STATS "QV4_MM_STATS"
+
 QT_BEGIN_NAMESPACE
 
 namespace QV4 {

tests/auto/qml/qml.pro

@@ -62,7 +62,8 @@ PRIVATETESTS += \
     qqmltranslation \
     qqmlimport \
     qqmlobjectmodel \
-    qmldiskcache
+    qmldiskcache \
+    qv4mm
 
 qtHaveModule(widgets) {
     PUBLICTESTS += \

tests/auto/qml/qv4mm/qv4mm.pro

@@ -0,0 +1,8 @@
+CONFIG += testcase
+TARGET = tst_qv4mm
+osx:CONFIG -= app_bundle
+
+SOURCES += tst_qv4mm.cpp
+
+QT += qml qml-private testlib
+

tests/auto/qml/qv4mm/tst_qv4mm.cpp

@@ -0,0 +1,58 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 basysKom GmbH.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <qtest.h>
+#include <QQmlEngine>
+#include <private/qv4mm_p.h>
+
+class tst_qv4mm : public QObject
+{
+    Q_OBJECT
+
+private slots:
+    void gcStats();
+    void tweaks();
+};
+
+void tst_qv4mm::gcStats()
+{
+    qputenv(QV4_MM_STATS, "1");
+    QQmlEngine engine;
+    engine.collectGarbage();
+}
+
+void tst_qv4mm::tweaks()
+{
+    qputenv(QV4_MM_MAXBLOCK_SHIFT, "5");
+    qputenv(QV4_MM_MAX_CHUNK_SIZE, "65536");
+    QQmlEngine engine;
+}
+
+QTEST_MAIN(tst_qv4mm)
+
+#include "tst_qv4mm.moc"