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POQObject double deletion
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copied!<p>I am currently running Qt 4.7.4 on Mac OS X 10.6. I installed Qt using MacPorts.</p> <p>I have been trying to use test-driven development as a part of my coding practice, and I am using QtTest for this purpose. I have a class derived from QObject, and when I try to test the code, my test fails when it should pass. I looked at the output of (test -vs), and I observe the following error:</p> <blockquote> <p>INFO : periodictable::ElementTest::testName() Signal: QObject(7fff5fbfd860) destroyed ((QObject*)7fff5fbfd860)</p> </blockquote> <p>In a test case, I observe the above error twice, sandwiching the actual test. This indicates that the child object is destroyed before usage and seemingly deleted again after the test. I have used QPointer and confirmed that the object becomes invalid before usage. The alternative is to initialize the variables within each test case, thus defeating the purpose of a single-shot initialization and in turn, increasing code bloat.</p> <pre><code>class Element : public QObject { Q_OBJECT Q_PROPERTY(QString name READ name WRITE setName NOTIFY valueChanged) public: Element(QObject* parent = 0) : QObject(parent) {} void setName(const QString& name); QString name() const; Q_SIGNALS: void valueChanged(QString value); private: QString elementName; Q_DISABLE_COPY(Element); }; </code></pre> <p>I use the following command (via cmake):</p> <blockquote> <p>g++ -D_FORTIFY_SOURCE=2 -D_GLIBCXX_FULLY_DYNAMIC_STRING -D_FORTIFY_SOURCE=2 -DQT_TEST_LIB -DQT_CORE_LIB -DQT_DEBUG -Wformat-security -Wmissing-format-attribute -Wformat=2 -Wctor-dtor-privacy -Wabi -Woverloaded-virtual -Wsign-promo -Wformat-nonliteral -Wdisabled-optimization -Wformat-y2k -Winit-self -Winvalid-pch -Wunsafe-loop-optimizations -Wmissing-format-attribute -Wmissing-include-dirs -Wstrict-aliasing=3 -Wswitch-enum -Wvariadic-macros -Wvolatile-register-var -std=gnu++0x -fmessage-length=0 -ftree-vectorize --param max-unroll-times=4 -pipe -fabi-version=4 -g -I/opt/local/include/QtCore -fPIC -fstack-protector -fPIC -fstack-protector -Wstack-protector</p> </blockquote> <p>I cannot recall experiencing this problem with Qt 4.6, and I am confused as to the premature destruction.</p> <p>I would like to think that this is not a bug within Qt, but I am curious if anyone else had encountered such a problem and found a solution. I like Qt, but this problem will not be limited to the unit tests. Any help will be certainly appreciated.</p> <p>-- Edit --</p> <p>Source code for test case:</p> <p>in .h file</p> <pre><code>#ifndef TEST_ELEMENT_H #define TEST_ELEMENT_H #include <QtCore/QObject> #include <QtCore/QPointer> namespace hashtable { class Element; // Forward declaration class ElementTest : public QObject { Q_OBJECT private Q_SLOTS: void initTestCase(); void testName(); private: QString name; QPointer<Element> element; }; } #endif </code></pre> <p>in .cpp file</p> <pre><code>void ElementTest::initTestCase() { name = QString("Hydrogen"); mass = 1.008; QPointer<Element> element(new Element(this)); return; } void ElementTest::testName() { element->setProperty("name", name); QCOMPARE(element->property("name").toString(), name); } </code></pre>

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