What is the difference between the SetupGet() and Setup() methods for MOQ?
Setup() can be used for mocking a method or a property.
SetupGet() is specifically for mocking the getter of a property. Took a quick peek at the Moq source code and it looks like if you use Setup() on a property getter, it will call SetupGet(). So in that case, it is probably more personal preference as to whether you want to be more explicit and use SetupGet() instead of Setup().
Of course, my knowledge of Moq is limited, so I don't know if there special cases where you would need to use SetupGet() over Setup().
SetupGet works when you're trying to mock read only property
Related
A simple question regarding the new signal/slot syntax in Qt5:
Are there still benefits for a Q_OBJECT-derived class to have public slots: sections declared?
Note: With the new syntax you're able to connect a signal to any public function of a class or directly implement a C++11 lambda (which can also call some member functions itself).
Qt's new signal/slot syntax
While the answers by vahancho and TheDarkKnight are valid: slots is not required for connections, but it makes the intent clearer and allows introspection. I think I should list some use cases where you do need slots.
First please note that you can use slots, Q_SLOTS, Q_SLOT or Q_INVOKABLE to make a function known to the meta object (introspection) system. Q_INVOKABLE has the advantage that it can be used on constructors.
And here are the use cases in no particular order:
Make your code works with Qt 4. Even if Qt 4 is not maintained I think some big company are still using it and it is fairly easy to make a library works with Qt 5 and Qt 4.
Make the function available in QML (and Qt Quick)
Make the function available in javascript (Qt Script, Qt WebEngine, etc.)
Make the function callable with QMetaObject::invokeMethod(). An overload that accepts functors will be available in Qt 5.10.
Make use of QMetaObject::connectSlotsByName(). Note that this function should not be used as it can be affected by object name collisions, but it is still the way the Qt widget designer connects the slots it creates.
Make your class instantiatable with QMetaObject::newInstance().
And every other use case that requires run-time introspection
you're able to connect a signal to any public function of a class or directly implement a C++11 lambda
Whilst this was made available in Qt 5, which allows for compile-time verification of the slot, as opposed to when using the SIGNAL and SLOT macros, it is no longer a requirement to declare a function as a slot to connect to it.
However, for clarity I still do, as it makes the intention of a class clearer for usage, when others come to using the class.
For example:
class Foo : public QObject
{
public:
Foo();
public slots:
void AddData();
private:
void CalculateStuff();
};
Just by looking at the class, we can assume that the function AddData is designed to be called via a signal; perhaps it executes on a separate thread.
public slots: etc. declarations still needed for moc introspection if you are going to use the "old" connection style. With the new syntax this declarations do not make any sense, because, as you also noticed, "slots" are called directly by function pointers. "Slots" may even be a non class member functions as well.
However, you still need to declare your signals under signals: section of your class declaration.
They're still needed for Qml, so that you can connect to C++ slots. However, if you want to call a C++ QObject member function, you can just declare it as Q_INVOKABLE. You don't need to make it a slot. Although using slots: might be more readable compared to using Q_INVOKABLE. Up to you.
They're also needed if you want Designer to see them. Designer has a "signal/slot" editor, and it will not list functions that are not in the slots: section. However, Designer still uses the old string-based syntax for signals and slots, so I wouldn't recommend using its signal/slot editor.
I am currently using following pattern when creating tests with QTest.
One test class per production class.
If a class has some 'global' setting run the test class multiple times with each such setting.
Each production class method has one test method.
Each test method has _data method.
Each _data method specify settings and data to be used and names the cases.
This last point somewhat bothers me because I am not passing just data but also data to be used for initialising that particular test. Sometimes it looks weird and even though my tests are short they are not all that intuitive because of the initialisation logic.
The alternative pattern I know of is to split each test method (breaking my rule #3) based on this initialisation needs. On one hand it would eliminate a lot of _data test methods but it would also make the test classes much bigger and no longer easily relatable to the production class (the naming would help though). Most google tests are written like this.
Another alternative would be to use global state of the object much like I treat global settings. If the object is either valid or invalid then it would not be part of each _data method but rather setting of the test class that would run in either configuration.
My main concern is maintainability. With my current approach I sometimes struggle to understand the nuances of the settings I pass to the tests and I need some sensible way to separate them and not to burden myself even more by it.
For global settings you run the test class multiple times, so IMHO doing the same for local settings doesn't really "violate" your rule #3, it is more an extension of rule #2.
Alternatively you could make the initialization routine another thing that is part of the test data.
Something like
private slots:
void someMethodTest_data()
{
QTest::addColumn<QByteArray>("settings");
//....
QTest::addRow("case1") << "settings1" << ....
}
void someMethodTest()
{
Q_FETCH(QByteArray, settings);
const QByteArray initMethod = QTest::currentTestFuntion() + "_init_" + settings;
QMetaObject::invokeMethod(this, initMethod.constData(), Qt::DirectConnect);
// commence test
}
protected slots:
void someMethodTest_init_settings1();
I'm a beginner in Qt and trying to understand the SIGNAL and SLOT macros. When I'm learning to use the connect method to bind the signal and slot, I found the tutorials on Qt's official reference page uses:
connect(obj1, SIGNAL(signal(int)), obj2, SLOT(slot()))
However, this also works very well:
connect(obj1, &Obj1::signal, obj2, &Obj2::slot)
So what exactly do the macros SIGNAL and SLOT do? Do they just look for the signal in the class the object belongs to and return the address of it?
Then why do most programmers use these macros instead of using &Obj1::signal since the latter appears to be simpler and you don't need to change the code if the parameters of the signal function change?
The use of the SIGNAL and SLOT macros used to be the only way to make connections, before Qt 5. The connection is made at runtime and require signal and slots to be marked in the header. For example:
Class MyClass : public QObject
{
Q_OBJECT
signals:
void Signal();
slots:
void ASlotFunction();
};
To avoid repetition, the way in which it works is described in the QT 4 documentation.
The signal and slot mechanism is part of the C++ extensions that are provided by Qt and make use of the Meta Object Compiler (moc).
This explains why signals and slots use the moc.
The second connect method is much improved as the functions specified can be checked at the time of compilation, not runtime. In addition, by using the address of a function, you can refer to any class function, not just those in the section marked slots:
The documentation was updated for Qt 5.
In addition, there's a good blog post about the Qt 4 connect workings here and Qt 5 here.
Addition to the first answer.
what exactly did the macro SIGNAL and SLOT do
Almost nothing. Look at the qobjectdefs.h:
# define SLOT(a) "1"#a
# define SIGNAL(a) "2"#a
It just adds 1 or 2. It means that next code is valid and works as expected:
QObject *obj = new QObject;
connect(obj,"2objectNameChanged(QString)",this,"1show()");//suppose this is a pointer to a QDialog subclass
obj->setObjectName("newNAme");
why do most programmers use these macros instead of using like
&Obj1::signal
Because these macros work not only in Qt5.
Because with these macros there is no complexity with overloaded
signals (it can make your code very dirty and it is really not a simple thing)
Because with new syntax you sometimes need to use specific
disconnects
More details here.
To complete TheDarkKnight's answer, it is an excellent practice to refactor legacy code that is using the old Qt 4 SIGNAL and SLOT macros to Qt 5's new syntax using function address.
Suddenly, connection error will appear at compile time instead of at runtime! It's very easy to make a Qt 4 connection error as any spelling mistake will result in such an error. Plus, the name of the function must be the fully qualified name, i.e preceded with the full namespace if any.
Another benefit is the ability to use a lambda for the slot function, which can reduce need of a named function if the slot body is trivial.
These macros just convert their parameters to signal/slot-specific strings. The Differences between String-Based and Functor-Based Connections can be found in the docs. In short:
String-based:
Type checking is done at Run-time
Can connect signals to slots which have more arguments than the signal (using default parameters)
Can connect C++ functions to QML functions
Functor-based:
Type checking is done at Compile-time
Can perform implicit type conversions
Can connect signals to lambda expressions
So what I am trying to do is use Qt signals and slots to pass around an image through a smart_ptr so that it will delete itself when everything that needs to use the data is done accessing it.
Here is the code I have:
Class A, inherits QObject:
signals:
void newImageSent(boost::shared_ptr<namespace::ImageData> &image);
Class B, inherits QObject:
public slots:
void newImageRecieved(boost::shared_ptr<namespace::ImageData> &image)
{
// Manipulate Image
}
Connection Code:
QObject::connect(classAPtr.get(),
SIGNAL(newImageSent(boost::shared_ptr<namespace::ImageData>)),
classBPtr.get(),
SLOT(newImageRecieved(boost::shared_ptr<namespace::ImageData>)),
Qt::QueuedConnection);
When I try to do the connection is always returns false though, so is there something I am missing?
In a queued connection the signal is queued in the event loop and its parameters are copied.
Therefore the slot is not directly executed.
To make copying possible you have to register the type via qRegisterMetaType, see also here.
Since you are using shared pointers easiest solution would be to transmit them by value, then you would not have to bother with the references as Frank Osterfeld pointed out.
The way you create the connection is string based and as result is easy to get wrong, especially when namespaces are involved.
Using typedef would ease the pain a little and make it easier to spot errors.
For example you could do
typedef boost::shared_ptr<namespace::ImageData> ImageDataPtr;
and use ImageDataPtr from then on.
Especially on registering the type as meta type which you have to do since you are using a queued connection.
If you are using Qt5 then you can rely on the new connection syntax which ensures correctness during compilation as it does not rely on string comparisons:
QObject::connect(classAPtr.get(), &A::newImageSent,
classBPtr.get(), &B::newImageRecieved,
Qt::QueuedConnection);
Qt4.8.5
QObject::connect(button,SIGNAL(clicked()),label,SLOT(setText("dd"));
The Qt Creator tell me It's wrong . What's the problem ?
That you can't pass arguments in a connect() statement. You need a "trampoline" slot that sets the text of your label (or, in Qt 5, you might choose to use a lambda).
For instance, by using a subclass:
class MyLabel : public QLabel {
Q_OBJECT
public slots:
void setTextToFoo() { setText("foo"); }
};
// ...
connect(button,SIGNAL(clicked()),label,SLOT(setTextToFoo());
It depends what exactly you are trying to achieve, to be honest, the example code you provided is not very functional, is "dd" a particular static value you are using, or potentially some other string? Where does it come from, is it in the scope of the called, or is it sent by the caller, which is the usual practice when sending arguments to slots.
Either way, in order to make a connect statement the first requirement is for the arguments to match, clicked() has no arguments while setText() has one, so there is a mismatch. As of how to resolve that mismatch, the easiest way is to use simple wrappers, although you can use a QSignalMapper and as of Qt5, lambdas and std::bind.
For starters, you cannot specify the actual argument instance in the connect statement, even with arguments on both sides you only need to specify the types to help resolve overloads (it is terrible with the new connection syntax in Qt5), and not any actual identifiers or literals.
In case of the more usual scenario, where the data is send to the slot by the caller, the identifier or literal is specified in the emit signal(value) statement. Since you don't have clicked(const QString &) you need a wrapper slot that you connect to clicked() and emit with the value in that wrapper slot, or subclass the button and add your own overload of clicked(QString).
In case the value is in the scope of the called, then subclassing doesn't make much sense, all you need is the wrapper slot in the scope of the called object.
If you want more, you will have to use Qt 5, whose syntax is significantly more powerful.
If the question is whats wrong, just remember the parameter number must be the same for the Signal and the Slot. Asking a collegue and according the Peppe, setText(QString) wait for One parameter and the Clicked() is empty...A custom slot is to call the setText() method indirectly.
You can look that : http://qt-project.org/doc/qt-4.8/widgets-calculator.html
It uses the QWidget, an important part of Qt interfaces beside QML.