How to make a mocked object property observable without superclass?

Question

Ralf Ritter 2022-2-3

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1642060-how-to-make-a-mocked-object-property-observable-without-superclass

回答： Gayatri 2024-1-30

I need to test a class which listents for property changes of another object, for example

classdef MyClass
    methods
        function obj = MyClass(observedObject)
            addlistener(observedObject, 'propertyA', 'PostSet', @obj.doSomething);            
        end
    end
end

In order to test MyClass, I would create a mock for observedObject to inject into the constructor of MyClass, like

observedObjectMock = tc.createMock(?handle, 'AddedProperties', "propertyA");
myObject = MyClass(observedObjectMock);

However, this is not allowed and I recieve the following error message:

While adding a PostSet listener, property 'propertyA' in class 'matlab.mock.classes.handleMock' is not defined to be SetObservable.

I know that this can be fixed by creating a superclass for observedObject which has an observable abstract propertyA:

classdef ObservableSuperClass < handle
    properties (Abstract, SetObservable)
        propertyA
    end
end
% Mock would then be created like this
observedObjectMock = tc.createMock(?ObservableSuperClass);

Is there a way to make this work using Matlab's Mocking Framework without having to create an extra superclass?

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Answer 1

Gayatri 2024-1-30

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https://ww2.mathworks.cn/matlabcentral/answers/1642060-how-to-make-a-mocked-object-property-observable-without-superclass#answer_1399546

Hi,

It seems that you are encountering an error while adding a “PostSet” listener: property “propertyA” in class “matlab.mock.classes.handleMock” is not defined to be “SetObservable”.

When creating a mock object for testing in MATLAB, ensure that the properties you want to listen to are observable.

This is because the MATLAB mocking framework requires that the properties of the object being mocked have the “SetObservable” attribute if you intend to add a “PostSet” listener to them.

There is no direct way to add the “SetObservable” attribute to a property in a mock object without defining it in a superclass.

The approach of creating a superclass with the “SetObservable” attribute is the correct way to ensure that the property is observable in the mock.

I hope this helps!