How to change property behavior for a mocked object

19 views (last 30 days)
TADA
TADA on 25 Jun 2019
Commented: TADA on 19 Aug 2019
I'm trying to use the mocking framework for unit tests
I'm trying to make the property of a mock object return another mock object, but the behavior object doesn't have the property
classdef MyClass
properties (GetAccess=public, SetAccess=protected)
prop1;
end
methods
function this = answer()
end
end
end
this is the mock decleration:
testCase = matlab.mock.TestCase.forInteractiveUse;
[mock,behav] = testCase.createMock(?MyClass);
% this would obciously throw an exception because the property set method is protected
mock.prop1 = "";
You cannot set the read-only property 'prop1' of MyClassMock.
% this throws an exception because the behavior object doesn't have this property
p = behav.prop1;
No appropriate method, property, or field 'prop1' for class 'matlab.mock.classes.MyClassBehavior'.
now i can't set the value of the mock object because the set access is protected
and i can't use the behavior object to change the property behavior because I can't find the propertyBehavior thing anywhere
I'm obviously missing something, but all the examples I've seen in the documentation show how to use a custom mock object with "AddedProperties"
and I could be tackling this the wrong way, but I prefer to create the mock object using the meta class

Accepted Answer

M Wells
M Wells on 15 Aug 2019
Edited: M Wells on 15 Aug 2019
Mock objects are still a recent feature of MATLAB and I don't think they are practical for testing classes yet. There are still quite a few features that are lacking for sufficiantly replicating object behaviour, for instance having a mock object method call assign a value to a protected property.
The solution to the above case is to create your mock without using the meta-class instance:
testCase = matlab.mock.TestCase.forInteractiveUse;
[MyClassMock, behaviour] = createMock(testCase, 'AddedProperties', "prop1", 'AddedMethods', "answer")
testCase.assignOutputsWhen(get(behaviour.prop1), 'abc')
p = MyClassMock.prop1
It's not ideal but I don't think there's any other option at this time. You can still test for access violations this way:
import matlab.mock.actions.ThrowException
when(set(behaviour.prop1),...
ThrowException(MException('MATLAB:class:SetProhibited',...
'You cannot set the read-only property ''prop1'' of MyClass.')))
Creating a mock from a meta-class only works for classes with abstract properties and methods.
  2 Comments
TADA
TADA on 19 Aug 2019
So apparently, it is enough to override isa for matlab to pass property type validations
[mock, mb] = createMock(testCase, 'AddedProperties', "prop1", 'AddedMethods', ["answer", "isa"])
testCase.assignOutputsWhen(mb.isa('MyClass'),true)
So I might do that after all

Sign in to comment.

More Answers (0)

Products


Release

R2018b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!