What are some ways to mock 'system' for unit testing?

I need to mock returns from calls to 'system' for the purpose of unit testing. I tried overloading the built-in by creating a 'system.m' function that lives in the same folder as my unit tests but the testing framework called foul on that approach and skips the tests that use it:

Warning: Function system has the same name as a MATLAB built-in. We suggest you rename the function to avoid a potential name conflict. 
> In matlab.unittest.TestSuite>temporarilyChangeFolderIfNeeded (line 881)
In matlab.unittest.TestSuite.fromFileCore_ (line 694)
In matlab.unittest.TestSuite.fromFile (line 178)
In matlab.unittest.internal.testbrowser/AlertHandler/callFunctionAndHandleAlerts
In matlab.unittest.internal.testbrowser/SuiteFromFileForTestImport/execute
In matlab.unittest.internal.testbrowser/TestModelService/loadTestFile
In matlab.unittest.internal.testbrowser/TestModelService/loadTestFiles
In matlab.unittest.internal.testbrowser/TestBrowserController/importTestFiles
In matlab.unittest.internal.testbrowser.TestBrowserActionsService.importFilesInJavaDesktop 

One approach is to create a wrapper method for 'system' in the class under test, then create a wrapper class that inherits 'myClass' that is used for testing:

class I want to test

classdef myClass
    methods 
        function [status,cmdout]=systemWrapper(varargin)            
            [status,cmdout]=system(varargin)
            % varargout parsing... blah blah
        end
    end
end

mock class called by tests to overload 'systemWrapper'

classdef myClassMocked < myClass
    methods
        function [status,cmdout]=systemWrapper(varargin)            
            [status,cmdout]=systemMock(varargin)
            % varargout parsing... blah blah
        end
    end
end

I think that should work, but it just smells a bit convoluted and seems like there should be a cleaner way to mock 'system' directly.

[dpb]

Never used the testing framework, but it's a warning, not an error, so I would think the first would still function as wanted.

Since in this case you delibertely alias system you could turn off the warning before by using with

[id,msg]=lastwarn;

at command line to get the precise warning id and then

warning('off',id)

before initiating the test. Reinstate the warning state afterwards, of course.

[Chris]

Thanks, @dpb, but the framework actually skips the test; it uses warnings rather than exceptions so the rest of the test suite can finish.

[dpb]

Well, that sucks, doesn't it? It was just a hypothesis, too bad it wasn't the right one.

If somebody doesn't come along with Framework experience and a better idea, I'd recomend to submit this to Mathworks as an official support request at <Product Support Page> for better approach and/or enhancement request to have a way to force the test despite the specific warning; it seems a reasonable use case for why one would really, indeed, want to alias the builtin.