unit test for inputParser output matlab

Question

I am just beginning to dive into testing in Matlab, and I am trying to write a test which will check whether inputParser is properly catching incorrect function argument values. For example:

function [imageNamesForImport] = imageFileSearch(fileList, stringToMatch)

iP = inputParser;
iP.addRequired('fileList', @isstruct);
iP.addRequired('stringToMatch', @ischar);
iP.parse(fileList, stringToMatch);

will throw an error if I pass a variable as fileList which is not a structure

fileList = 'foo'
stringToMatch = 'bar'
imageNamesForImport = imageFileSearch(fileList, stringToMatch)

Error using imageFileSearch (line 7)
The value of 'fileList' is invalid. It must satisfy the function: isstruct.

Is it possible to write a unit test to check for this output without having to use a series of try / catch statements to assign custom errors for verifyError?

Answer 1

You could set up your own unit testing framework and use a single try-catch block inside of a for loop:

% Set up test cases
test(1).fileList = 'foo';
test(2).fileList.a = 12;
test(3).fileList.a = 'bar';

test(1).stringToMatch = 'bar';
test(2).stringToMatch = 5;
test(3).stringToMatch = 'bar';

% Run tests
myerrs = [];
for ii = 1:length(test)
    try
        imageNamesForImport = imageFileSearch(test(ii).fileList, test(ii).stringToMatch);
    catch err
        myerrs = [myerrs err];
        % Any other custom things here
    end
end

Which in this case gives us a 1x2 structure of errors that we can investigate.

---

You could also utilize MATLAB's Unit Testing Framework. Here's a simple example for a Script-Based Unit Test:

imageFileSearch.m

function [imageNamesForImport] = imageFileSearch(fileList, stringToMatch)

iP = inputParser;
iP.addRequired('fileList', @isstruct);
iP.addRequired('stringToMatch', @ischar);
iP.parse(fileList, stringToMatch);
imageNamesForImport = 'hi';

testtrial.m

%% Test 1
fileList = 'foo';
stringToMatch = 'bar';
imageNamesForImport = imageFileSearch(fileList, stringToMatch);

%% Test 2
fileList.a = 12;
stringToMatch = 5;
imageNamesForImport = imageFileSearch(fileList, stringToMatch);

%% Test 3
fileList.a = 'bar';
stringToMatch = 'bar';
imageNamesForImport = imageFileSearch(fileList, stringToMatch);

Which gives us the following command window output:

Running testtrial

================================================================================
Error occurred in testtrial/Test1 and it did not run to completion.

    --------------
    Error Details:
    --------------
    The value of 'fileList' is invalid. It must satisfy the function: isstruct.

================================================================================
.
================================================================================
Error occurred in testtrial/Test2 and it did not run to completion.

    --------------
    Error Details:
    --------------
    The value of 'stringToMatch' is invalid. It must satisfy the function: ischar.

================================================================================
..
Done testtrial
__________

Failure Summary:

     Name             Failed  Incomplete  Reason(s)
    ================================================
     testtrial/Test1    X         X       Errored.
    ------------------------------------------------
     testtrial/Test2    X         X       Errored.