MATLAB Grader: What should my assessment return when it determines a student solution is correct or incorrect?

Let's say the assignment is to create (and leave open) a figure with three subplots and one of the subplots should have the title "Oscillating Motion". I want to use an assessment of Test Type MATLAB Code to check the figure the student's code has created. I can easily check that using Matlab code similar to the following

% Get the handles of all subplots
axis_handles = findobj(gcf, 'type', 'axes');
% see if the title matches the requirement
set_required_title = false;
for axnum=1:length(axis_handles)
    title_str = get(get(axis_handles(axnum),'Title'),'String');
    set_required_title = set_required_title | strcmpi(title_str,'Oscillating Motion');
end

How do I return that result (the variable set_required_title) as an assessment test?

BTW, just for context of what I am talking about, in my LMS, this looks like

Answer 1

[Dyuman Joshi]

You can use assert to check a condition (whether the title contains a particular text or not) and throw a (custom defined) error (like the one you have written - with subplot number added if you want to provide a specific error) when the condition is not satisfied.

[M. E. Brokowski]

I think that is exactly what I needed to know. If the assesment script asserts an error, then the test failed.

Thank you very much for that.

And, of course, now that I know what I am looking for, I can see that the documentation (https://www.mathworks.com/help/matlabgrader/ug/assessments-for-script-based-learner-solutions.html) mentions that. It would be helpful if it gave an example.

[Dyuman Joshi]

Check this - https://in.mathworks.com/help/matlabgrader/ug/assessments-for-script-based-learner-solutions.html#mw_37e9b2e8-6d13-4b98-b363-31e97cd5ea2b

[M. E. Brokowski]

Isn't that the same page I posted before? I was saying it would be improved by an example showing the use of assert() as an example of an assessment test.

[Dyuman Joshi]

It's linked to that page, yes.

As for on example, you can check the documentation page of assert, but thpse are not in the context of use in MATLAB Grader.

I can help you write one, if you could copy and paste the code you have posted in the image.

[M. E. Brokowski]

Thanks, but I don't need any help writing the code. Cheers.

Answer 2

[Cris LaPierre]

Please see this Answer: https://www.mathworks.com/matlabcentral/answers/548631-matlab-grader-determining-if-a-variable-is-a-function-handle#answer_451644

Your assessment must return an error if the answer is incorrect. Otherwise, it is considered correct. This is what assert, as well as the built-in assessment functions do.

[Cris LaPierre]

Since you are grading a plot, I suggest also looking at this answer. It shows how to build a more robust custom assessment test so that students alway receive meaningful feedback.

https://www.mathworks.com/matlabcentral/answers/1701790-how-to-check-plot-properties-for-multiple-lines-in-one-plot-grader#answer_947775

[M. E. Brokowski]

Interesting. I had figured out how to check various things in the learner's figure. But, I did not know that the reference plot is closed/unavailable when the assessment test script runs.