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matlabunit-testing
Michael A
Michael A

Reputation: 4613

Why does MATLAB's unit testing method verifyEqual fail when two numerically identical objects have different classes?

I'm using the unit testing framework in MATLAB and I noticed something weird. In this example:

classdef MyTest < matlab.unittest.TestCase
    methods (Test)
        function testEqual(testCase)
            x = [1:3 7:8];
            y = 1:5;
            resultLogical = x == y;
            resultDouble = [1 1 1 0 0];
            assert(isequal(resultLogical, resultDouble), 'not equal')
            verifyEqual(testCase, resultLogical, resultDouble)
        end
    end
end

When I run this with results = run(MyTest);, the unit test fails in the verifyEqual statement because resultLogical and resultDouble have different classes, even though the assert statement is successful because isequal understands that both objects are numeric equivalents.

Is there a way around this? I find myself constantly writing

verifyTrue(testCase, isequal(resultLogical, resultDouble))

when I need to compare two arrays of different types. Is this the only way? I don't see any of the qualifications that would work better than this, unfortunately.

Upvotes: 3

Views: 999

Answers (1)

Andy Campbell
Andy Campbell

Reputation: 2187

verifyEqual is more strict than isequal because this is usually the desired behavior when automated testing. If you are testing an algorithm that accepts an int8 and should then return an int8, providing the expected value as an int8 will catch the bug that can occur if the algorithm incorrectly returns a double. This strictness also applies to other attributes of the value such as its sparsity, complexity, and size.

In your case, if you do not care about the class of the object then you can cast the actual value to the type of the expected value such as:

verifyEqual(testCase, double(resultLogical), resultDouble);

This will result in better diagnostics than using verifyTrue. Hope that helps!

Upvotes: 4

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