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verifyFail

Class: matlab.unittest.qualifications.Verifiable
Package: matlab.unittest.qualifications

Produce unconditional verification failure

Syntax

verifyFail(verifiable)
verifyFail(verifiable,diagnostic)

Description

verifyFail(verifiable) produces an unconditional verification failure when encountered.

verifyFail(verifiable,diagnostic) also associates the diagnostic information in diagnostic with the qualification. Depending on the test runner configuration, the testing framework might display diagnostics when the qualification passes or fails. By default, the framework displays diagnostics only when the qualification fails. You can override the default behavior by customizing the test runner. For example, use a DiagnosticsOutputPlugin instance to display both failing and passing event diagnostics.

Input Arguments

verifiable

The matlab.unittest.TestCase instance which is used to pass or fail the verification in conjunction with the test running framework.

diagnostic

Diagnostic information related to the qualification, specified as one of the following:

  • string array

  • character array

  • function handle

  • matlab.unittest.diagnostics.Diagnostic object

Diagnostic values can be nonscalar. For more information, see matlab.unittest.diagnostics.Diagnostic.

Examples

expand all

An example of where this method may be used is in a callback function that should not be executed in a given scenario. A test can confirm this does not occur by unconditionally performing a failure if the code path is reached.

Create a handle class, MyHandle, with a SomethingHappened event.

classdef MyHandle < handle
    events
        SomethingHappened
    end
end

Create a file, ListenerTest, on your MATLAB® path that contains the following TestCase class.

classdef ListenerTest < matlab.unittest.TestCase
    methods(Test)
        function testDisabledListeners(testCase)
            h = MyHandle;
            
            % Add a listener to a test helper method
            listener = h.addlistener('SomethingHappened', ...
                @testCase.shouldNotGetCalled);
            
            % Passing scenario (code path is not reached)
            %%%%%%%%%%%%%%%%%%%%
            % Disabled listener should not invoke callbacks
            listener.Enabled = false;
            h.notify('SomethingHappened');
            
            % Failing scenario (code path is reached)
            %%%%%%%%%%%%%%%%%%%%
            % Enabled listener invoke callback and fail
            listener.Enabled = true;
            h.notify('SomethingHappened');
        end
    end
    
    methods
        function shouldNotGetCalled(testCase, ~, ~)
            % A test helper callback method that should not execute
            testCase.verifyFail('This listener callback should not have executed');
        end
    end
    
end

From the command prompt, run the test.

run(ListenerTest);
Running ListenerTest

================================================================================
Verification failed in ListenerTest/testDisabledListeners.

    ----------------
    Test Diagnostic:
    ----------------
    This listener callback should not have executed

    ------------------
    Stack Information:
    ------------------
    In C:\Desktop\ListenerTest.m (ListenerTest.shouldNotGetCalled) at 27
    In C:\\Desktop\ListenerTest.m (@(varargin)testCase.shouldNotGetCalled(varargin{:})) at 8
    In C:\Desktop\ListenerTest.m (ListenerTest.testDisabledListeners) at 20
================================================================================
.
Done ListenerTest
__________

Failure Summary:

     Name                                Failed  Incomplete  Reason(s)
    =================================================================================
     ListenerTest/testDisabledListeners    X                 Failed by verification.

Tips

  • Use verification qualifications to produce and record failures without throwing an exception. Since verifications do not throw exceptions, all test content runs to completion even when verification failures occur. Typically verifications are the primary qualification for a unit test since they typically do not require an early exit from the test. Use other qualification types to test for violation of preconditions or incorrect test setup. Alternatively,

    • Use assumption qualifications to ensure that the test environment meets preconditions that otherwise do not result in a test failure. Assumption failures result in filtered tests, and the testing framework marks the tests as Incomplete. For more information, see matlab.unittest.qualifications.Assumable.

    • Use assertion qualifications when the failure condition invalidates the remainder of the current test content, but does not prevent proper execution of subsequent test methods. A failure at the assertion point renders the current test method as failed and incomplete. For more information, see matlab.unittest.qualifications.Assertable.

    • Use fatal assertion qualifications to abort the test session upon failure. These qualifications are useful when the failure mode is so fundamental that there is no point in continuing testing. These qualifications are also useful when fixture teardown does not restore the MATLAB state correctly and it is preferable to abort testing and start a fresh session. For more information, see matlab.unittest.qualifications.FatalAssertable.

Introduced in R2013a