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verifyReturnsTrue

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

Verify function returns true when evaluated

Syntax

verifyReturnsTrue(verifiable,actual)
verifyReturnsTrue(___,diagnostic)

Description

verifyReturnsTrue(verifiable,actual) verifies that actual is a function handle that returns a scalar logical whose value is true.

verifyReturnsTrue(___,diagnostic) also displays the diagnostic information in diagnostic upon a failure.

Input Arguments

verifiable

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

actual

The function handle to test.

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

Create a TestCase object for interactive testing.

testCase = matlab.unittest.TestCase.forInteractiveUse;
verifyReturnsTrue(testCase, @true);
Interactive verification passed.

Verify that it is true that two numbers are equal.

verifyReturnsTrue(testCase, @() isequal(1,1));
Interactive verification passed.

Verify that it is true that two letters are not the same.

verifyReturnsTrue(testCase, @() ~strcmp('a','b'));
Interactive verification passed.

Cause verification to fail by trying to verify that “false” evaluates to “true”.

verifyReturnsTrue(testCase, @false);
Interactive verification failed.

---------------------
Framework Diagnostic:
---------------------
verifyReturnsTrue failed.
--> The function handle should have evaluated to "true".
--> Returned value:
             0

Actual Function Handle:
        @false

Test failed.

Cause verification to fail by having the test specified in the function handle return a vector of logical values not a scalar logical value.

verifyReturnsTrue(testCase, @() strcmp('a',{'a','a'}));
Interactive verification failed.

---------------------
Framework Diagnostic:
---------------------
verifyReturnsTrue failed.
--> The function handle should have returned a scalar. The return value had a size of [1  2].
--> Returned value:
             1     1

Actual Function Handle:
        @()strcmp('a',{'a','a'})

Test failed.

Cause verification to fail by having the test specified in the function handle return a double not a logical.

verifyReturnsTrue(testCase, @() exist('exist'));
Interactive verification failed.

---------------------
Framework Diagnostic:
---------------------
verifyReturnsTrue failed.
--> The function handle should have returned a logical value. It was of type "double".
--> Returned value:
             5

Actual Function Handle:
        @()exist('exist')

Test failed.

Tips

  • It is a shortcut for quick custom comparison functionality that can be defined quickly, and possibly inline. It can be preferable over simply evaluating the function directly and using verifyTrue because the function handle will be shown in the diagnostics, thus providing more insight into the failure condition which is lost when using verifyTrue.

  • This method is functionally equivalent to:

    import matlab.unittest.constraints.ReturnsTrue;
    verifiable.verifyThat(actual, ReturnsTrue());
    

    There exists more functionality when using the ReturnsTrue constraint directly via verifyThat.

  • 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