Class: matlab.unittest.qualifications.Assertable
Package: matlab.unittest.qualifications

Assert function returns true when evaluated




assertReturnsTrue(assertable,actual) asserts that actual is a function handle that returns a scalar logical whose value is true.

assertReturnsTrue(assertable,actual,diagnostic) also displays the diagnostic information in diagnostic upon a failure.

Input Arguments


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


The function handle to test.


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.


See examples for verifyReturnsTrue, and replace calls to verifyReturnsTrue with assertReturnsTrue.


  • 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 assertTrue because the function handle will be shown in the diagnostics, thus providing more insight into the failure condition which is lost when using assertTrue.

  • This method is functionally equivalent to:

    import matlab.unittest.constraints.ReturnsTrue;
    assertable.assertThat(actual, ReturnsTrue());

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

  • 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. Alternatively,

    • 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. For more information, see matlab.unittest.qualifications.Verifiable.

    • 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.

    • 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.

Introduced in R2013a