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Class: matlab.unittest.qualifications.Verifiable
Namespace: matlab.unittest.qualifications

Verify value has specified length



verifyLength(testCase,actual,expectedLength) verifies that actual is a MATLAB® array with the expected length. The length of an array is defined as the length of the largest dimension of that array.


verifyLength(testCase,actual,expectedLength,diagnostic) also associates the diagnostic information in diagnostic with the qualification.

Input Arguments

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Test case, specified as a matlab.unittest.qualifications.Verifiable object. Because the matlab.unittest.TestCase class subclasses matlab.unittest.qualifications.Verifiable and inherits its methods, testCase is typically a matlab.unittest.TestCase object.

Value to test, specified as an array of any data type.

Expected array length, specified as a nonnegative integer scalar.

Diagnostic information to display when the qualification passes or fails, specified as a string array, character array, function handle, or array of matlab.automation.diagnostics.Diagnostic objects.

Depending on the test runner configuration, the testing framework can 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.

Example: "My Custom Diagnostic"

Example: @dir



To learn about attributes of methods, see Method Attributes.


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Test if the actual value has the specified length.

Create a test case for interactive testing.

testCase = matlab.unittest.TestCase.forInteractiveUse;

Verify that the row vector [1 3 5] has a length of three.

verifyLength(testCase,[1 3 5],3)
Verification passed.

Verify that the length of an array is the length of its largest dimension.

Verification passed.

Test if the length of a 2-by-2 identity matrix is four. The test fails.

verifyLength(testCase,eye(2),4,"Value must have a length of four.")
Verification failed.
    Test Diagnostic:
    Value must have a length of four.
    Framework Diagnostic:
    verifyLength failed.
    --> The array has an incorrect length.
        Actual Length:
        Expected Length:
    Actual Value:
         1     0
         0     1
    Stack Information:
    In C:\work\TestForArrayLengthsExample.m (TestForArrayLengthsExample) at 22

Test the length of a cell array of character vectors.

actual = {'Mercury','Gemini','Apollo'; ...
    'Skylab','Skylab B','ISS'};
Verification passed.


  • verifyLength is a convenience method. For example, verifyLength(testCase,actual,expectedLength) is functionally equivalent to the following code.

    import matlab.unittest.constraints.HasLength
  • 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:

    • 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 tests. A failure at the assertion point renders the current test 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 is so fundamental that continuing testing does not make sense. Fatal assertion qualifications are also useful when fixture teardown does not restore the environment state correctly, and aborting testing and starting a fresh session is preferable. For more information, see matlab.unittest.qualifications.FatalAssertable.

Version History

Introduced in R2013a