Main Content

verifyNumElements

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

Verify value has specified element count

Description

example

verifyNumElements(testCase,actual,expectedNumElements) verifies that actual is a MATLAB® array with the expected number of elements.

example

verifyNumElements(testCase,actual,expectedNumElements,diagnostic) also associates the diagnostic information in diagnostic with the qualification.

Input Arguments

expand all

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

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

Expected number of elements in the array, 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.unittest.diagnostics.Diagnostic objects.

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.

Example: "My Custom Diagnostic"

Example: @dir

Attributes

Sealedtrue

To learn about attributes of methods, see Method Attributes.

Examples

expand all

Test if the actual value has the specified number of elements.

Create a test case for interactive testing.

testCase = matlab.unittest.TestCase.forInteractiveUse;

Verify that a scalar has an element count of one.

verifyNumElements(testCase,3,1)
Verification passed.

Test the element count of a matrix [1 2 3; 4 5 6]. The test fails because the matrix has six elements.

verifyNumElements(testCase,[1 2 3; 4 5 6],5)
Verification failed.
    ---------------------
    Framework Diagnostic:
    ---------------------
    verifyNumElements failed.
    --> The value did not have the correct number of elements.
        
        Actual Number of Elements:
             6
        Expected Number of Elements:
             5
    
    Actual Value:
         1     2     3
         4     5     6
    ------------------
    Stack Information:
    ------------------
    In C:\work\TestForNumberOfElementsExample.m (TestForNumberOfElementsExample) at 18

Verify that an identity matrix has the expected number of elements.

n = 7;
verifyNumElements(testCase,eye(n),n^2)
Verification passed.

Test the element count of a cell array of character vectors.

actual = {'Mercury','Gemini','Apollo'};
verifyNumElements(testCase,actual,3)
Verification passed.

Test the element count of a scalar structure with two fields. The test fails because the structure has only one element.

s.field1 = 1;
s.field2 = zeros(1,10);
verifyNumElements(testCase,s,2,"Value must have two elements.")
Verification failed.
    ----------------
    Test Diagnostic:
    ----------------
    Value must have two elements.
    ---------------------
    Framework Diagnostic:
    ---------------------
    verifyNumElements failed.
    --> The value did not have the correct number of elements.
        
        Actual Number of Elements:
             1
        Expected Number of Elements:
             2
    
    Actual Value:
      struct with fields:
    
        field1: 1
        field2: [0 0 0 0 0 0 0 0 0 0]
    ------------------
    Stack Information:
    ------------------
    In C:\work\TestForNumberOfElementsExample.m (TestForNumberOfElementsExample) at 35

Tips

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

    import matlab.unittest.constraints.HasElementCount
    testCase.verifyThat(actual,HasElementCount(expectedNumElements))
  • 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.

Introduced in R2013a