verifyReturnsTrue

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

Verify function returns true

Syntax

verifyReturnsTrue(testCase,actual)

verifyReturnsTrue(testCase,actual,diagnostic)

Description

verifyReturnsTrue(testCase,actual) verifies that actual is a function handle that returns the logical scalar 1 (true).

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

Input Arguments

testCase — Test case

matlab.unittest.qualifications.Verifiable object

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.

actual — Value to test

any value

Value to test, specified as a value of any data type. Although you can provide a value of any data type, the test fails if actual is not a function handle.

Example: @() myFunction(1,2)

Example: @() ~strcmp('a','b')

diagnostic — Diagnostic information to display

string array | character array | function handle | array of matlab.automation.diagnostics.Diagnostic objects

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

Attributes

Sealed

true

To learn about attributes of methods, see Method Attributes.

Examples

Test if Function Returns True

Test if the actual value is a function handle that returns true.

Create a test case for interactive testing.

testCase = matlab.unittest.TestCase.forInteractiveUse;

Test the true function.

verifyReturnsTrue(testCase,@true)

Verification passed.

Test the false function. The test fails because false does not return true.

verifyReturnsTrue(testCase,@false)

Verification failed.
    ---------------------
    Framework Diagnostic:
    ---------------------
    verifyReturnsTrue failed.
    --> The function handle did not evaluate to "true".
    --> Returned value:
              logical
            
               0
    
    Evaluated Function:
      function_handle with value:
    
        @false
    ------------------
    Stack Information:
    ------------------
    In C:\work\TestIfFunctionReturnsTrueExample.m (TestIfFunctionReturnsTrueExample) at 19

Test if a call to isequal returns true given two equivalent numeric values.

verifyReturnsTrue(testCase,@() isequal(1,single(1)))

Verification passed.

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

verifyReturnsTrue(testCase,@() ~strcmp('a','b'))

Verification passed.

Test a function that returns a vector of true values. The test fails because the returned value is nonscalar.

verifyReturnsTrue(testCase,@() strcmp('a',{'a','a'}))

Verification failed.
    ---------------------
    Framework Diagnostic:
    ---------------------
    verifyReturnsTrue failed.
    --> The function handle did not return a scalar. The return value had a size of [1  2].
    --> Returned value:
              1×2 logical array
            
               1   1
    
    Evaluated Function:
      function_handle with value:
    
        @()strcmp('a',{'a','a'})
    ------------------
    Stack Information:
    ------------------
    In C:\work\TestIfFunctionReturnsTrueExample.m (TestIfFunctionReturnsTrueExample) at 33

Test a function that returns a numeric value. The test fails.

verifyReturnsTrue(testCase,@ones, ...
    "Returned value must be a logical scalar.")

Verification failed.
    ----------------
    Test Diagnostic:
    ----------------
    Returned value must be a logical scalar.
    ---------------------
    Framework Diagnostic:
    ---------------------
    verifyReturnsTrue failed.
    --> The function handle did not return a logical value. The return value was of type "double".
    --> Returned value:
                 1
    
    Evaluated Function:
      function_handle with value:
    
        @ones
    ------------------
    Stack Information:
    ------------------
    In C:\work\TestIfFunctionReturnsTrueExample.m (TestIfFunctionReturnsTrueExample) at 37

Tips

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

  import matlab.unittest.constraints.ReturnsTrue
  testCase.verifyThat(actual,ReturnsTrue)
  

• An alternative to verifyReturnsTrue is the verifyTrue method. verifyTrue runs faster and is easier to use, but verifyReturnsTrue provides slightly better diagnostic information. In this example, both tests fail, but the second test displays the function handle as part of the diagnostics.

  actual = 1;
  expected = 2;
  testCase = matlab.unittest.TestCase.forInteractiveUse;
  verifyTrue(testCase,isequal(actual,expected))
  verifyReturnsTrue(testCase,@()isequal(actual,expected))

• 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