matlab.unittest.constraints.Constraint Class

Namespace: matlab.unittest.constraints

Fundamental interface for constraints

Description

The matlab.unittest.constraints.Constraint class provides an interface that you can use to encode comparison logic in qualifications and produce diagnostic information. All constraints are derived from the Constraint class, whether they are user-supplied constraints or framework constraints.

To create a custom constraint class, derive your class from matlab.unittest.constraints.Constraint and implement its abstract methods:

• Implement the satisfiedBy method to encode the comparison logic.

• Implement the getDiagnosticFor method to produce diagnostic information when the testing framework evaluates the actual value against the constraint.

Then, you can use your Constraint subclass with the assertThat, assumeThat, fatalAssertThat, and verifyThat qualification methods from the matlab.unittest.qualifications namespace.

To create a constraint that can be combined and negated using the and (&), or (|), and not (~) operators, derive your class from matlab.unittest.constraints.BooleanConstraint instead.

Class Attributes

Abstract	true
HandleCompatible	true

For information on class attributes, see Class Attributes.

Methods

Public Methods

satisfiedBy

tf = satisfiedBy(constraint,actual) Determine if the value satisfies the constraint. This method provides the comparison logic. Input Arguments constraint — Constraint, specified as a matlab.unittest.constraints.Constraint object. actual — Value to test. Output Arguments tf — Whether the value satisfies the constraint, returned as a 1 or 0 of data type logical. Abstract: true

getDiagnosticFor

diagnostic = getDiagnosticFor(constraint,actual) Produce diagnostic information for the value being evaluated against the constraint. Typically, the testing framework calls this method when it encounters a qualification failure. Therefore, a more detailed analysis after a failure can be more efficiently handled by getDiagnosticFor than the satisfiedBy method. Input Arguments constraint — Constraint, specified as a matlab.unittest.constraints.Constraint object. actual — Value to test. Output Arguments diagnostic — Diagnostic information to display, returned as a matlab.automation.diagnostics.Diagnostic object. 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. Abstract: true

Examples

Create Constraint to Test for Size

Create a constraint that determines if a value is the same size as an expected value.

In a file in your current folder, create a class named IsSameSizeAs that derives from matlab.unittest.constraints.Constraint, and implement the satisfiedBy and getDiagnosticFor methods.

classdef IsSameSizeAs < matlab.unittest.constraints.Constraint
    properties (SetAccess=immutable)
        ValueWithExpectedSize
    end

    methods
        % Class constructor
        function constraint = IsSameSizeAs(value)
            constraint.ValueWithExpectedSize = value;
        end

        % Determine if the actual value satisfies the constraint 
        function tf = satisfiedBy(constraint,actual)
            tf = constraint.sizeMatchesExpected(actual);
        end

        % Produce a diagnostic for the constraint
        function diagnostic = getDiagnosticFor(constraint,actual)
            import matlab.automation.diagnostics.StringDiagnostic
            if constraint.sizeMatchesExpected(actual)
                diagnostic = StringDiagnostic("IsSameSizeAs passed.");
            else
                diagnostic = StringDiagnostic( ...
                    "IsSameSizeAs failed." + newline + "Actual Size: [" ...
                    + int2str(size(actual)) + "]" + newline ...
                    + "Expected Size: [" ...
                    + int2str(size(constraint.ValueWithExpectedSize)) ...
                    + "]");
            end
        end
    end

    methods (Access=private)
        % Determine if the actual and expected values are the same size
        function tf = sizeMatchesExpected(constraint,actual)
            tf = isequal(size(actual), ...
                size(constraint.ValueWithExpectedSize));
        end
    end
end

Create a test case for interactive testing.

testCase = matlab.unittest.TestCase.forInteractiveUse;

Verify that a 5-by-5 matrix of zeros is the same size as a 5-by-5 matrix of ones by using the IsSameSizeAs constraint.

testCase.verifyThat(zeros(5),IsSameSizeAs(ones(5)))

Verification passed.

Version History

Introduced in R2013a