{"id":12015,"date":"2025-06-05T11:37:53","date_gmt":"2025-06-05T09:37:53","guid":{"rendered":"https:\/\/www.basyskom.de\/?p=12015"},"modified":"2025-06-06T10:15:24","modified_gmt":"2025-06-06T08:15:24","slug":"how-to-do-black-box-testing-of-an-opc-ua-server-with-cucumber-js","status":"publish","type":"post","link":"https:\/\/www.basyskom.de\/en\/how-to-do-black-box-testing-of-an-opc-ua-server-with-cucumber-js\/","title":{"rendered":"How to do black box testing of an OPC UA server with Cucumber-JS"},"content":{"rendered":"\t\t
\n\t\t\t\t
\n\t\t\t\t\t
\n\t\t\t\t
\n\t\t\t\t
\n\t\t\t\t\t

Motivation<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
\n\t\t\t\t
\n\t\t\t\t\t\t\t\t\t

The steadily growing importance of OPC UA has increased the demand for server applications to integrate existing or new devices into an OPC UA based ecosystem.\u00a0 An OPC UA server application usually includes business logic to handle method calls or to react to external inputs. If the server implements an existing\u00a0companion specification<\/a>, the behavior of the server also has to conform strictly to the specification in order to ensure interoperability with applications from other manufacturers.<\/p>\n

\u00a0<\/p>\n

While a good unit test coverage of the server’s code is a helpful building block to achieve and maintain compatibility with the specification, running tests against the public interface the server exposes to its clients is equally important to ensure that modifications to the code don’t introduce unwanted behavioral changes. This article demonstrates the basics of implementing black box tests for an OPC UA server that implements the\u00a0AutoId<\/a>\u00a0companion specification and exposes an\u00a0RfidReaderDeviceType<\/a> object.<\/p>\n

\u00a0<\/p>\n

We provide the full source code for the example project on Github<\/a>.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

\n\t\t\t\t
\n\t\t\t\t\t

What Is Black Box Testing?<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
\n\t\t\t\t
\n\t\t\t\t\t\t\t\t\t

Black box testing is a way of software testing where the application under test is regarded as an opaque box with interfaces to the outside world which are tested against a specification of expected behavior. This means that the tests must not require knowledge of the application’s inner workings and ideally would still pass if the entire application would be rewritten from scratch.<\/p>

\u00a0<\/p>

Depending on the architecture of the application, it might still be necessary to create some test fixture. For example, the application might depend on inputs from attached devices or external processes it communicates with. In such a case, a controllable mockup of the external system is required in order to trigger state changes or events in the application.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

\n\t\t\t\t
\n\t\t\t\t\t

Cucumber and Gherkin<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
\n\t\t\t\t
\n\t\t\t\t\t\t\t\t\t

Cucumber<\/a>\u00a0is a\u00a0BDD<\/a>\u00a0tool that describes itself as a “tool for running automated acceptance tests, written in plain language”. It uses test definitions written in the\u00a0Gherkin<\/a>\u00a0language which consists of plain language held together by some keywords and a certain structure.<\/p>

\u00a0<\/p>

A feature is a collection of scenarios which each have a\u00a0 short description and consist of one or more steps starting with a keyword. Step definitions can contain placeholders to enable running the same check with different values to serve as inputs to the test setup or as expected output values.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

\n\t\t\t\t
\n\t\t\t\t\t
Feature: State handling for running scans and reader online\/offline status must be checked\n  If the reader goes offline, the server state must change to Error and starting a scan must be forbidden.\n  While a scan is running, no new scan can be started.\n \n  Scenario: Attempt start while scan is running\n    Given a connected OPC UA client\n    And a running scan\n    Then I should see that the DeviceStatus is "Scanning"\n    When I call the ScanStart method with DataAvailable "false"\n    Then I should see that the method returned "BadInvalidState"\n    And I should see that the DeviceStatus is "Scanning" <\/code><\/pre>