Three methods that could be used to launch a test run for expression rule test cases when required are:

A process model invoked via an API. A process model can be designed to run test cases for expression rules using the a!testRule() function or the Test Rule smart service. This process model can be exposed as a web API with an HTTP method such as POST or PUT, allowing external systems or applications to invoke it through an HTTP request.

A process model exposed to users as an action. A process model can also be designed to run test cases for expression rules using the same function or smart service as above. This process model can be exposed to users as an action on an interface, such as a button or a link, allowing users to trigger it manually when needed.

A SAIL interface embedded in a report. A SAIL interface can be created to run test cases for expression rules using the a!testRule() function. This interface can be embedded in a report, such as a grid or a chart, allowing users to view the test results interactively on an interface. References: Automated Testing for Expression Rules, a!testRule() Function, Test Rule Smart Service, Web APIs, SAIL Interfaces