Test Case is a collection of unique test steps. Test steps include keywords, control flow constructs, function library files, and service repository files. Keywords can either accept either no input or retrieve objects and data. Each test step will return an output that can be used as an input for additional steps.

A test case can be executed individually by using “Run Now” and “Debug Now” buttons within OpKey. Users can execute multiple test cases together by adding them to a suite and then running an execution of that specific suite.

Quick Start Screencast : 

Test Case module also has an integrated recording feature which helps in creating a test case easily & quickly by recording actions performed over a web (or mobile) application.

For detailed information on Test Case, please refer: Working with Test Cases