Test-cases play an important roll for high quality of software testing. Inadequate test-cases may cause bugs remaining after testing. Overlapped ones lead to the increases in testing costs. This paper proposes the Event InterActions Graph (EIAG) representing behavior of concurrent programs including any task-type and the cooperated paths (copaths) on the EIAG as test-cases, and describes the test-case generation tool (TCgen) for concurrent programs written in Ada programming language. The EIAG consists of Event Graphs and Interactions. An Event Graph is a control flow graph of a program unit in a concurrent program. The Interactions represent interactions such as synchronizations between the program units. $TCgen$ generates test-cases as copaths from an Ada concurrent program. The generated copaths satisfy given testing criteria. They can find some communication errors in testing and detect unreachable statements which concern interactions. It is, however, necessary to validate feasibility of the generated copaths.