A test suite class contains a list of test classes, test suite classes, test procedures, and test suite procedures. It helps you to group and organize test classes. When a test suite class is run, all the test classes, test procedures, test suite classes, and test suite procedures added in the test suite class willl be run.

The ABL class is identified as a test suite by the @TestSuite annotation and you can add the test classes to this test suite as comma separated values to the classes attribute and test procedures as comma separated values to the procedures attribute as shown in the examples below: 
@TestSuite(classes= "Org.test.TestClass1, Org.test.TestClass2").

@TestSuite(procedures= "Org/test/test_proc1.p, Org/test/test_proc2.p").

@TestSuite(classes= "Org.test.TestClass2, Org.test.TestClass4", 
procedures= "Org/test/test_proc1.p, Org/test/test_proc2.p").

If @TestSuite annotation is present, only the classes and procedures attribute values are read for identifying the test cases and the business logic is not executed.

Here is an example of test suite:
USING Progress.Lang.*.
ROUTINE-LEVEL ON ERROR UNDO, THROW.
@TestSuite(procedures="test.p").
@TestSuite(procedures="testLogin.p").
@TestSuite(classes="testcls.cls").
CLASS testSuite: 

END CLASS..