One risk we must handle during run sessions is exceptions, as they can have a fatal impact on the robustness of our automated tests. UFT provides the recovery scenario as a built-in solution (refer to Chapter 6, Event and Exception Handling), but it is quite complex to implement and may hinder the performance of the test.
In this recipe, we will see how to implement a simple recovery mechanism that is integrated with the controller (described previously) and that utilizes the same design pattern used for the regular actions to implement recovery procedures.
Add an Environment variable to the test. Name it ERR_DEFAULT and set its value to StopRunSession. Add another Environment variable named ERR_9 and set its value to ClearError. Create a function library named cls.EventHandler.vbs in the Lib folder, as already described in the previous recipe.
The following code shows a sample procedure implemented as an Action. The StopRunSession class is used in our framework to handle an exception by stopping the run session, and it is used as default. Write the following code in the cls.EventHandler.vbs function library:
Class StopRunSession
' --------------------------------------------------
' Reusable Action: StopRunSession
' Description: Stops the run in case of an unhandled error/exception
' --------------------------------------------------
Public Status
Public Iteration
Public StepNum
Public dt
Public Details
Public Function Run()
me.Details = "Ended with "
me.Status.[=]Reporter.RunStatus
'--- Report
Call ReportActionStatus(me)
'--- Stops the run session
ExitTest(Reporter.RunStatus)
End Function
Private Sub Class_Initialize
Call InfoClassInstance(me, C_OBJ_LOADED_MSG)
Set me.Status = [As Num](0)
End Sub
Private Sub Class_Terminate
Call InfoClassInstance(me, C_OBJ_UNLOADED_MSG)
Set me.Status = Nothing
End Sub
End ClassThe procedure was built based on the same command wrapper pattern as the regular reusable Actions. The procedure will be invoked any time by the RunMappedProcedure method (shown in the following code snippet) of the EventHandler class, which will not find a matching procedure for a given error code.
Note that in this sample implementation, the value of the procedure associated with the error number is taken from the environment, but more elaborate design patterns could have been mapped into an XML file or DB:
Class EventHandler
Function RunMappedProcedure(ByVal strError)
Dim oProcedure
'--- Try to execute the procedure associated with the error (if exists)
If GetClassInstance(oProcedure, Environment("ERR_" & CStr(Abs(strError)))) = 0 Then
RunMappedProcedure = oProcedure.Run
Exit Function
End If
'--- Try to execute the default procedure to handle errors (if exists)
If GetClassInstance(oProcedure, Environment("DEFAULT_ERROR_HANDLER")) Then
RunMappedProcedure = oProcedure.Run
Exit Function
End If
End Function
End ClassThe following code shows another sample procedure implemented as an Action. It is used in our test automation framework to handle a specific exception by clearing the error, and the procedure is mapped to error code number 9 (Subscript out of range). This can be written in the cls.EventHandler.vbs function library file, as follows:
Class ClearError
' --------------------------------------------------
' Reusable Action: ClearError
' Description: Clears the error in case of an unhandled error/exception
' --------------------------------------------------
Public Status
Public Iteration
Public StepNum
Public dt
Public Details
Public Function Run()
me.Details = "Ended with "
me.Status.[=]0
'--- Report
Call ReportActionStatus(me)
'--- Clears the error
Err.Clear
End Function
Private Sub Class_Initialize
Call InfoClassInstance(me, C_OBJ_LOADED_MSG)
Set me.Status = [As Num](0)
End Sub
Private Sub Class_Terminate
Call InfoClassInstance(me, C_OBJ_UNLOADED_MSG)
Set me.Status = Nothing
End Sub
End ClassWhen the controller tries to execute the Action, it sets a kind of try-catch mechanism with On Error Resume Next, as shown here:
' ------------------------------------- '--- Execute the Action ' ------------------------------------- On Error Resume Next '--- Try oAction.Run ' ------------------------------------- If Err.Number <> 0 Then 'Catch me.ErrorHandler.RunMappedProcedure(Err.Number) End If On Error Goto 0
So if an error occurs, it will be passed to ErrorHandler via the RunMappedProcedure method, and it will use either the specifically defined procedure for the error or the default procedure. This ensures that no exceptions will be left unhandled.