Custom Thread Groups - Add support for IteratingController implement

[3dgiordano]

Hi @undera

It was detected that the plugin is not using the IteratingController interface and is therefore not calling the updateIterationIndex method (in VirtualUserController).

The call to this method is responsible for creating the variable in the execution context with the value of the current iteration number of the running Thread Group.
Scripts that use this variable when migrating from Thread Group to some Thread Group in this plugin fail because the current implementation does not create that variable.

It is proposed to incorporate the use of the IteratingController interface in VirtualUserController to call updateIterationIndex to create that variable, just as the native Thread Group currently does with LoopController.

For the methods to be implemented with support for this interface, ideas were taken from JMeter's LoopController implementation (in an attempt to be aligned).

On JMeter 5.2-rc4 was added IteratingController and the updateIterationIndex method (apache/jmeter@b230954)
The change is aligned with the minimum requirement which is version 5.2.1
And the proposal implementation was also tested in JMeter 5.2.1+.

I look forward to your review, as well as any suggestions or changes you think are appropriate.

Regards
David

[undera]

@3dgiordano One question: does IteratingController exist in JMeter 5.2.1? Just making sure we get no compatibility issues with old installations

[3dgiordano]

Hi @undera

Apologies for not providing this information in the original PR documentation.
JMeter 5.2-rc4 added IteratingController and the updateIterationIndex method in the following commit

apache/jmeter@b230954

I also forgot to mention that it was tested in JMeter 5.2.1 and later.

[undera]

Thank you for clarifications!