Stateful Fuzz(Open), what is the need of creating new instance on every run?

[sh0lt0]

Stateful fuzz runs based on the previous state, why is a new instance created on every run
testCon Contract; function setUp(){ testCon = new Contract();}
I tried commenting the creation of new instance but the test showed no test to fuzz.

[EngrPips]

Hello @sh0lt0 , so i had to go re-run a stateful fuzzing test that i had initially written and read the stack trace of all the transaction that was executed during the stateful fuzz and i found out that the contract was only set up once for me and the remaining calls was between the handler and the invariant test i wrote. i am not sure why your own stateful fuzz is setting up new contract on every run. thats unusual maybe you are not doing something right.

[sh0lt0]

Hey, I meant stateful fuzz without handler, I am sharing the snippet of my test

I have deliberately commented out the line where new instance is created inside setUp() but the on running the test it gives failed test - no contract to fuzz on the other hand, when I remove the comment, it runs fine.
So, here my question arises what is the need of this line statefullFuzzCont = new StatefulFuzzCatches();

Apart from my initial question, I am curious how can I read my stack trace where you found out the calls and instance creation?

[EngrPips]

You didn't import StdInvariant, why is that ? . below is what my invariant test suite look like

You need to import StdInvariant to do stateful fuzzing.

[EngrPips]

The security and auditing course have a section where Patrick teaches how to write a proper invariant test suite. If you will follow this link https://updraft.cyfrin.io/courses/security/tswap/stateful-and-stateless-fuzzing?lesson_format=video it will take you the course on cyfrin updraft where Patrick teaches about stateless fuzzing, open stateful fuzzing and controlled stateful fuzzing

[sh0lt0]

Hey, thanks for your help, I think I need to rewatch the modules to get more clarity.
Could you please let me know how did you look at the stack trace please?

[EngrPips]

to look at the stack trace you can just put the -vvvv flag at the of your command to run your test

[sh0lt0]

I always run the command with max verbosity but I never looked it from a different perspective, thanks for the enlightening.

[EngrPips]

Anytime friend