Add get_current_vm_step

[franciszekjob]

Closes #3824

Introduced changes

Introduce get_current_vm_step as part of snforge_std::testing

Checklist

• Linked relevant issue
• Updated relevant documentation
• Added relevant tests
• Performed self-review of the code
• Added changes to CHANGELOG.md

[ddoktorski]

In the current implementation this doesn't actually work for contracts since each contract call is executed in a separate VM. Was it intended to support contract testing at all?

[cptartur]

Please re-request after changes from slack discussion are addressed

[franciszekjob]

In the current implementation this doesn't actually work for contracts since each contract call is executed in a separate VM. Was it intended to support contract testing at all?

Good catch! I've changed the code so now it also adds steps from calls's resource, should be fine. Please take a look.

[cptartur]

Can we add some kind of sanity check where we assert specific value of used steps (or a delta of steps)? So we detect eventually regressions if these change significantly.

[cptartur]

I see that we have a test below that does this for contracts but let's have one for top level calls as well.

[franciszekjob]

I've extended test_get_current_vm_step so now it checks steps after two possible scenarios: syscalls only in top call + syscalls both in top call and inner calls. It should cover this and the comment below, pls TAL.

[cptartur]

Also, let's add a test where we have inner calls and these inner calls do some expensive computation (not just increment some counter, but call some more expensive syscalls). Check if steps value is "large enough" there.

[cptartur]

We should be able to roughly estimate the steps value from fee mechanism docs https://docs.starknet.io/learn/protocol/fees#vm-resources similarly as we do in our gas integration tests and check if values in the test are roughly withing the expected range.

[franciszekjob]

Responded in comment above.

[cptartur]

I'd reword this so it's more of a reference than a tutorial, explanations like that fit more in the snforge Overview section and we can assume users looking at the reference are familiar with these docs.

Take a look at fuzzable docs for example, let's show an reference for what get_current_vm_step shows and does and keep a simple example without too much explanations.

[franciszekjob]

I'd reword this so it's more of a reference than a tutorial, explanations like that fit more in the snforge Overview section and we can assume users looking at the reference are familiar with these docs.

Take a look at fuzzable docs for example, let's show an reference for what get_current_vm_step shows and does and keep a simple example without too much explanations.

It's not shown in snforge Overview, hence the example here has more detailed explanation.

I've reduced the textual description, but kept contract and test code (13f1af4).

We could put a small tutorial to snforge overview section if you really want, lmk