Allow ${{}} exprs to call methods from external python modules

[zebralt]

#301

This PR adds the evaluator RemoteMethodCallEvaluator, It extends CodeEvaluator by allowing a RMC expression <module>:≤python function call> to be inserted in ${{}} expressions, which so far only accepts pure Python code.

RMC expression

A RMC expr allows you to invoke a method/function from a given python module:

${{ std:response.ok }}

The right member of the expression must either be a a raw name as above or a typical Python call:

std:response.status_is(200)
std:response.status_is(code=300, detail='jon')

std

In addition to any module name, the left member also accepts two values: the empty string and std. Those two values means the module to import from is scanapi/std.py. std.py is meant to be a standard library of methods shipped with scanapi.

For now, std is only a module, but maybe it should become a package instead to avoid putting everything into a single file.

How modules are imported

Modules are imported at evaluation time. Path resolution works the same as a regular import , i.e to import a local module you'll need to have it in your current working directory.

How functions are called

The function is imported from its module, then

• if args/kwargs were provided in the right member of the RMC expr, they are bound to the function using functools.partial;
• the RMC evaluator attempts to feed vars to the function as efficiently as possible here, in the following order:
  • if the function's spec can be inspected, the evaluator tries to see which names the function expects and feeds it only these, e.g.

vars = {'response': ResponseObject(), 'ids': [...]}
def response_ok(response):
    return response.status == 200
call_against_vars(f, (), {}, vars)  # will only send vars['response'] to response_ok

• if there is no key in the spec that can be correlated with vars's keys, an exception is raised.
• if the spec cannot be inspected (such is the case of builtins), vars is fed as a single positional argument to the function.
• if the spec has a vars argument, vars is fed as a keyword argument under that name.

---

#301 suggested that vars be fed implicitly to the function, but there may be a case for doing it explicitly instead; the right member is parsed using the ast module, and we could use it to parse name arguments as well; that wouldn't be too much of a stretch:

${{ std:response_ok(response) }}  # search for 'response' name in vars

[github-actions]

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[zebralt]

Weird, my local black setup gives a completely different result ...

would reformat scanapi\scanapi\__main__.py
would reformat scanapi\scanapi\hide_utils.py
would reformat scanapi\scanapi\reporter.py
would reformat scanapi\scanapi\scan.py
would reformat scanapi\scanapi\settings.py
would reformat scanapi\scanapi\utils.py
would reformat scanapi\scanapi\tree\request_node.py

[hebertjulio]

Hey @camilamaia

This month i will take a vacation, and after i can work at this PR if necessary.

[camilamaia]

@hebertjulio perfect! It would help a lot. Have a great vacation!

[camilamaia]

@zebralt Sorry for the HUGE delay with this PR. This is a complex issue that you made a great effort to tackle.

We are trying to bring it back now. I am solving the conflicts and the format issues. @jlugao will help us testing it. @zebralt let me know if you also want to keep working on it.

[camilamaia]

@jlugao I solved all conflicts 👌 It is still failing in some static analysis (https://github.com/scanapi/scanapi/pull/324/checks?check_run_id=3433068011 and https://github.com/scanapi/scanapi/pull/324/checks?check_run_id=3433067531) but we can tackle them later, before merging the PR.

I believe it is all good now for you to test it. As a guide, I would suggest you:

• First, follow our Run ScanAPI Locally doc
• And then, this PR description instructions

Let me know how it goes! I can help with any blocker :) Also, feel free to join our discord server https://discord.scanapi.dev if you want some help via chat

[camilamaia]

Sorry, closing this PR for now since there was no recent activity 🧹 If you want to update it, feel free to reopen it.