Do not require name or prefix if we are running create with dry-run

[jaimergp]

Description

Folks often rely on create --dry-run to run solver diagnostics. For this operation, prefixes or env names are not needed, yet they are still required in the CLI. It's common to see invocations such as:

$ conda create -n unused --dry-run ...

Or the shorthand (with x being the env name):

$ conda create -dnx ...

However it should be perfectly fine to run:

$ conda create --dry-run ...

This is what we see in this PR.

Checklist - did you ...

• Add a file to the news directory (using the template) for the next release's release notes?
• Add / update necessary tests?
• Add / update outdated documentation?

[codspeed-hq]

CodSpeed Performance Report

Merging #13941 will not alter performance

_{Comparing jaimergp:dry-run-create-does-not-need-prefix-name (0fc7f6e) with main (eb45954)}

Summary

✅ 21 untouched benchmarks

[travishathaway]

Just a couple requests for changes. Please let me know if any seem unreasonable. Will be happy to review once more.

[travishathaway]

Suggested change

	context._argparse_args.prefix = os.path.join(mktemp(), "dry-run-create-env")
	args.prefix = os.path.join(mktemp(), "dry-run-create-env")
	context.__init__(argparse_args=args)

I think this is slightly better. No need to access a protected property when we can simply re-initialize the object. Performance penalty should be negligible.

Also, Could we make "dry-run-create-env" a constant and define it in conda.base.constants. Not necessary, but would help keep the code a little more organized and provide a central place to look up this value in case it is ever needed.

[jaimergp]

Are we sure we are not overriding some stuff from os.environ with that call? 🤔 I always get nervous when I reinitialize the context outside of the tests 😬

+1 to the 2nd suggestion.

[jaimergp]

Applied your suggestions. The new tests seem to be passing locally.

[travishathaway]

No reason to worry about overriding stuff from os.environ. I double checked the code. We just need to make sure we initialize it like we do in conda.cli.main.main_subshell by pass the argparse args:

• conda/conda/cli/main.py

  Line 72 in a261ade

  context.__init__(argparse_args=pre_args)

[travishathaway]

🚀

[travishathaway]

Looking good. Thanks for being receptive to my suggestions 😄.

[beeankha]

Thanks for doing this work, @jaimergp !