Document appveyor.yml that downloads the dependencies

[jayvdb]

Personally I dislike having 'install.ps1' and 'run_with_env.cmd' in my repository. I would prefer a solution where they are hosted elsewhere, like OSX python builds on Travis use http://github.com/MacPython/terryfy . I suspect others feel the same, and I believe it will help projects add Win32 test builds/releases if the documentation at the https://packaging.python.org/en/latest/appveyor.html only requires adding a single file (appveyor.yml) to the repository.

Originally my appveyor.yml downloaded the necessary files from https://raw.githubusercontent.com/pypa/python-packaging-user-guide/master/source/code/ .

(https://github.com/wikimedia/pywikibot-core/blob/f22ecb02620ad4cc374c832d8978f147ed54e518/.appveyor.yml)

I've now updated it to use python-appveyor-demo because I prefer the (newer?) run_with_env.cmd approach, and in the process improved how it downloads and uses the extra files. You can see the proposed version here: https://gerrit.wikimedia.org/r/#/c/208957 (gosh I hate learning PowerShell, but its for a good cause...:)

Would documenting this fit within your demo project. Where would it go? A second appveyor.yml that can be used as a sample?

Also proposed the same at pypa/packaging.python.org#155

[ogrisel]

Maybe a second (untested) appveyor.yml file to document this approach is a good idea. Maybe name it appveyor-nodeps.yml for instance and reference / explain it in a new section in the README.md file.

Note: if I read the diff of https://gerrit.wikimedia.org/r/#/c/208957, it seems that the CMD_IN_ENV variable is not defined.

[ogrisel]

Maybe we should fine a way to use the appveyor cache to avoid downloading those scripts over and over again. But that would make the powershell snippet more complex and harder to understand and maintain.

[jayvdb]

CMD_IN_ENV variable fixed. Much appreciated.

Will work on a appveyor-nodeps.yml soon.

[jayvdb]

Ugh; using CMD_IN_ENV caused it to fail.
https://ci.appveyor.com/project/jayvdb/pywikibot-core/build/1.0.appveyor-build-extras.287/job/t9n2w40whfpebuo1

[jayvdb]

A fairly simple version at

jayvdb@4b785b8

With the Appveyor settings changed to use appveyor-nodeps.yml, here is the passing build

https://ci.appveyor.com/project/jayvdb/python-appveyor-demo/build/1.0.12

I'll add some documentation, fix any issues you see, and submit a PR tomorrow.