Support for conda as a language

[xhochy]

Fixes #1204

Example usage

.pre-commit-hooks.yaml:

- id: black-conda
  name: black-conda
  description: "Black: The uncompromising Python code formatter"
  entry: black
  language: conda
  require_serial: true
  types: [python]

environment.yml:

channels:
  - conda-forge
  - defaults
dependencies:
  - black=19.10b0

[xhochy]

This is lacking sufficient tests, I'm unsure what should be tested and am open for suggestions.

[xhochy]

This has now all review comments incorporated and tests are passing except for Windows. There we need to download a lightweight conda (take an exe from https://repo.anaconda.com/pkgs/misc/conda-execs/) to get the tests passing. This needs an modification of the Azure template like https://github.com/asottile/azure-pipeline-templates/blob/f8721c757e218487ca0bb38af0201b2a04e9ed52/job--python-tox.yml#L63-L68 @asottile Should I modify the template to always install a conda.exe on Windows or make this conditional on some parameter?

[asottile]

there's a pre_test list where you can install whatever you need 👍

for example, here's what it does to install ruby / swift on linux:

pre-commit/azure-pipelines.yml

Lines 41 to 46 in 023b337

	pre_test:
	- task: UseRubyVersion@0
	- bash: |
	testing/get-swift.sh
	echo '##vso[task.prependpath]/tmp/swift/usr/bin'
	displayName: install swift

[asottile]

seems good!

[xhochy]

@asottile Adjusted all things and CI is still green. :)

[asottile]

this should be part of install_environment I believe

[xhochy]

Should these be removed here then?

[asottile]

yes -- you can take precedent from the other languages that use this function

[xhochy]

@asottile Azure is failing with missing files in the template repo but these actually exist. Do you have an idea what is going wrong here?

[asottile]

@asottile Azure is failing with missing files in the template repo but these actually exist. Do you have an idea what is going wrong here?

huh they must have changed the inclusion rules :/

[asottile]

I'm trying to fix that in #1234 -- we'll see!

[asottile]

ok if you rebase on master it should fix the CI

[asottile]

looks good! can probably squash the commits (if you want, don't need to though and don't feel obligated to)

I'm going to take this for a spin locally and then probably merge (so probably within a few days)!

thanks again for the work on this 🎉