Fix developer tooling for black, flake8

[medmunds]

Several minor fixes and improvements related to addition of black code formatter:

Makefile:

• Add make install-tools target to install development tooling needed for make format and make lint
• Add make develop target that installs tools and test package

README:

• Update Contributing section to use make develop and recommend make format-fix
• Note availability of tox for local testing on all Python versions

Travis.yml:

• Remove accidental duplicate include: that was preventing flake8 job from running
• Add names to flake8 and black jobs ("lint" and "format") to improve build reports

tox.ini:

• Add "format" tox env that runs black
• Change "lint" tox env to use make targets

setup.cfg:

• Update flake8 config with recommended options for black compatibility (but can't change max-line-length yet due to long doc strings)

[medmunds]

(I couldn't tell whether you had intended to keep flake8 alongside black, but guessed "yes" based on flake8 still appearing in the make lint target and an accidentally-disabled Travis job.)

[paulmelnikow]

• Install black in make install, so it is available for make format

• Restore flake8 to make install, so it is available for make lint

Thanks for addressing this in particular. It wasn't possible until #133 was merged and was on my mind to address.

[paulmelnikow]

(I couldn't tell whether you had intended to keep flake8 alongside black, but guessed "yes" based on flake8 still appearing in the make lint target and an accidentally-disabled Travis job.)

Yes, definitely. 😁 They do complementary things.

I usually ignore E203, E302, W503, I201 in the flake8 config to avoid conflicts with black. Not sure if those should be added here at this time.

[medmunds]

Oh, OK, I see a problem. Travis is using make install—but with this PR that would include the developer tooling in the tests, which we don't really want. (Plus it fails on Python 3.5, because black is no longer available there.)

Two options:

• Change Travis's install step to not use make install, but instead just run pip install -e ".[test]"
• Put make install back the way it was, and add a new make develop target that also installs black and flake8 (and update the README Contributing section)

Do you have a preference?

[medmunds]

I usually ignore E203, E302, W503, I201 in the flake8 config to avoid conflicts with black. Not sure if those should be added here at this time.

I just copied the (current) recommended flake8 settings in the black docs. Easy enough to add the others if it would be helpful.

[paulmelnikow]

• Put make install back the way it was, and add a new make develop target that also installs black and flake8 (and update the README Contributing section)

This seems like a good approach to me.

[paulmelnikow]

I just copied the (current) recommended flake8 settings in the black docs. Easy enough to add the others if it would be helpful.

I wonder if W503 is no longer a conflict.

I think E302 and I201 could be left off, too. Those are just my own style preferences.

[medmunds]

Sounds like W503 is now disabled by default in flake8, since a PEP 8 change a while back.

I think I201 depends on flake8-import-order, which we aren't currently using. (I don't think that's included with flake8 by default.)

I have no opinion on E302. (Well, actually, I agree with you, but in the spirit of deferring to opinionated formatting tools, I'm keeping my own opinion to myself :grin:)

[paulmelnikow]

Good to know that I can remove W503 from other projects. Yea, let's add flake8-import-order at some point, and then decide how we feel about all the newlines. I feel like without E302 the imports take up a whole screenful. 😁

[paulmelnikow]

Ready to merge, right?

[medmunds]

Yep!

[paulmelnikow]

Thanks so much! 😁 🚀

[medmunds]

@paulmelnikow my pleasure. Thank you for jumping in as an active maintainer!