use pre-commit (lyft#38)

.pre-commit-config.yaml

@@ -0,0 +1,30 @@
+repos:
+    - repo: https://github.com/pre-commit/pre-commit-hooks
+      rev: v2.1.0
+      hooks:
+          - id: check-ast
+          - id: check-docstring-first
+          - id: check-executables-have-shebangs
+          - id: check-json
+          - id: check-merge-conflict
+          - id: check-yaml
+          - id: debug-statements
+          - id: end-of-file-fixer
+          - id: flake8
+            additional_dependencies:
+                - flake8>=3.6.0,<4
+                - flake8-bugbear
+                - flake8-builtins
+                - flake8-comprehensions
+                - flake8-commas
+          - id: trailing-whitespace
+    - repo: https://github.com/asottile/yesqa
+      rev: v0.0.8
+      hooks:
+          - id: yesqa
+            additional_dependencies:
+                - flake8>=3.6.0,<4
+                - flake8-bugbear
+                - flake8-builtins
+                - flake8-comprehensions
+                - flake8-commas

.travis.yml

@@ -1,13 +1,15 @@
 sudo: false
 language: python
 python:
-- '2.7'
 - '3.6'
+cache:
+  directories:
+  - $HOME/.cache/pip
+  - $HOME/.cache/pre-commit
 install:
 - pip install -r requirements.txt
 - pip install -e .
 script: make test
-
 jobs:
   include:
     - stage: deploy

Makefile

@@ -4,5 +4,4 @@ SHELL := /bin/bash
 test: test_lint
 
 test_lint:
-	mkdir -p build
-	set -o pipefail; flake8 | sed "s#^\./##" > build/flake8.txt || (cat build/flake8.txt && exit 1)
+	pre-commit run --all-files --show-diff-on-failure

requirements.txt

@@ -1 +1 @@
-flake8==3.5.0
+pre-commit