Add integration for pre-commit.com (#104)

Fixes #103

.pre-commit-config.yaml

@@ -0,0 +1,19 @@
+# Note: don't use this config for your own repositories. Instead, see
+# "Version control integration" in README.md.
+-   repo: local
+    hooks:
+    - id: black
+      name: black
+      language: system
+      entry: python3 -m black
+      files: ^(black|setup|tests/test_black)\.py$
+    - id: flake8
+      name: flake8
+      language: system
+      entry: flake8
+      files: ^(black|setup|tests/test_black)\.py$
+    - id: mypy
+      name: mypy
+      language: system
+      entry: mypy
+      files: ^(black|setup|tests/test_black)\.py$

.pre-commit-hooks.yaml

@@ -0,0 +1,6 @@
+-   id: black
+    name: black
+    entry: black
+    language: python
+    language_version: python3.6
+    types: [python]

CONTRIBUTING.md

@@ -30,6 +30,7 @@ myself and CentOS at work.
 Install all development dependencies using:
 ```
 $ pipenv install --dev
+$ pre-commit install
 ```
 If you haven't used `pipenv` before but are comfortable with virtualenvs,
 just run `pip install pipenv` in the virtualenv you're already using and
@@ -41,10 +42,6 @@ Before submitting pull requests, run tests with:
 $ python setup.py test
 ```
 
-Also run mypy and flake8 on `black.py` and `test_black.py`.  Travis will
-run all that for you but if you left any errors here, it will be quicker
-and less embarrassing to fix them locally ;-)
-
 
 ## Hygiene
 

Pipfile

@@ -9,6 +9,7 @@ click = "*"
 setuptools = ">=38.6.0"
 
 [dev-packages]
+pre-commit = "*"
 coverage = "*"
 flake8 = "*"
 flake8-bugbear = "*"

Pipfile.lock

@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "51d523fcd093fbf1fd034cd7ad0be9d34dc0fead60b2e23558b4a54f5c0c0ef6"
+            "sha256": "40e1fcca5bf4adcd0e688675714c4b2a771009b6e2005a0f375de1a46a64c906"
         },
         "pipfile-spec": 6,
         "requires": {},
@@ -39,6 +39,13 @@
             ],
             "version": "==0.7.10"
         },
+        "aspy.yaml": {
+            "hashes": [
+                "sha256:6215f44900ff65f27dbd00a36b06a7926276436ed377320cfd4febd69bbd4a94",
+                "sha256:be70cc0ccd1ee1d30f589f2403792eb2ffa7546470af0a17179541b13d8374df"
+            ],
+            "version": "==1.0.0"
+        },
         "attrs": {
             "hashes": [
                 "sha256:1c7960ccfd6a005cd9f7ba884e6316b5e430a3f1a6c37c5f87d8b43f83b54ec9",
@@ -54,6 +61,13 @@
             ],
             "version": "==2.5.3"
         },
+        "cached-property": {
+            "hashes": [
+                "sha256:6e6935ec62567fbcbc346fad84fcea9bc77e3547b7267e62bc5b7ed8e5438ae8",
+                "sha256:a2fa0f89dd422f7e5dd992a4a3e0ce209d5d1e47a4db28fd0a7b5273ec8da3f0"
+            ],
+            "version": "==1.4.0"
+        },
         "certifi": {
             "hashes": [
                 "sha256:14131608ad2fd56836d33a71ee60fa1c82bc9d2c8d98b7bdbc631fe1b3cd1296",
@@ -61,6 +75,13 @@
             ],
             "version": "==2018.1.18"
         },
+        "cfgv": {
+            "hashes": [
+                "sha256:2fbaf8d082456d8fff5a68163ff59c1025a52e906914fbc738be7d8ea5b7aa4b",
+                "sha256:733aa2f66b5106af32d271336a571610b9808e868de0ad5690d9d5155e5960c5"
+            ],
+            "version": "==1.0.0"
+        },
         "chardet": {
             "hashes": [
                 "sha256:84ab92ed1c4d4f16916e05906b6b75a6c0fb5db821cc65e70cbd64a3e2a5eaae",
@@ -148,6 +169,13 @@
             "index": "pypi",
             "version": "==17.8.0"
         },
+        "identify": {
+            "hashes": [
+                "sha256:53be6ea950a5f40e13be2dd87e67413eb6879527b831333196ab2a54de38f499",
+                "sha256:c0bfb29634e04cde8e54aee2d55aff9dad30d6ea1f3e9e3ce731934d78635aa1"
+            ],
+            "version": "==1.0.8"
+        },
         "idna": {
             "hashes": [
                 "sha256:2c6a5de3089009e3da7c5dde64a141dbc8551d5b7f6cf4ed7c2568d0cc520a8f",
@@ -190,6 +218,12 @@
             "index": "pypi",
             "version": "==0.580"
         },
+        "nodeenv": {
+            "hashes": [
+                "sha256:dd0a34001090ff042cfdb4b0c8d6a6f7ec9baa49733f00b695bb8a8b4700ba6c"
+            ],
+            "version": "==1.3.0"
+        },
         "packaging": {
             "hashes": [
                 "sha256:e9215d2d2535d3ae866c3d6efc77d5b24a0192cce0ff20e42896cc0664f889c0",
@@ -204,6 +238,14 @@
             ],
             "version": "==1.4.2"
         },
+        "pre-commit": {
+            "hashes": [
+                "sha256:01bb5f44606735ca30c8be641fa24f5760fcc599a0260ead0067bcde2f0305f9",
+                "sha256:823452163aa9fb024a9ff30947ba7f5a2778708db7554a4d36438b9bbead6bbb"
+            ],
+            "index": "pypi",
+            "version": "==1.8.2"
+        },
         "pycodestyle": {
             "hashes": [
                 "sha256:682256a5b318149ca0d2a9185d365d8864a768a28db66a84a2ea946bcc426766",
@@ -251,6 +293,25 @@
             ],
             "version": "==2018.3"
         },
+        "pyyaml": {
+            "hashes": [
+                "sha256:0c507b7f74b3d2dd4d1322ec8a94794927305ab4cebbe89cc47fe5e81541e6e8",
+                "sha256:16b20e970597e051997d90dc2cddc713a2876c47e3d92d59ee198700c5427736",
+                "sha256:3262c96a1ca437e7e4763e2843746588a965426550f3797a79fca9c6199c431f",
+                "sha256:326420cbb492172dec84b0f65c80942de6cedb5233c413dd824483989c000608",
+                "sha256:4474f8ea030b5127225b8894d626bb66c01cda098d47a2b0d3429b6700af9fd8",
+                "sha256:592766c6303207a20efc445587778322d7f73b161bd994f227adaa341ba212ab",
+                "sha256:5ac82e411044fb129bae5cfbeb3ba626acb2af31a8d17d175004b70862a741a7",
+                "sha256:5f84523c076ad14ff5e6c037fe1c89a7f73a3e04cf0377cb4d017014976433f3",
+                "sha256:827dc04b8fa7d07c44de11fabbc888e627fa8293b695e0f99cb544fdfa1bf0d1",
+                "sha256:b4c423ab23291d3945ac61346feeb9a0dc4184999ede5e7c43e1ffb975130ae6",
+                "sha256:bc6bced57f826ca7cb5125a10b23fd0f2fff3b7c4701d64c439a300ce665fff8",
+                "sha256:c01b880ec30b5a6e6aa67b09a2fe3fb30473008c85cd6a67359a1b15ed6d83a4",
+                "sha256:ca233c64c6e40eaa6c66ef97058cdc80e8d0157a443655baa1b2966e812807ca",
+                "sha256:e863072cdf4c72eebf179342c94e6989c67185842d9997960b3e69290b2fa269"
+            ],
+            "version": "==3.12"
+        },
         "recommonmark": {
             "hashes": [
                 "sha256:6e29c723abcf5533842376d87c4589e62923ecb6002a8e059eb608345ddaff9d",
@@ -304,10 +365,10 @@
         },
         "tqdm": {
             "hashes": [
-                "sha256:05e991ecb0f874046ddcb374396a626afd046fb4d31f73633ea752b844458a7a",
-                "sha256:2aea9f81fdf127048667e0ba22f5fc10ebc879fb838dc52dcf055242037ec1f7"
+                "sha256:4f2eb1d14804caf7095500fe11da0e481a47af912e7b57c93f886ac3c40a49dd",
+                "sha256:91ac47ec2ba6bb92b7ba37706f4dea37019ddd784b22fd279a4b12d93327191d"
             ],
-            "version": "==4.19.8"
+            "version": "==4.20.0"
         },
         "twine": {
             "hashes": [
@@ -346,6 +407,13 @@
                 "sha256:cc44da8e1145637334317feebd728bd869a35285b93cbb4cca2577da7e62db4f"
             ],
             "version": "==1.22"
+        },
+        "virtualenv": {
+            "hashes": [
+                "sha256:1d7e241b431e7afce47e77f8843a276f652699d1fa4f93b9d8ce0076fd7b0b54",
+                "sha256:e8e05d4714a1c51a2f5921e62f547fcb0f713ebbe959e0a7f585cc8bef71d11f"
+            ],
+            "version": "==15.2.0"
         }
     }
 }

README.md

@@ -357,6 +357,28 @@ affect your use case.
 This can be used for example with PyCharm's [File Watchers](https://www.jetbrains.com/help/pycharm/file-watchers.html).
 
 
+## Version control integration
+
+Use [pre-commit](https://pre-commit.com/). Once you [have it
+installed](https://pre-commit.com/#install), add this to the
+`.pre-commit-config.yaml` in your repository:
+```yaml
+repos:
+-   repo: https://github.com/ambv/black
+    rev: stable
+    hooks:
+    - id: black
+      args: [--line-length=88, --safe]
+      python-version: python3.6
+```
+Then run `pre-commit install` and you're ready to go.
+
+`args` in the above config is optional but shows you how you can change
+the line length if you really need to.  If you're already using Python
+3.7, switch the `python-version` accordingly. Finally, `stable` is a tag
+that is pinned to the latest release on PyPI.  If you'd rather run on
+master, this is also an option.
+
 ## Testimonials
 
 **Dusty Phillips**, [writer](https://smile.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=dusty+phillips):