Add pre-commit config

This adds a configuration for the pre-commit framework, a simple way to
manage, install and run git hooks to catch common problems early on. See
https://pre-commit.com/ for details.

This adds the following hooks:

- check-case-conflict
- check-byte-order-marker
- check-yaml
- check-json
- check-xml
- mixed-line-ending
- end-of-file-fixer
- trailing-whitespace
- no-commit-to-branch
- eslint
- clang-format
- qsscheck

If you have python and python-pip installed, just run:

    $ pip install --user pre-commit
    $ git clone https://github.com/mixxxdj/mixxx.git
    $ cd mixxx
    $ pre-commit install
    $ pre-commit install -t pre-push

It will now run relevant hooks automatically on every `git commit` or
`git push` in the mixxx git repository.

If you have a problems with a particular hook, you can use the `$SKIP`
environment variable to disable hooks:

    $ SKIP=clang-format,end-of-file-fixer git commit

This can also be used to separate logic changes and autoformatting into
two subsequent commits.

Using the `$SKIP` var is preferable to using `git commit --no-verify`
because it won't prevent catching other, unrelated issues.

1 files changed, 53 insertions, 0 deletions

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
new file mode 100644
index 0000000000..3f5459f593
--- /dev/null
+++ b/.pre-commit-config.yaml
@@ -0,0 +1,53 @@
+repos:
+- repo: https://github.com/pre-commit/pre-commit-hooks
+  rev: v2.3.0
+  hooks:
+  - id: check-case-conflict
+  - id: check-byte-order-marker
+  - id: check-yaml
+  - id: check-json
+  - id: check-xml
+  - id: mixed-line-ending
+  - id: end-of-file-fixer
+    stages:
+    - commit
+    - manual
+  - id: trailing-whitespace
+    stages:
+    - commit
+    - manual
+  - id: no-commit-to-branch
+- repo: https://github.com/pre-commit/mirrors-eslint
+  rev: v6.8.0
+  hooks:
+  - id: eslint
+    args: [--fix]
+    additional_dependencies:
+    - eslint@6.8.0
+    stages:
+    - commit
+    - manual
+- repo: git://github.com/doublify/pre-commit-clang-format
+  rev: master
+  hooks:
+  - id: clang-format
+    stages:
+    - commit
+    - manual
+- repo: local
+  hooks:
+  - id: qsscheck
+    name: qsscheck
+    description: Run qsscheck to detect broken QSS.
+    entry: ./scripts/qsscheck.py
+    args: [.]
+    pass_filenames: false
+    language: python
+    additional_dependencies:
+    - tinycss==0.4
+    types: [text]
+    files: ^.*\.qss$
+    stages:
+    - commit
+    - push
+    - manual