what is pre commit looks like and how to implement it

The pre-commit can find and fix common issues before changes are submitted for code review;

Code reviewers should pay attention to the architecture of a change and not worry about trivial errors like syntax error, not following code style, test missing.

How to implement pre-commit [TL;DR]

1. write a python script(pre-commit.py) to check all the checkable files and print error messages;
   1. get all committed files;
   2. filter with exclude files;
   3. split files into .py, .js and .html;
   4. check with customize pep8, pylint, isort, jshint, jscs etc;
   5. commit continue if all check pass, else we will have more details in report file.
2. write a shell script(pre_commit)(name should not change) which actually called by git command;
   1. active the specific env(which create by step 3);
   2. execute the real checker script.
3. write another shell script(install_pre_commit.sh) to install pre-commit;
   1. make a independent env with virtualenv;
   2. install third libs in this env, such as pep8, pylint, isort etc(make sure they have specific version number);
   3. copy the pre_commit shell script to git directory and make it executable.

Actually you should not reinvent the wheel

1. pip install pre-commit;
2. pre-commit install;
3. create file .pre-commit-hooks.yaml at the root of your repo and configure your hooks.

the simplest hooks configuration like this:

- repo: git://github.com/pre-commit/pre-commit-hooks
  sha: v0.4.2
  hooks:
  - id: trailing-whitespace

additional information

• Out of box hooks
• How to create custom hooks
• Tutorial