.travis.yml

TravisCI flow
1. git clone the repository(where .travis.yml is located) from Github
the option –depth=50 is attached to git clone
2. Move to the cloned repository
3. Get committed code by git checkout
Environment variables written in .travis.yml apply here
4. If you use cache, get cache
5. Specify the version of Ruby to use
6. The one defined in before_install is executed
if you use a cache, it will be added here
7. The one defined in install is executed
8. The one defined in before_script is executed
9. What is defined in script is executed
If the exit code is 0 it is judged as success, otherwise it is judged as failure
10. The one defined in after_success or after_failure is executed.
11. The one defined in after_script is executed

ふむ、工程ごとに分かれたスクリプトを実行するのね。