feat: add test cases

[xuexb]

No description provided.

[coveralls]

Changes Unknown when pulling 42f2234 on feat/test into ** on master**.

[xuexb]

@yugasun 老铁有个 eslint 报错：

/home/travis/build/xuexb/github-bot/src/github.js
  288:35  error  Identifier 'tag_name' is not in camel case          camelcase
  288:45  error  Identifier 'target_commitish' is not in camel case  camelcase
  317:37  error  Identifier 'tag_name' is not in camel case          camelcase
  342:52  error  Identifier 'team_reviewers' is not in camel case    camelcase

[yugasun]

@xuexb 看到了，我把你修复吧。

[coveralls]

Changes Unknown when pulling 06bfb13 on feat/test into ** on master**.

[coveralls]

Changes Unknown when pulling 551a327 on feat/test into ** on master**.

[coveralls]

Changes Unknown when pulling 40d9547 on feat/test into ** on master**.

[yugasun]

@xuexb 你这个PR线上改的太难受了，o(╯□╰)o，等合入master后，我直接修改eslint规则，禁用 camelcase。