update readme & add code coverage test

Author: BruceZhang1993

.gitignore

@@ -7,3 +7,4 @@ __pycache__
 *.egg-info
 /.eggs
 /.pytest_cache
+coverage.xml

.travis.yml

@@ -38,10 +38,13 @@ cache:
     - .pytest_cache
 install:
   - pip3 install pytest
+  - pip3 install pytest-cov
+  - pip3 install codacy-coverage
   - pip3 install --upgrade pip
   - pip3 install -r requirements.txt
 script:
-  - pytest -v
+  - pytest -v --cov --cov-report xml
+  - python-codacy-coverage
 before_deploy:
   - python3 setup.py bdist_wheel || python setup.py bdist_wheel
 deploy:

README.md

@@ -5,6 +5,8 @@ Yet another python index generator
 [![Travis](https://img.shields.io/travis/BruceZhang1993/index-generator.svg?style=for-the-badge)](https://travis-ci.org/BruceZhang1993/index-generator)
 [![GitHub top language](https://img.shields.io/github/languages/top/BruceZhang1993/index-generator.svg?style=for-the-badge)](https://github.com/BruceZhang1993/index-generator)
 [![Requires.io](https://img.shields.io/requires/github/BruceZhang1993/index-generator.svg?style=for-the-badge)](https://requires.io/github/BruceZhang1993/index-generator/requirements/?branch=master)
+[![GitHub](https://img.shields.io/github/license/BruceZhang1993/index-generator.svg?style=for-the-badge)](https://github.com/BruceZhang1993/index-generator/blob/master/LICENSE)
+![Codacy grade](https://img.shields.io/codacy/grade/3aef89bd80514ba0a2e353aefac47ebe.svg?style=for-the-badge)
 
 ## Install