coverage badge

README.md

@@ -1,6 +1,7 @@
 PSR-7 Session
 ===================
 [![Build Status][travis-image]][travis-url]
+[![Coverage Status][coverage-image]][coverage-url]
 
 Alternative to PHP's native session handler. It does not depend on PHP's session capability.
 
@@ -199,3 +200,5 @@ The middleware is compatible with `http-interop/http-middleware` based single pa
 
 [travis-image]: https://travis-ci.org/ojhaujjwal/psr7-session.svg?branch=master
 [travis-url]: https://travis-ci.org/ojhaujjwal/psr7-session
+[coverage-image]: https://coveralls.io/repos/github/ojhaujjwal/psr7-session/badge.svg?branch=master
+[coverage-url]: https://coveralls.io/github/ojhaujjwal/psr7-session?branch=master