Document how to run the test suite

References #40.

README.md

@@ -99,6 +99,24 @@ Elastisch is part of the group of [Clojure libraries](http://clojurewerkz.org) k
 and several others.
 
 
+## Running Tests
+
+To run Elastisch tests, make sure you have ElasticSearch running. It must be the same
+version that Elastisch depends on due to binary protocol changes between releases.
+[project.clj](project.clj) or [project page on Clojars](https://clojars.org/clojurewerkz/elastisch)
+can help find that out.
+
+Next you need to have `ES_CLUSTER_NAME` exported to something unique. Again, this is
+an ElasticSearch binary client requirement.
+
+Finally, run the tests as
+
+    lein all test
+
+To run only HTTP client tests, use
+
+    lein all test :ci
+
 ## Continuous Integration
 
 [![Continuous Integration status](https://secure.travis-ci.org/clojurewerkz/elastisch.png)](http://travis-ci.org/clojurewerkz/elastisch)