update Readme

Author: Dan Richelson

README.md

@@ -67,6 +67,11 @@ Using Redis
 
     $client = new LaunchDarkly\LDClient("your_sdk_key", ['feature_requester_class' => 'LaunchDarkly\LDDFeatureRequester']);
 
+Testing
+-------
+
+We run integration tests for all our SDKs using a centralized test harness. This approach gives us the ability to test for consistency across SDKs, as well as test networking behavior in a long-running application. These tests cover each method in the SDK, and verify that event sending, flag evaluation, stream reconnection, and other aspects of the SDK all behave correctly.
+
 Learn more
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