Test Coverage on your local box.  run with a single test and see what lines are hit where

adding a profile for this maven plugin.
http://mojo.codehaus.org/cobertura-maven-plugin/index.html

for the Cobertura code coverage tool.
https://github.com/cobertura/cobertura

This should allow you to see while developing test, what lines your new test is covering

in the test-coverage-local profile, update the include section, with the test you want to run.
<include>**/YourTestFileHear.java</include>
use, the test-coverage-local profile, and run maven site.  

this should instrment the classes run you test class and produce a html output report in
hazelcast-client/target/site/cobertura/index.html
hazelcast/target/site/cobertura/index.html
 
an example report from Cobertura 
http://mojo.codehaus.org/cobertura-maven-plugin/sample-maven-shared-io-report/index.html