ConfigurationManagerTest is not being found on your classpath. Ensure that the ConfigurationManagerTest.class file is available on your classpath.
It might not exist if it wasn’t successfully compiled or if it’s being created in a directory that you haven’t told the Eclipse project should be on the classpath.
Assuming that you’ve put your test classes in a separate folder, make sure that it shows up in the “Package Explorer” view (rather than the “Navigator” view).
Under the project properties, “Java Build Path” and the “Source” tab, you can also see if the source folder is included for building as well as where the .class files are generated.