First, in your actual code, it should be Map<String, Object>, as no other types of keys are valid in JSON. Next, you just need to deserializeUntyped:
List<Object> selectedRows = (List<Object>)JSON.deserializeUntyped(
And pass that in as the ...
Goto setup -> Develop -> Apex Test Execution and click the Options button.
Make sure "Store Only Aggregated Code Coverage" is UNCHECKED
Not showing Test code coverage on developer console