I've been tasked to identify gaps in the regression test coverage of a large C# based data management system that comprises a SQL database, server application, multiple web clients and multiple windows forms clients as well as a SOAP based web service API.
There are a large number of manual black-box regression tests that have evolved over the 15+ years this system has been evolving but there are gaps in the coverage. We are in process of automating these test cases with Selenium and White based test frameworks.
I wonder if anyone can suggest a good analysis technique to identify the gaps in coverage.
I'm also keen not to duplicate existing white-box integration test coverage of business logic when we come to automate the ~150 manual regression test scripts.