Independently of whether you have unit tests in your solution or not, dotCover allows you to analyze code coverage for manual test sessions. After running a manual test session under control of dotCover, you wil get a coverage snapshot with statement coverage of the session. Using the data in this snapshot, you can get down to the source code of the tested application and see what parts of the code were called during the session and what was not reached.
There are two ways to run applications under control of dotCover:
Same as for unit tests, statement coverage here does not guarantee that the covered statements contain no errors. However, these data will help you analyze your testing scenarios and target the unreached parts of code in new scenarios.