I create a text file as a report log.
What I usually do is as the tests are running:
+ Open the text file
+ Add logging information (e.g. TestCase001: Login with valid credentials : Status = PASS)
+ Meanwhile I also keep a count of total test cases, passed/failed test cases and incomplete test cases in the Project.Variables
+ At the end I log that information in the report log text file.
e.g.
Total Tests Run : 120
Pass/Fail Ratio : 99/21
Total Test Execution Time : 00:38:12
All scripting languages provide great support for writing to text file. You can also choose to output in a csv format and then submit it as an Excel report