Selective Regression Tests in Early Warning System

Regression test selection based on procedure level code coverage of the changes will be applied to EWS. See the description of the selection method, meta-bug and patches at SelectiveTestBuildBot.

Before introducing it to the ​official EWS we plan to make some tests for its reliability and efficiency. The test system is available at: ​http://qt-ews.appspot.com/queue-status/qt-st-ews

The test system is modified so that it executes both the full and the selective test on the patch. First the test selection is performed based on the changes in the patch and using the coverage database, and if it returns a non-trivial selection (not 0 and not all the tests), then the full test is executed on the same patch. The system returns always with a failure so that we can examine the build logs to verify the correctness.