stderrand the second is its stdout generated up to the point where the error occurredthese are for human (or other toolsinspectionand are automatically removed the next time the tester script runsc:\pp \system\testertype errors\test-errors-runtime err traceback (most recent call last)file \scripts\test-errors-runtime py"line in print( zerodivisionerrorint division or modulo by zero :\pp \system\testertype outputs\test-errors-runtime out bad starting nowwhen run again without making any changes to the teststhe test driver script compares saved prior outputs to new ones and detects no regressionsfailures designated by exit status and stderr messages are still reported as beforebut there are no deviations from other testssaved expected outputc:\pp \system\testerpython tester py start testermon feb : : in :\users\mark\stuff\books\ \pp \dev\examples\pp \system\tester passedtest-basic-args py passedtest-basic-stdout py passedtest-basic-streams py passedtest-basic-this py error statustest-errors-runtime py error streamtest-errors-runtime py \errors\test-errors-runtime err error statustest-errors-syntax py error streamtest-errors-syntax py \errors\test-errors-syntax err error statustest-status-bad py passedtest-status-good py finishedmon feb : : tests were run tests failed but when make change in one of the test scripts that will produce different output ( changed loop counter to print fewer lines)the regression is caught and reportedthe new and different output of the script is reported as failureand saved in outputs as badfor later viewingc:\pp \system\testerpython tester py start testermon feb : : in :\users\mark\stuff\books\ \pp \dev\examples\pp \system\tester passedtest-basic-args py failed outputtest-basic-stdout py \outputs\test-basic-stdout out bad passedtest-basic-streams py passedtest-basic-this py error statustest-errors-runtime py error streamtest-errors-runtime py \errors\test-errors-runtime err error statustest-errors-syntax py error streamtest-errors-syntax py \errors\test-errors-syntax err error statustest-status-bad py passedtest-status-good py finishedmon feb : : complete system programs