Some automated regression test scripts run by a TAS in a given test environment make calls to private APIs that require authentication for all requests (the authentication method is the same for all APIs). The SUT is a business-critical system. The following two changes are planned: a change in the authentication method of all APIs and a minor upgrade of the OS (Operating System) in the test environment. You have updated the test scripts to cope with the change in the API authentication method. Which of the following sequences of activities is BEST to ensure that the test scripts are not adversely affected by these changes?
First upgrade the OS, then implement the change in the API authentication method, and finally run all the updated test scripts
Implement one change at a time and run a subset of the updated test scripts after each change, and finally run all the
updated test scripts
First implement the change in the API authentication method, then upgrade the OS, and finally run all the
Implement one change at a time and run a subset of the updated test scripts after each change