It seems the referenced link is currently invalid. Try the following instead:
SAPUI5:
https://sapui5.hana.ondemand.com/sdk/resources/testsuite
OpenUI5:
Question
Using either locally installed openui5-sdk-1.18.10 or here https://openui5.hana.ondemand.com/#resources/testsuite/welcome.html, when trying to access the testsuite, the response is HTTP Status 404 - Resource could not be found!
La solution
It seems the referenced link is currently invalid. Try the following instead:
SAPUI5:
https://sapui5.hana.ondemand.com/sdk/resources/testsuite
OpenUI5: