a6b3b70278
Test legacy tether/untether API behavior. tether() rely on downstream setup ready for tethering. Currently the only user is bluetooth tethering. For other tetherings, there is no guaranteed that calling tether() can always switch given interface to tethered. Tethering may callback with onError depend on the interface status. Caller should use startTethering/stopTethering API instead of these legacy APIs. This change also change the precondition verification of startTethering. If tethering interface got error last time, such interface would not be reported as tetherable. Bug: 150632712 Test: atest CtsTetheringTest Change-Id: Ifb3a0618208ffd0ff224c60f377036bc22ba0565 Merged-In: Ifb3a0618208ffd0ff224c60f377036bc22ba0565