Does anyone seriously think that Russia was over-flying Turkey (if at all) to test its defences? Arse. Turkey has been playing a double game with ISIS and the other Syrian rebels for years now. Islamafascists, have been dobbing in and out across the border with Turkey's connivance for the duration of this 'war'.
Russia are not the good guys in all this dirty war - but neither, ffs, are Turkey. ISIS could have been wiped out years ago, had Turkey REALLY wanted it. Well. wipe them out now, hold our noses and put Assad back in (wish we'd have left Saddam alone, tbh) and then ask ourselves just whose side is Turkey REALLY on, when push comes to shove?
Alternatively, just leave the whole Middle-East to get on with it. Hopefully the Saudis will get their's in that conflagration. I trust them less than I trust the Turks.