Well Bangladesh surprised Australia in 2006 1st Test (in the 16 Test win record).
Who says they can't do it to India?
First of all, that was 3 years ago.
Secondly, Australia failed against Mohammad Rafique who (a) is a spinner and (b) is retired.
Causing an upset in Test cricket is a lot harder and requires the luck to go your way 5 days of the week. Bangladesh
shouldn't have a chance in hell, but if they do somehow win, it basically means that India doesn't deserve to be named one of the top teams in world cricket. If you want to be a top team in world cricket, you can't lose to Bangladesh. Australia ended up beating Bangladesh 2-0, even after the luck went against them for most of the match.