All they need is a couple of red ball games to be available for test matches Rashid as shown in white ball England need him to play he's a wicket taker after all who's the other frontline spinner besides Ali to turn it for England.
We've tried Rashid as a Test player and he proved ineffective in the longer format though.
It's all well and good picking up a few poles in a white ball game where the batsman have to go after you, but in Test matches batsman can afford to wait and hit the bad balls (of which Rashid bowls a fair few) without the pressure of needing to go after him from the get go.
Considering he's played 10 Tests (in spin friendly conditions) his average of 42 likely reflects fairly on him.
As for other frontline spinners:
Jack Leach?
Dom Bess?