make sure fit_data_scitype is a Tuple

Author: ablaom

src/model_traits.jl

@@ -21,7 +21,7 @@ for M in ABSTRACT_MODEL_SUBTYPES
     @eval(StatisticalTraits.abstract_type(::Type{<:$M}) = $M)
 end
 
-StatisticalTraits.fit_data_scitype(M::Type{<:Model}) = input_scitype(M)
+StatisticalTraits.fit_data_scitype(M::Type{<:Model}) = Tuple{input_scitype(M)}
 StatisticalTraits.fit_data_scitype(::Type{<:Static}) = Tuple{}
 function StatisticalTraits.fit_data_scitype(M::Type{<:Supervised})
     I = input_scitype(M)

test/model_traits.jl

@@ -138,7 +138,7 @@ end
 
     @test fit_data_scitype(P2()) ==
         Tuple{Table(Continuous),AbstractVector{<:Multiclass}}
-    @test fit_data_scitype(U2()) == Table(Continuous)
+    @test fit_data_scitype(U2()) == Tuple{Table(Continuous)}
     @test fit_data_scitype(S2()) == Tuple{}
 end