Fix similarterm with Pow

Author: YingboMa

src/types.jl

@@ -954,7 +954,7 @@ function similarterm(p::NumericTerm, f, args, T=nothing; metadata=nothing)
     elseif f == (*)
         Mul(T, makemul(1, args...)...; metadata=metadata)
     elseif f == (^) && length(args) == 2
-        Pow{T, typeof.(args)...}(args...; metadata=metadata)
+        Pow{T}(makepow(args...)...; metadata=metadata)
     else
         Term{T}(f, args; metadata=metadata)
     end

test/basics.jl

@@ -166,9 +166,10 @@ end
     @test repr((-1)^a) == "(-1)^a"
 end
 
-@testset "similarterm with Add" begin
+@testset "similarterm" begin
     @syms a b c
     @test isequal(SymbolicUtils.similarterm((b + c), +, [a,  (b+c)]).dict, Dict(a=>1,b=>1,c=>1))
+    @test isequal(SymbolicUtils.similarterm(b^2, ^, [b^2,  1//2]), b)
 end
 
 toterm(t) = Term{symtype(t)}(operation(t), arguments(t))