Add execution test

src/code_gen/main.jl

@@ -57,14 +57,13 @@ Execute the given generated_code (as returned by [`gen_code`](@ref)) on the give
 """
 function execute(generated_code, input::Dict{ParticleType, Vector{Particle}})
     (code, inputSymbols, outputSymbol) = generated_code
-    @assert length(input) == length(inputSymbols)
 
     assignInputs = Vector{Expr}()
     for (name, symbol) in inputSymbols
         type = nothing
-        if startswith("A", name)
+        if startswith(name, "A")
             type = A
-        elseif startswith("B", name)
+        elseif startswith(name, "B")
             type = B
         else
             type = C