Merge pull request #1308 from SciML/ChrisRackauckas-patch-3-1

Fix NullParameter get_unit handling

Author: ChrisRackauckas

src/systems/validation.jl

@@ -42,7 +42,7 @@ get_unit(x::Literal) = screen_unit(getmetadata(x,VariableUnit, unitless))
 get_unit(op::Differential, args) = get_unit(args[1]) / get_unit(op.x)
 get_unit(op::Difference, args) =   get_unit(args[1]) / get_unit(op.t)
 get_unit(op::typeof(getindex),args) = get_unit(args[1])
-get_unit(x::typeof(SciMLBase.NullParameters)) = unitless
+get_unit(x::SciMLBase.NullParameters) = unitless
 
 function get_unit(op,args) # Fallback
     result = op(1 .* get_unit.(args)...)

test/units.jl

@@ -16,7 +16,7 @@ D = Differential(t)
 @test MT.get_unit(τ) == u"ms"
 @test MT.get_unit(γ) == MT.unitless
 @test MT.get_unit(0.5) == MT.unitless
-@test MT.get_unit(MT.SciMLBase.NullParameters) == MT.unitless
+@test MT.get_unit(MT.SciMLBase.NullParameters()) == MT.unitless
 
 # Prohibited unit types
 @parameters β [unit = u"°"] α [unit = u"°C"] γ [unit = 1u"s"]