Export and add test

Author: sharanry

src/kernels/constant.jl

@@ -24,6 +24,7 @@ Kernel function working as an equivalent to add white noise.
 struct WhiteKernel <: BaseKernel end
 
 const EyeKernel = WhiteKernel
+export EyeKernel
 
 kappa(κ::WhiteKernel,δₓₓ::Real) = δₓₓ
 

test/test_kernels.jl

@@ -16,6 +16,7 @@ x = rand()*2; v1 = rand(3); v2 = rand(3); id = IdentityTransform()
             @test eltype(k) == Any
             @test kappa(k,1.0) == 1.0
             @test kappa(k,0.0) == 0.0
+            @test EyeKernel == WhiteKernel
         end
         @testset "ConstantKernel" begin
             c = 2.0