Add test of custom kernel

Author: devmotion

test/runtests.jl

@@ -12,5 +12,6 @@ include("test_distances.jl")
 include("test_kernels.jl")
 include("test_generic.jl")
 include("test_adjoints.jl")
+include("test_custom.jl")
     #include("types.jl")
 end

test/test_custom.jl

@@ -0,0 +1,26 @@
+using KernelFunctions
+using Test
+
+# minimal definition of a custom kernel
+struct MyKernel <: Kernel{IdentityTransform} end
+
+KernelFunctions.kappa(::MyKernel, d2::Real) = exp(-d2)
+KernelFunctions.metric(::MyKernel) = SqEuclidean()
+KernelFunctions.transform(::MyKernel) = IdentityTransform()
+
+@test kappa(MyKernel(), 3) == kappa(SqExponentialKernel(), 3)
+@test kappa(MyKernel(), 1, 3) == kappa(SqExponentialKernel(), 1, 3)
+@test kappa(MyKernel(), [1, 2], [3, 4]) == kappa(SqExponentialKernel(), [1, 2], [3, 4])
+@test kernelmatrix(MyKernel(), [1 2; 3 4], [5 6; 7 8]) == kernelmatrix(SqExponentialKernel(), [1 2; 3 4], [5 6; 7 8])
+@test kernelmatrix(MyKernel(), [1 2; 3 4]) == kernelmatrix(SqExponentialKernel(), [1 2; 3 4])
+
+# some syntactic sugar
+(κ::MyKernel)(d::Real) = kappa(κ, d)
+(κ::MyKernel)(x::AbstractVector{<:Real}, y::AbstractVector{<:Real}) = kappa(κ, x, y)
+(κ::MyKernel)(X::AbstractMatrix{<:Real}, Y::AbstractMatrix{<:Real}; obsdim = 2) = kernelmatrix(κ, X, Y; obsdim = obsdim)
+(κ::MyKernel)(X::AbstractMatrix{<:Real}; obsdim = 2) = kernelmatrix(κ, X; obsdim = obsdim)
+
+@test MyKernel()(3) == SqExponentialKernel()(3)
+@test MyKernel()([1, 2], [3, 4]) == SqExponentialKernel()([1, 2], [3, 4])
+@test MyKernel()([1 2; 3 4], [5 6; 7 8]) == SqExponentialKernel()([1 2; 3 4], [5 6; 7 8])
+@test MyKernel()([1 2; 3 4]) == SqExponentialKernel()([1 2; 3 4])