adding working atomic addition test

Author: leios

test/atomic_test.jl

@@ -1,18 +1,30 @@
 using KernelAbstractions, Test
 
-@kernel function kernel_atomics(input)
-  I = @index(Global)
-  KernelAbstractions.@atomic input[1] += 1
+# Note: kernels affect second element because some CPU defaults will affect the
+#       first element of a pointer if not specified, so I am covering the bases
+@kernel function atomic_add_kernel(input, b)
+    atomic_add!(pointer(input,2),b) 
 end
 
 function atomics_testsuite(backend)
 
-    @testset "atomic test" begin
-        A = ArrayT{Int}(zeros(64))
+    @testset "atomic addition tests" begin
+        types = [Int32, Int64, UInt32, UInt64, Float32]
+        if ArrayT == CuArray
+            CUDA.capability(CUDA.device()) >= v"6.0" && push!(types, Float64)
+            CUDA.capability(CUDA.device()) >= v"7.0" && push!(types, Float16)
+        else
+            push!(types, Float64)
+            push!(types, Float16)
+        end
 
-        kernel = kernel_atomic(backend(), 4)
-        wait(kernel(ndrange=(length(A),)))
+        for T in types
+            A = ArrayT{T}([0,0])
 
-        @test A[1] == length(A)
+            kernel = atomic_add_kernel(backend(), 4)
+            wait(kernel(A, one(T), ndrange=(1024)))
+
+            @test Array(A)[2] == 1024
+        end
     end
 end