Add a check_cuda macro for unit tests

Added @/check_cuda, a macro that checks CUDA.functional() before running
CUDA-related unit tests. If CUDA is not detected on the system, it emits
a warning before continuing with other unit tests.

Author: kernelmethod

test/runtests.jl

@@ -1,5 +1,7 @@
 using ChaChaCiphers, Documenter, Test
 
+include("utils.jl")
+
 include("test_core.jl")
 include("test_chacha.jl")
 include("test_keystream.jl")

test/test_chacha.jl

@@ -173,7 +173,7 @@ using Test
 end
 
 @testset "CUDA ChaCha tests" begin
-    if CUDA.functional()
+    @check_cuda begin
         @testset "Test quarter-round function" begin
             # Ref: IETF RFC 8439, Sec. 2.1.1
             # https://datatracker.ietf.org/doc/html/rfc8439#section-2.1.1

test/test_cuda_keystream.jl

@@ -8,7 +8,7 @@ using Statistics
 using Test
 
 @testset "CUDAChaChaStream tests" begin
-    if CUDA.functional()
+    @check_cuda begin
         @testset "Construct CUDAChaChaStream" begin
             rng = CUDAChaCha12Stream()
             @test rng.doublerounds == 6
@@ -85,7 +85,5 @@ using Test
 
             @test rand_gpu == rand_cpu
         end
-    else
-        @warn "CUDA.functional() = false; skipping tests"
     end
 end

test/utils.jl

@@ -0,0 +1,13 @@
+# Testing utilities
+
+macro check_cuda(expr)
+    quote
+        import CUDA
+
+        if CUDA.functional()
+            $(esc(expr))
+        else
+            @warn "CUDA.functional() = false; skipping tests"
+        end
+    end
+end