test: add tests

Author: avik-pal

src/ConcreteRArray.jl

@@ -366,13 +366,9 @@ function Base.fill!(a::ConcreteRArray{T,N}, val) where {T,N}
         buf = a.data.buffer
         GC.@preserve buf begin
             ptr = Base.unsafe_convert(Ptr{T}, XLA.UnsafeBufferPointer(buf))
-            start = 0
-            for i in 1:N
-                start *= size(a, N - i + 1)
-                start += (args[N - i + 1] - 1)
+            for start in 0:(length(a) - 1)
+                unsafe_store!(ptr, val, start)
             end
-            start += 1
-            unsafe_store!(ptr, val, start)
         end
         return a
     end

test/basic.jl

@@ -664,3 +664,15 @@ end
         ifelse(ConcreteRNumber(false), ConcreteRNumber(1.0f0), ConcreteRNumber(0.0f0))
     ) isa ConcreteRNumber{Float32}
 end
+
+@testset "fill! and zero on ConcreteRArray" begin
+    x_ra = Reactant.to_rarray(rand(3, 4))
+
+    z = zero(x_ra)
+    @test z isa ConcreteRArray
+    @test size(z) == size(x_ra)
+    @test all(iszero, Array(z))
+
+    fill!(z, 1.0)
+    @test all(==(1.0), Array(z))
+end