tests for enzyme fastpow rule

Author: m-bossart

test/fastpow.jl

@@ -1,4 +1,5 @@
 using DiffEqBase: fastlog2, _exp2, fastpow
+using Enzyme, EnzymeTestUtils
 using Test
 
 @testset "Fast log2" begin
@@ -19,3 +20,23 @@ end
     errors = [abs(^(x, y) - fastpow(x, y)) for x in 0.001:0.001:1, y in 0.08:0.001:0.5]
     @test maximum(errors) < 1e-4
 end
+
+@testset "Fast pow - Enzyme forward rule" begin
+    @testset for RT in (Duplicated, DuplicatedNoNeed),
+        Tx in (Const, Duplicated),
+        Ty in (Const, Duplicated)
+        x = 3.0
+        y = 2.0
+        test_forward(fastpow, RT, (x, Tx), (y, Ty), atol=0.1, rtol=0.1)
+    end
+end
+
+@testset "Fast pow - Enzyme reverse rule" begin
+    @testset for RT in (Active,),
+        Tx in (Active,),
+        Ty in (Active,)
+        x = 2.0
+        y = 3.0
+        test_reverse(fastpow, RT, (x, Tx), (y, Ty))
+    end
+end