Add ForwardDiffExt tests back

Author: penelopeysm

test/ext/DynamicPPLForwardDiffExt.jl

@@ -0,0 +1,32 @@
+module DynamicPPLForwardDiffExtTests
+
+using DynamicPPL
+using ADTypes: AutoForwardDiff
+using ForwardDiff: ForwardDiff
+using Distributions: MvNormal
+using LinearAlgebra: I
+using Test: @test, @testset
+
+# get_chunksize(ad::AutoForwardDiff{chunk}) where {chunk} = chunk
+
+@testset "ForwardDiff tweak_adtype" begin
+    MODEL_SIZE = 10
+    @model f() = x ~ MvNormal(zeros(MODEL_SIZE), I)
+    model = f()
+    varinfo = VarInfo(model)
+    context = DefaultContext()
+
+    @testset "Chunk size setting" for chunksize in (nothing, 0)
+        base_adtype = AutoForwardDiff(; chunksize=chunksize)
+        new_adtype = DynamicPPL.tweak_adtype(base_adtype, model, varinfo, context)
+        @test new_adtype isa AutoForwardDiff{MODEL_SIZE}
+    end
+
+    @testset "Tag setting" begin
+        base_adtype = AutoForwardDiff()
+        new_adtype = DynamicPPL.tweak_adtype(base_adtype, model, varinfo, context)
+        @test new_adtype.tag isa ForwardDiff.Tag{DynamicPPL.DynamicPPLTag}
+    end
+end
+
+end

test/runtests.jl

@@ -75,6 +75,7 @@ include("test_util.jl")
             include("ext/DynamicPPLJETExt.jl")
         end
         @testset "ad" begin
+            include("ext/DynamicPPLForwardDiffExt.jl")
             include("ext/DynamicPPLMooncakeExt.jl")
             include("ad.jl")
         end