test: cover Optim extension error path

Author: MilesCranmerBot

ext/DynamicExpressionsOptimExt.jl

@@ -91,19 +91,15 @@ function wrap_func(
 end
 
 const _INPLACEOBJECTIVE_SPEC_V8 = (
-    fields = (:fdf, :fgh, :hvp, :fghvp, :fjvp),
-    x_last = (:fdf, :fgh),
-    xv_tail = (:hvp, :fghvp, :fjvp),
+    fields=(:fdf, :fgh, :hvp, :fghvp, :fjvp),
+    x_last=(:fdf, :fgh),
+    xv_tail=(:hvp, :fghvp, :fjvp),
 )
 const _INPLACEOBJECTIVE_SPEC_V7 = (
-    fields = (:df, :fdf, :fgh, :hv, :fghv),
-    x_last = (:df, :fdf, :fgh),
-    xv_tail = (:hv, :fghv),
+    fields=(:df, :fdf, :fgh, :hv, :fghv), x_last=(:df, :fdf, :fgh), xv_tail=(:hv, :fghv)
 )
 const _INPLACEOBJECTIVE_SPEC_OLD = (
-    fields = (:fdf, :fgh, :hv, :fghv),
-    x_last = (:fdf, :fgh),
-    xv_tail = (:hv, :fghv),
+    fields=(:fdf, :fgh, :hv, :fghv), x_last=(:fdf, :fgh), xv_tail=(:hv, :fghv)
 )
 
 @inline function _wrap_inplaceobjective_field(
@@ -141,7 +137,8 @@ function wrap_func(
     #
     # We use `@static` branching so that only the relevant layout for the *installed*
     # NLSolversBase version is compiled/instrumented.
-    @static if fieldnames(NLSolversBase.InplaceObjective) == _INPLACEOBJECTIVE_SPEC_V8.fields
+    @static if fieldnames(NLSolversBase.InplaceObjective) ==
+        _INPLACEOBJECTIVE_SPEC_V8.fields
         # NLSolversBase v8 / Optim v2
         return _wrap_inplaceobjective(f, tree, refs, _INPLACEOBJECTIVE_SPEC_V8)
     elseif fieldnames(NLSolversBase.InplaceObjective) == _INPLACEOBJECTIVE_SPEC_V7.fields

test/test_optim.jl

@@ -206,3 +206,31 @@ end
     wrapped = ext._wrap_objective_xv_tail((args...) -> nothing, tree, refs)
     @test_throws ArgumentError wrapped(x0)
 end
+
+@testitem "Wrap InplaceObjective: error on unknown field" begin
+    using DynamicExpressions, Optim
+    include("test_optim_setup.jl")
+
+    ext = Base.get_extension(DynamicExpressions, :DynamicExpressionsOptimExt)
+
+    tree = copy(original_tree)
+    _, refs = get_scalar_constants(tree)
+
+    # Construct a dummy InplaceObjective for the *installed* NLSolversBase/Optim
+    # layout, then directly hit the internal error branch.
+    fields = fieldnames(Optim.NLSolversBase.InplaceObjective)
+    dummy = (args...) -> nothing
+    obj = Optim.NLSolversBase.InplaceObjective((dummy for _ in fields)...)
+
+    spec = if fields == ext._INPLACEOBJECTIVE_SPEC_V8.fields
+        ext._INPLACEOBJECTIVE_SPEC_V8
+    elseif fields == ext._INPLACEOBJECTIVE_SPEC_V7.fields
+        ext._INPLACEOBJECTIVE_SPEC_V7
+    else
+        ext._INPLACEOBJECTIVE_SPEC_OLD
+    end
+
+    @test_throws ArgumentError ext._wrap_inplaceobjective_field(
+        Val(:__unknown_field__), obj, tree, refs, spec
+    )
+end