unikernel/duniverse/ppxlib/test/driver/instrument/dune

@@ -0,0 +1,14 @@
+(rule
+ (package ppxlib)
+ (alias runtest)
+ (enabled_if
+  (>= %{ocaml_version} "4.08.0"))
+ (deps
+  (:test test.ml)
+  (package ppxlib))
+ (action
+  (chdir
+   %{project_root}
+   (progn
+    (run expect-test %{test})
+    (diff? %{test} %{test}.corrected)))))

unikernel/duniverse/ppxlib/test/driver/instrument/test.ml

@@ -0,0 +1,36 @@
+open Ppxlib
+
+let extend_list_by name = object
+  inherit Ast_traverse.map as super
+
+  method! expression e =
+    match e.pexp_desc with
+    | Pexp_construct ({txt = Lident "[]"; _}, None) -> Ast_builder.Default.elist ~loc:e.pexp_loc [Ast_builder.Default.estring ~loc:e.pexp_loc name]
+    | _ -> super#expression e
+end
+[%%expect{|
+val extend_list_by : string -> Ast_traverse.map = <fun>
+|}]
+
+let () =
+  let name = "a: instr pos=Before" in
+  let transform = extend_list_by name in
+  Driver.(register_transformation ~instrument:(Instrument.make ~position:Before transform#structure) name)
+
+let () =
+  let name = "b: instr pos=After" in
+  let transform = extend_list_by name in
+  Driver.(register_transformation ~instrument:(Instrument.make ~position:After transform#structure) name)
+
+let () =
+  let name = "c: impl" in
+  let transform = extend_list_by name in
+  Driver.register_transformation ~impl:transform#structure name
+
+(* The order of the list should only depend on how the rewriters got registered,
+   not on the alphabetic order of the names they got registered with. *)
+let x = []
+[%%expect{|
+val x : string list =
+  ["a: instr pos=Before"; "c: impl"; "b: instr pos=After"]
+|}]