Allow expect_tests to be DCE by jsoo ..

runtime/ppx_expect_runtime.ml

@@ -35,3 +35,5 @@ module Write_corrected_file = Write_corrected_file
 module Make_test_block = Test_block.Make
 module For_external = Test_block.For_external
 module For_apply_style = Test_spec.For_apply_style
+
+let tests_should_run = Test_block.tests_should_run

runtime/test_block.ml

@@ -159,6 +159,14 @@ module Configured (C : Expect_test_config_types.S) = struct
   ;;
 end
 
+let tests_should_run =
+  try
+    ignore (Stdlib.Sys.getenv "FORCE_DROP_INLINE_TEST" : string);
+    false
+  with
+  | Not_found -> true
+;;
+
 (* The expect test currently being executed and some info we print if the program
    crashes in the middle of a test. *)
 module Current_test : sig

runtime/test_block.mli

@@ -101,6 +101,8 @@ module For_external : sig
     -> bool
 end
 
+val tests_should_run : bool
+
 (** Action to perform when exiting from a program that runs expect tests. Alerts of
     runtime failure if the program exited while executing an expect test. *)
 val at_exit : unit -> unit

src/ppx_expect.ml

@@ -250,6 +250,7 @@ let transform_let_expect ~trailing_location ~tags ~expected_exn ~description ~lo
     match Ppx_inline_test_lib.testing with
     | `Not_testing -> ()
     | `Testing _ ->
+      if Ppx_expect_runtime.tests_should_run then
       let module Ppx_expect_test_block =
         Ppx_expect_runtime.Make_test_block [@alert "-ppx_expect_runtime"]
           (Expect_test_config)