Adding an optional parameter to to_string to end with a newline

Signed-off-by: Paul-Elliot <[email protected]>

lib/write.ml

@@ -460,10 +460,12 @@ let to_output ?buf ?(len=4096) ?std out x =
   out#output (Buffer.contents ob) 0 (Buffer.length ob);
   ()
 
-let to_file ?len ?std file x =
+let to_file ?len ?std ?(newline = true) file x =
   let oc = open_out file in
   try
     to_channel ?len ?std oc x;
+    if newline then
+      output_string oc "\n";
     close_out oc
   with e ->
     close_out_noerr oc;

lib/write.mli

@@ -48,9 +48,12 @@ val to_output :
 val to_file :
   ?len:int ->
   ?std:bool ->
+  ?newline:bool ->
   string -> t -> unit
   (** Write a compact JSON value to a file.
-      See [to_string] for the role of the optional arguments. *)
+      See [to_string] for the role of the optional arguments.
+      @param newline whether to end the content of the file with a new line.
+      Optional parameter with value [true] by default. *)
 
 val to_buffer :
   ?std:bool ->

test/test_write.ml

@@ -11,7 +11,7 @@ let to_file () =
     close_in ic;
     s
   in
-  Alcotest.(check string) __LOC__ Fixtures.json_string file_content;
+  Alcotest.(check string) __LOC__ (Fixtures.json_string ^ "\n") file_content;
   Sys.remove output_file
 
 let single_json = [