generate dune diff rules in examples/

- Generating the diff rules using a helper program should make it
  easier to add new examples.

src/examples/dune

@@ -4,16 +4,6 @@
  (action
   (run ocaml-protoc --binary --pp --ml_out ./ %{deps})))
 
-(rule
- (alias runtest)
- (action
-  (diff example01.ml.expected example01.ml)))
-
-(rule
- (alias runtest)
- (action
-  (diff example01.mli.expected example01.mli)))
-
 (test
  (name example01)
  (modules t_example01 example01)
@@ -26,16 +16,6 @@
  (action
   (run ocaml-protoc --pp --ml_out ./ %{deps})))
 
-(rule
- (alias runtest)
- (action
-  (diff example03.ml.expected example03.ml)))
-
-(rule
- (alias runtest)
- (action
-  (diff example03.mli.expected example03.mli)))
-
 (test
  (name example03)
  (modules t_example03 example03)
@@ -48,16 +28,6 @@
  (action
   (run ocaml-protoc --pp --ml_out ./ %{deps})))
 
-(rule
- (alias runtest)
- (action
-  (diff example04.ml.expected example04.ml)))
-
-(rule
- (alias runtest)
- (action
-  (diff example04.mli.expected example04.mli)))
-
 (test
  (name example04)
  (modules t_example04 example04)
@@ -70,16 +40,6 @@
  (action
   (run ocaml-protoc --binary --pp --ml_out ./ %{deps})))
 
-(rule
- (alias runtest)
- (action
-  (diff example05.ml.expected example05.ml)))
-
-(rule
- (alias runtest)
- (action
-  (diff example05.mli.expected example05.mli)))
-
 (test
  (name example05)
  (modules t_example05 example05)
@@ -92,16 +52,6 @@
  (action
   (run ocaml-protoc --binary --pp --yojson --services --ml_out ./ %{deps})))
 
-(rule
- (alias runtest)
- (action
-  (diff calculator.ml.expected calculator.ml)))
-
-(rule
- (alias runtest)
- (action
-  (diff calculator.mli.expected calculator.mli)))
-
 (test
  (name calculator)
  (modules t_calculator calculator)
@@ -114,16 +64,6 @@
  (action
   (run ocaml-protoc --binary --pp --yojson --services --ml_out ./ %{deps})))
 
-(rule
- (alias runtest)
- (action
-  (diff file_server.ml.expected file_server.ml)))
-
-(rule
- (alias runtest)
- (action
-  (diff file_server.mli.expected file_server.mli)))
-
 (test
  (name file_server)
  (modules file_server) ; just check that it compiles
@@ -136,18 +76,31 @@
  (action
   (run ocaml-protoc --pp --binary --ml_out ./ %{deps})))
 
+(test
+ (name orgchart_ml)
+ (modules orgchart orgchart_ml)
+ (package ocaml-protoc)
+ (libraries pbrt))
+
+(include dune.inc)
+
 (rule
  (alias runtest)
  (action
-  (diff orgchart.ml.expected orgchart.ml)))
+  (diff dune.inc dune.inc.gen)))
 
 (rule
- (alias runtest)
+ (deps
+  (:gen-dune ./gen-dune/main.exe))
  (action
-  (diff orgchart.mli.expected orgchart.mli)))
-
-(test
- (name orgchart_ml)
- (modules orgchart orgchart_ml)
- (package ocaml-protoc)
- (libraries pbrt))
+  (with-stdout-to
+   dune.inc.gen
+   (run
+    %{gen-dune}
+    calculator
+    example01
+    example03
+    example04
+    example05
+    file_server
+    orgchart))))

src/examples/dune.inc

@@ -0,0 +1,71 @@
+; dune file generated by './gen-dune/main.exe' -- do not edit.
+
+(rule
+ (alias runtest)
+ (action
+  (diff calculator.ml.expected calculator.ml)))
+
+(rule
+ (alias runtest)
+ (action
+  (diff calculator.mli.expected calculator.mli)))
+
+(rule
+ (alias runtest)
+ (action
+  (diff example01.ml.expected example01.ml)))
+
+(rule
+ (alias runtest)
+ (action
+  (diff example01.mli.expected example01.mli)))
+
+(rule
+ (alias runtest)
+ (action
+  (diff example03.ml.expected example03.ml)))
+
+(rule
+ (alias runtest)
+ (action
+  (diff example03.mli.expected example03.mli)))
+
+(rule
+ (alias runtest)
+ (action
+  (diff example04.ml.expected example04.ml)))
+
+(rule
+ (alias runtest)
+ (action
+  (diff example04.mli.expected example04.mli)))
+
+(rule
+ (alias runtest)
+ (action
+  (diff example05.ml.expected example05.ml)))
+
+(rule
+ (alias runtest)
+ (action
+  (diff example05.mli.expected example05.mli)))
+
+(rule
+ (alias runtest)
+ (action
+  (diff file_server.ml.expected file_server.ml)))
+
+(rule
+ (alias runtest)
+ (action
+  (diff file_server.mli.expected file_server.mli)))
+
+(rule
+ (alias runtest)
+ (action
+  (diff orgchart.ml.expected orgchart.ml)))
+
+(rule
+ (alias runtest)
+ (action
+  (diff orgchart.mli.expected orgchart.mli)))

src/examples/gen-dune/dune

@@ -0,0 +1,2 @@
+(executable
+ (name main))

src/examples/gen-dune/main.ml

@@ -0,0 +1,20 @@
+(* This is a helper program used to generate dune rules that get included to the
+   parent directory's dune file, via [../dune.inc]. *)
+
+let () =
+  Printf.printf
+    "; dune file generated by './gen-dune/main.exe' -- do not edit.\n";
+  Sys.argv |> Array.to_list |> List.tl |> List.sort String.compare
+  |> List.iter (fun arg ->
+         List.iter
+           (fun ext ->
+             let file = arg ^ ext in
+             Printf.printf
+               {|
+(rule
+ (alias runtest)
+ (action
+  (diff %s.expected %s)))
+|}
+               file file)
+           [ ".ml"; ".mli" ])