feat(runtest): dune runtest for (tests)

Signed-off-by: Ali Caglayan <alizter@gmail.com>

Author: Alizter

bin/build.ml

@@ -101,6 +101,7 @@ let poll_handling_rpc_build_requests ~(common : Common.t) ~config =
          | Runtest test_paths ->
            Runtest_common.make_request
              ~contexts:setup.contexts
+             ~scontexts:setup.scontexts
              ~to_cwd:root.to_cwd
              ~test_paths
        in

bin/import.ml

@@ -39,6 +39,8 @@ include struct
   module Library = Library
   module Melange = Melange
   module Executables = Executables
+  module Dune_load = Dune_load
+  module Dir_contents = Dir_contents
 end
 
 include struct

bin/runtest.ml

@@ -44,6 +44,7 @@ let runtest_term =
     Build.run_build_command ~common ~config ~request:(fun setup ->
       Runtest_common.make_request
         ~contexts:setup.contexts
+        ~scontexts:setup.scontexts
         ~to_cwd:(Common.root common).to_cwd
         ~test_paths)
   | Error lock_held_by ->

bin/runtest_common.ml

@@ -4,11 +4,17 @@ module Test_kind = struct
   type t =
     | Runtest of Path.t
     | Cram of Path.t * Source.Cram_test.t
+    | Test_executable of Path.t * string (* dir, executable name *)
 
   let alias ~contexts = function
     | Cram (dir, cram) ->
       let name = Dune_engine.Alias.Name.of_string (Source.Cram_test.name cram) in
       Alias.in_dir ~name ~recursive:false ~contexts dir
+    | Test_executable (dir, exe_name) ->
+      (* CR-someday Alizter: get the proper alias, also check js_of_ocaml
+         runtst aliases? *)
+      let name = Dune_engine.Alias.Name.of_string ("runtest-" ^ exe_name) in
+      Alias.in_dir ~name ~recursive:false ~contexts dir
     | Runtest dir ->
       Alias.in_dir ~name:Dune_rules.Alias.runtest ~recursive:true ~contexts dir
   ;;
@@ -34,13 +40,53 @@ let find_cram_test cram_tests path =
     | Error (Dune_rules.Cram_rules.Missing_run_t _) | Ok _ -> None)
 ;;
 
-let all_tests_of_dir parent_dir =
+let find_test_executable ~sctx ~dir ~ml_file =
+  let open Memo.O in
+  let module_name = Filename.remove_extension ml_file in
+  match Dune_lang.Module_name.of_string_opt module_name with
+  | None -> Memo.return (Error `Not_a_test)
+  | Some module_name ->
+    let* dir_contents =
+      let dir =
+        Path.Build.append_source (Super_context.context sctx |> Context.build_dir) dir
+      in
+      Dir_contents.get sctx ~dir
+    in
+    let* ml_sources = Dir_contents.ocaml dir_contents
+    and* scope = Dir_contents.dir dir_contents |> Dune_rules.Scope.DB.find_by_dir in
+    Dune_rules.Ml_sources.find_origin
+      ml_sources
+      ~libs:(Dune_rules.Scope.libs scope)
+      [ module_name ]
+    >>| (function
+     | Some (Library _ | Executables _ | Melange _) | None -> Error `Not_a_test
+     | Some (Tests ({ exes; _ } as _test)) ->
+       let exe_names = Nonempty_list.to_list exes.names |> List.map ~f:snd in
+       if List.mem exe_names (Filename.remove_extension ml_file) ~equal:String.equal
+       then Ok (Filename.remove_extension ml_file)
+       else (
+         match exe_names with
+         | [ single_exe ] -> Ok single_exe
+         | [] | _ :: _ -> Error `Not_an_entry_point))
+;;
+
+let all_tests_of_dir ~sctx parent_dir =
   let open Memo.O in
   let+ cram_candidates =
     cram_tests_of_dir parent_dir
     >>| List.filter_map ~f:(fun res ->
       Result.to_option res
       |> Option.map ~f:(fun test -> Source.Cram_test.path test |> Path.Source.to_string))
+  and+ test_executable_candidates =
+    Source_tree.find_dir parent_dir
+    >>= function
+    | None -> Memo.return []
+    | Some source_dir ->
+      Source_tree.Dir.filenames source_dir
+      |> Filename.Set.to_list
+      |> List.filter ~f:(fun f -> String.is_suffix f ~suffix:".ml")
+      |> Memo.List.filter ~f:(fun ml_file ->
+        find_test_executable ~sctx ~dir:parent_dir ~ml_file >>| Result.is_ok)
   and+ dir_candidates =
     let* parent_source_dir = Source_tree.find_dir parent_dir in
     match parent_source_dir with
@@ -53,23 +99,23 @@ let all_tests_of_dir parent_dir =
         >>| Source_tree.Dir.path
         >>| Path.Source.to_string)
   in
-  List.concat [ cram_candidates; dir_candidates ]
+  List.concat [ cram_candidates; test_executable_candidates; dir_candidates ]
   |> String.Set.of_list
   |> String.Set.to_list
 ;;
 
-let explain_unsuccessful_search path ~parent_dir =
+let explain_unsuccessful_search ~sctx path ~parent_dir =
   let open Memo.O in
-  let+ candidates = all_tests_of_dir parent_dir in
+  let+ candidates = all_tests_of_dir ~sctx parent_dir in
   User_error.raise
     ~hints:(User_message.did_you_mean (Path.Source.to_string path) ~candidates)
     [ Pp.textf "%S does not match any known test." (Path.Source.to_string path) ]
 ;;
 
-(* [disambiguate_test_name path] is a function that takes in a
-   directory [path] and classifies it as either a cram test or a directory to
+(* [disambiguate_test_name path] is a function that takes in a directory [path]
+   and classifies it as either a cram test, test executable, or a directory to
    run tests in. *)
-let disambiguate_test_name path =
+let disambiguate_test_name ~sctx path =
   match Path.Source.parent path with
   | None -> Memo.return @@ Test_kind.Runtest (Path.source Path.Source.root)
   | Some parent_dir ->
@@ -80,27 +126,51 @@ let disambiguate_test_name path =
        (* If we find the cram test, then we request that is run. *)
        Memo.return (Test_kind.Cram (Path.source parent_dir, test))
      | None ->
-       (* If we don't find it, then we assume the user intended a directory for
-          @runtest to be used. *)
-       Source_tree.find_dir path
-       >>= (function
-        (* We need to make sure that this directory or file exists. *)
-        | Some _ -> Memo.return (Test_kind.Runtest (Path.source path))
-        | None -> explain_unsuccessful_search path ~parent_dir))
+       (* Check for test executables *)
+       let filename = Path.Source.basename path in
+       let* test_exe_opt =
+         find_test_executable ~sctx ~dir:parent_dir ~ml_file:filename
+         >>| function
+         | Ok exe_name -> Some exe_name
+         | Error `Not_an_entry_point ->
+           User_error.raise
+             [ Pp.textf
+                 "%S is used by multiple test executables and cannot be run directly."
+                 filename
+             ]
+         | Error `Not_a_test -> None
+       in
+       (match test_exe_opt with
+        | Some exe_name ->
+          (* Found a test executable for this ML file *)
+          Memo.return (Test_kind.Test_executable (Path.source parent_dir, exe_name))
+        | None ->
+          (* If we don't find it, then we assume the user intended a directory for
+             @runtest to be used. *)
+          Source_tree.find_dir path
+          >>= (function
+           (* We need to make sure that this directory or file exists. *)
+           | Some _ -> Memo.return (Test_kind.Runtest (Path.source path))
+           | None -> explain_unsuccessful_search ~sctx path ~parent_dir)))
 ;;
 
-let make_request ~contexts ~to_cwd ~test_paths =
+let make_request ~contexts ~scontexts ~to_cwd ~test_paths =
   List.map test_paths ~f:(fun dir ->
     let dir = Path.of_string dir |> Path.Expert.try_localize_external in
-    let contexts, src_dir =
+    let sctx, contexts, src_dir =
       match (Util.check_path contexts dir : Util.checked) with
-      | In_build_dir (context, dir) -> [ context ], dir
+      | In_build_dir (context, dir) ->
+        ( Dune_engine.Context_name.Map.find_exn scontexts (Context.name context)
+        , [ context ]
+        , dir )
       | In_source_dir dir ->
         (* We need to adjust the path here to make up for the current working directory. *)
         let dir =
           Path.Source.L.relative Path.Source.root (to_cwd @ Path.Source.explode dir)
         in
-        contexts, dir
+        ( Dune_engine.Context_name.Map.find_exn scontexts Context_name.default
+        , contexts
+        , dir )
       | In_private_context _ | In_install_dir _ ->
         User_error.raise
           [ Pp.textf "This path is internal to dune: %s" (Path.to_string_maybe_quoted dir)
@@ -113,7 +183,7 @@ let make_request ~contexts ~to_cwd ~test_paths =
           ]
     in
     let open Action_builder.O in
-    Action_builder.of_memo (disambiguate_test_name src_dir)
+    Action_builder.of_memo (disambiguate_test_name ~sctx src_dir)
     >>| Test_kind.alias ~contexts
     >>= Alias.request)
   |> Action_builder.all_unit

bin/runtest_common.mli

@@ -2,6 +2,7 @@ open Import
 
 val make_request
   :  contexts:Context.t list
+  -> scontexts:Super_context.t Context_name.Map.t
   -> to_cwd:string list
   -> test_paths:string list
   -> unit Action_builder.t

doc/changes/added/12785.md

@@ -0,0 +1,3 @@
+- `dune runtest` can now run individual test executables from `(tests)` stanzas
+  by providing their source files as arguments. (#12785, partially addresses
+  #870, @Alizter)