Fix inline_tests action when partition list is empty

doc/changes/8848.md

@@ -0,0 +1 @@
+- Fix inline_tests when the partition list is empty (#8848, @hhugo)

src/dune_rules/inline_tests.ml

@@ -347,15 +347,18 @@ include Sub_system.Register_end_point (struct
                List.map partitions_flags ~f:(fun p -> action mode (flags p))
                |> Action_builder.all
              and+ () = Action_builder.paths source_files in
-             let run_tests = Action.concurrent actions in
-             let diffs =
-               List.map source_files ~f:(fun fn ->
-                 Path.as_in_build_dir_exn fn
-                 |> Path.Build.extend_basename ~suffix:".corrected"
-                 |> Action.diff ~optional:true fn)
-               |> Action.concurrent
-             in
-             Action.Full.make ~sandbox @@ Action.progn [ run_tests; diffs ]))
+             match actions with
+             | [] -> Action.Full.empty
+             | _ :: _ ->
+               let run_tests = Action.concurrent actions in
+               let diffs =
+                 List.map source_files ~f:(fun fn ->
+                   Path.as_in_build_dir_exn fn
+                   |> Path.Build.extend_basename ~suffix:".corrected"
+                   |> Action.diff ~optional:true fn)
+                 |> Action.concurrent
+               in
+               Action.Full.make ~sandbox @@ Action.progn [ run_tests; diffs ]))
     ;;
 
     let gen_rules c ~(info : Info.t) ~backends =

test/blackbox-tests/test-cases/inline_tests/parallel.t/backend/fake_backend_runner.ml

@@ -30,14 +30,14 @@ let register ~libname ~partition name run =
 
 let run () =
   Arg.parse speclist anon_fun usage_msg;
+  if !libname = "" then failwith "Should specify libname";
   if !list_partitions then
     let partitions =
       List.fold_left
-        (fun acc t -> StringSet.add t.partition acc)
+        (fun acc t -> if !libname = t.libname then StringSet.add t.partition acc else acc)
         StringSet.empty !tests
     in
-    StringSet.iter print_endline partitions
-  else if !libname = "" then failwith "Should specify libname";
+    StringSet.iter print_endline partitions;
   List.iter
     (fun t ->
       if t.libname = !libname && t.partition = !partition then (

test/blackbox-tests/test-cases/inline_tests/parallel.t/run.t

@@ -27,3 +27,14 @@ See that we indeed have 3 partitions
   p1
   p2
   p3
+
+
+  $ dune build --display short @test3/runtest
+        ocamlc test3/.test_lib3.inline-tests/.test_lib3.inline-tests.eobjs/byte/dune__exe__Inline_test_runner_test_lib3.{cmi,cmo,cmt}
+      ocamlopt test3/.test_lib3.inline-tests/.test_lib3.inline-tests.eobjs/native/dune__exe__Inline_test_runner_test_lib3.{cmx,o}
+      ocamlopt test3/.test_lib3.inline-tests/inline_test_runner_test_lib3.exe
+  inline_test_runner_test_lib3 test3/.test_lib3.inline-tests/partitions-best
+
+See that we have no partition.
+
+  $ cat _build/default/test3/.test_lib3.inline-tests/partitions-best

test/blackbox-tests/test-cases/inline_tests/parallel.t/test2/test_lib2.ml

@@ -1,19 +1,23 @@
 let () =
-  Fake_backend_runner.register ~libname:"test_lib" ~partition:"p1" "first test"
+  Fake_backend_runner.register ~libname:"test_lib2" ~partition:"p1" "first test"
     (fun () -> assert true)
 
 let () =
-  Fake_backend_runner.register ~libname:"test_lib" ~partition:"p1" "second test"
+  Fake_backend_runner.register ~libname:"test_lib2" ~partition:"p1" "second test"
     (fun () -> ()    )
 
 let () =
-  Fake_backend_runner.register ~libname:"test_lib" ~partition:"p2" "first test"
+  Fake_backend_runner.register ~libname:"test_lib2" ~partition:"p2" "first test"
     (fun () -> ())
 
 let () =
-  Fake_backend_runner.register ~libname:"test_lib" ~partition:"p3" "first test"
+  Fake_backend_runner.register ~libname:"test_lib2" ~partition:"p3" "first test"
     (fun () -> failwith "This failure is expected")
 
 let () =
   Fake_backend_runner.register ~libname:"other_lib" ~partition:"p1"
     "second test" (fun () -> assert false)
+
+let () =
+  Fake_backend_runner.register ~libname:"other_lib" ~partition:"pn"
+    "second test" (fun () -> assert false)

test/blackbox-tests/test-cases/inline_tests/parallel.t/test3/dune

@@ -0,0 +1,4 @@
+(library
+ (name test_lib3)
+ (libraries fake_backend_runner)
+ (inline_tests (backend fake_backend_2)))

test/blackbox-tests/test-cases/inline_tests/parallel.t/test3/test_lib3.ml

@@ -0,0 +1,3 @@
+let () =
+  Fake_backend_runner.register ~libname:"other_lib" ~partition:"p1"
+    "second test" (fun () -> assert false)