Add test select validation tests

Signed-off-by: Rudi Grinberg <me@rgrinberg.com>

src/dune/lib_dep.ml

@@ -42,7 +42,7 @@ module Select = struct
                        "The prefix for files in this select branch must be %S"
                        prefix
                    ];
-               if not (String.is_suffix result_fn ~suffix) then
+               if not (String.is_suffix file ~suffix) then
                  User_error.raise ~loc:loc_file
                    [ Pp.textf
                        "The suffix for files in this select branch must be %S"

test/blackbox-tests/dune.inc

@@ -1566,6 +1566,14 @@
    test-cases/select
    (progn (run %{exe:cram.exe} -test run.t) (diff? run.t run.t.corrected)))))
 
+(rule
+ (alias select-2-0-rules)
+ (deps (package dune) (source_tree test-cases/select-2-0-rules))
+ (action
+  (chdir
+   test-cases/select-2-0-rules
+   (progn (run %{exe:cram.exe} -test run.t) (diff? run.t run.t.corrected)))))
+
 (rule
  (alias several-packages)
  (deps (package dune) (source_tree test-cases/several-packages))
@@ -2100,6 +2108,7 @@
   (alias scope-bug)
   (alias scope-ppx-bug)
   (alias select)
+  (alias select-2-0-rules)
   (alias several-packages)
   (alias shadow-bindings)
   (alias stale-artifact-removal)
@@ -2305,6 +2314,7 @@
   (alias sandboxing)
   (alias scope-bug)
   (alias select)
+  (alias select-2-0-rules)
   (alias several-packages)
   (alias shadow-bindings)
   (alias stale-artifact-removal)

test/blackbox-tests/test-cases/select-2-0-rules/run.t

@@ -0,0 +1,19 @@
+  $ echo "(lang dune 2.0)" > dune-project
+  $ cat > dune <<EOF
+  > (library (name foo) (libraries (select foo.ml from (!bar -> f.ml))))
+  > EOF
+  $ dune build
+  File "dune", line 1, characters 60-64:
+  1 | (library (name foo) (libraries (select foo.ml from (!bar -> f.ml))))
+                                                                  ^^^^
+  Error: The prefix for files in this select branch must be "foo."
+  [1]
+  $ cat > dune <<EOF
+  > (library (name foo) (libraries (select foo.ml from (!bar -> foo.mli))))
+  > EOF
+  $ dune build
+  File "dune", line 1, characters 60-67:
+  1 | (library (name foo) (libraries (select foo.ml from (!bar -> foo.mli))))
+                                                                  ^^^^^^^
+  Error: The suffix for files in this select branch must be ".ml"
+  [1]