Add library dependency in dune init proj tests

Improves the generated template for projects by including a dependency
on the project library in the test stanza.

Signed-off-by: Shon Feder <shon.feder@gmail.com>

Author: shonfeder

bin/dune_init.ml

@@ -492,7 +492,6 @@ module Component = struct
     ;;
 
     let test ({ context; common; options } : Options.Test.t Options.t) =
-      (* Marking the current absence of test-specific options *)
       let dir = context.dir in
       let test_dune =
         Stanza_cst.test common options
@@ -526,6 +525,16 @@ module Component = struct
       File.Dune { dir; content; name = "dune-project" }
     ;;
 
+    (* Convert a libname to a dune atom that can be used to declare a library as
+       a dependency  *)
+    let lib_name_to_atom lib : Dune_lang.Atom.t =
+      Lib_name.to_string lib
+      |> String.map ~f:(function
+        | '-' -> '_' (* in case the lib_name is public, containing a `-` *)
+        | c -> c)
+      |> Dune_lang.Atom.of_string
+    ;;
+
     let proj_exec dir ({ context; common; options } : Options.Project.t Options.t) =
       let lib_target =
         src
@@ -536,10 +545,15 @@ module Component = struct
       in
       let test_target =
         let test_name = "test_" ^ Dune_lang.Atom.to_string common.name in
+        let libraries =
+          match common.public with
+          | None -> []
+          | Some lib -> [ lib_name_to_atom lib ]
+        in
         test
           { context = { context with dir = Path.Source.relative dir "test" }
           ; options = ()
-          ; common = { common with name = Dune_lang.Atom.of_string test_name }
+          ; common = { common with name = Dune_lang.Atom.of_string test_name; libraries }
           }
       in
       let bin_target =
@@ -564,10 +578,15 @@ module Component = struct
       in
       let test_target =
         let test_name = "test_" ^ Dune_lang.Atom.to_string common.name in
+        let libraries =
+          match common.public with
+          | None -> []
+          | Some lib -> [ lib_name_to_atom lib ]
+        in
         test
           { context = { context with dir = Path.Source.relative dir "test" }
           ; options = ()
-          ; common = { common with name = Dune_lang.Atom.of_string test_name }
+          ; common = { common with name = Dune_lang.Atom.of_string test_name; libraries }
           }
       in
       lib_target @ test_target

doc/changes/changed/12791.md

@@ -0,0 +1 @@
+- The `test/dune` file generated by `dune init proj` now depends on the project library. (#12791, @shonfeder)

test/blackbox-tests/test-cases/dune-init/dune-init.t/run.t

@@ -363,6 +363,13 @@ In particular, the `dune-project` file has the expected content:
 
   ; See the complete stanza docs at https://dune.readthedocs.io/en/stable/reference/dune-project/index.html
 
+And the test has a dependency on the library
+
+  $ cat new_exec_proj/test/dune
+  (test
+   (name test_new_exec_proj)
+   (libraries new_exec_proj))
+
 We can build the project:
 
   $ dune build --root new_exec_proj
@@ -474,6 +481,13 @@ In particular, the `dune-project` file has the expected content:
 
   ; See the complete stanza docs at https://dune.readthedocs.io/en/stable/reference/dune-project/index.html
 
+And the test has a dependency on the library
+
+  $ cat new_lib_proj/test/dune
+  (test
+   (name test_new_lib_proj)
+   (libraries new_lib_proj))
+
 We can build and install the project:
 
   $ dune build --root new_lib_proj @install