From b3577fde8bb34be645e2fee00e138bce6c10eecd Mon Sep 17 00:00:00 2001
From: Shon Feder <shon.feder@gmail.com>
Date: Tue, 25 Nov 2025 22:23:18 -0500
Subject: [PATCH] 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>
---
 bin/dune_init.ml                              | 25 ++++++++++++++++---
 doc/changes/changed/12791.md                  |  1 +
 .../test-cases/dune-init/dune-init.t/run.t    | 14 +++++++++++
 3 files changed, 37 insertions(+), 3 deletions(-)
 create mode 100644 doc/changes/changed/12791.md

diff --git a/bin/dune_init.ml b/bin/dune_init.ml
index c74d6fec29d..b1d5be32ab7 100644
--- a/bin/dune_init.ml
+++ b/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
diff --git a/doc/changes/changed/12791.md b/doc/changes/changed/12791.md
new file mode 100644
index 00000000000..3fa852c7461
--- /dev/null
+++ b/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)
diff --git a/test/blackbox-tests/test-cases/dune-init/dune-init.t/run.t b/test/blackbox-tests/test-cases/dune-init/dune-init.t/run.t
index c48ffb61a3f..7e26281a076 100644
--- a/test/blackbox-tests/test-cases/dune-init/dune-init.t/run.t
+++ b/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