Enable cram by default starting with 3.0

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

Author: rgrinberg

CHANGES.md

@@ -60,6 +60,8 @@ Unreleased
   merlin configuration of a directory (defaulting to the current directory) in
   the Merlin configuration syntax. (#4250, @voodoos)
 
+- Enable cram tests by default (#4262, @rgrinberg)
+
 2.8.2 (21/01/2021)
 ------------------
 

doc/test/run.t

@@ -12,3 +12,4 @@ is fine, but you then need to update the list of such exceptions below.
   ../formatting.rst:.. note:: This section applies only to projects with ``(lang dune 1.x)``.
   ../formatting.rst:In ``(lang dune 1.x)``, no formatting is done by default. This feature is
   ../formatting.rst:(lang dune 2.0)
+  ../tests.rst:   (lang dune 2.7)

doc/tests.rst

@@ -474,12 +474,12 @@ Cram Tests
 
 Cram tests are expectation tests written in a shell-like syntax. They are ideal
 for testing binaries. Cram tests are auto discovered from files or directories
-with a ``.t`` extension, so they must be enabled manually in the
-``dune-project`` file:
+with a ``.t`` extension. This is automatically enabled starting from 3.0, for
+older versions, this must be manually enabled in the ``dune-project`` file:
 
 .. code:: scheme
 
-   (lang dune 3.0)
+   (lang dune 2.7)
    (cram enable)
 
 

src/dune_engine/dune_project.ml

@@ -442,6 +442,8 @@ let strict_package_deps_default ~(lang : Lang.Instance.t) =
 
 let explicit_js_mode_default ~(lang : Lang.Instance.t) = lang.version >= (2, 0)
 
+let cram_default ~(lang : Lang.Instance.t) = lang.version >= (3, 0)
+
 let format_extension_key =
   Extension.register Format_config.syntax Format_config.dparse_args
     Format_config.to_dyn
@@ -480,6 +482,7 @@ let infer ~dir packages =
   in
   let explicit_js_mode = explicit_js_mode_default ~lang in
   let strict_package_deps = strict_package_deps_default ~lang in
+  let cram = cram_default ~lang in
   let root = dir in
   let file_key = File_key.make ~root ~name in
   { name
@@ -506,7 +509,7 @@ let infer ~dir packages =
   ; explicit_js_mode
   ; format_config = None
   ; strict_package_deps
-  ; cram = false
+  ; cram
   }
 
 module Toggle = struct
@@ -720,7 +723,7 @@ let parse ~dir ~lang ~opam_packages ~file ~dir_status =
         in
         let cram =
           match cram with
-          | None -> false
+          | None -> cram_default ~lang
           | Some t -> Toggle.enabled t
         in
         let root = dir in