test(melange): add test exercising #7104 (#7204)

* test(melange): add test exercising #7104

Signed-off-by: Antonio Nuno Monteiro <anmonteiro@gmail.com>

test/blackbox-tests/test-cases/melange/virtual_lib_compilation.t/dune

@@ -0,0 +1,11 @@
+(executable
+ (name ml)
+ (modules ml)
+ (libraries vlib impl_ml))
+
+(melange.emit
+ (target output)
+ (alias melange)
+ (entries mel)
+ (libraries vlib impl_melange)
+ (module_system commonjs))

test/blackbox-tests/test-cases/melange/virtual_lib_compilation.t/dune-project

@@ -0,0 +1,3 @@
+(lang dune 3.8)
+
+(using melange 0.1)

test/blackbox-tests/test-cases/melange/virtual_lib_compilation.t/impl_melange/dune

@@ -0,0 +1,4 @@
+(library
+ (name impl_melange)
+ (modes melange)
+ (implements vlib))

test/blackbox-tests/test-cases/melange/virtual_lib_compilation.t/impl_melange/virt.ml

@@ -0,0 +1 @@
+let t = "melange"

test/blackbox-tests/test-cases/melange/virtual_lib_compilation.t/impl_ml/dune

@@ -0,0 +1,3 @@
+(library
+ (name impl_ml)
+ (implements vlib))

test/blackbox-tests/test-cases/melange/virtual_lib_compilation.t/impl_ml/virt.ml

@@ -0,0 +1 @@
+let t = "ml"

test/blackbox-tests/test-cases/melange/virtual_lib_compilation.t/mel.ml

@@ -0,0 +1 @@
+print_endline Virt.t

test/blackbox-tests/test-cases/melange/virtual_lib_compilation.t/ml.ml

@@ -0,0 +1 @@
+let () = print_endline Vlib_impl.hello

test/blackbox-tests/test-cases/melange/virtual_lib_compilation.t/run.t

@@ -0,0 +1,37 @@
+Test virtual lib in an exe / melange environment
+
+The native build passes
+
+  $ dune exec ./ml.exe --display=short
+      ocamldep impl_ml/.impl_ml.objs/virt.impl.d
+      ocamldep vlib/.vlib.objs/shared.impl.d
+      ocamldep vlib/.vlib.objs/virt.intf.d
+      ocamldep vlib/.vlib.objs/vlib_impl.impl.d
+        ocamlc vlib/.vlib.objs/byte/virt.{cmi,cmti}
+        ocamlc vlib/.vlib.objs/byte/vlib_impl.{cmi,cmo,cmt}
+      ocamlopt vlib/.vlib.objs/native/vlib_impl.{cmx,o}
+        ocamlc vlib/.vlib.objs/byte/shared.{cmi,cmo,cmt}
+        ocamlc .ml.eobjs/byte/dune__exe__Ml.{cmi,cmti}
+      ocamlopt vlib/.vlib.objs/native/shared.{cmx,o}
+      ocamlopt impl_ml/.impl_ml.objs/native/virt.{cmx,o}
+      ocamlopt .ml.eobjs/native/dune__exe__Ml.{cmx,o}
+      ocamlopt impl_ml/impl_ml.{a,cmxa}
+      ocamlopt ml.exe
+  Hello from ml
+
+Melange can't produce a `.cmj` solely from a virtual module `.cmi`, because it
+needs to consult the `.cmj` files of dependencies to know where the require
+call should be emitted
+
+  $ dune build @melange --display=short
+      ocamldep impl_melange/.impl_melange.objs/virt.impl.d
+          melc vlib/.vlib.objs/melange/virt.{cmi,cmti}
+          melc vlib/.vlib.objs/melange/vlib_impl.{cmi,cmj,cmt} (exit 2)
+  File "vlib/vlib_impl.ml", line 1:
+  Error: Virt not found, it means either the module does not exist or it is a namespace
+  [1]
+
+  $ output=_build/default/output/mel.js
+  $ test -f "$output" && node "$output"
+  [1]
+

test/blackbox-tests/test-cases/melange/virtual_lib_compilation.t/vlib/dune

@@ -0,0 +1,5 @@
+(library
+ (name vlib)
+ (wrapped false)
+ (modes :standard melange)
+ (virtual_modules virt))

test/blackbox-tests/test-cases/melange/virtual_lib_compilation.t/vlib/shared.ml

@@ -0,0 +1 @@
+let t = Vlib_impl.hello

test/blackbox-tests/test-cases/melange/virtual_lib_compilation.t/vlib/virt.mli

@@ -0,0 +1 @@
+val t : string

test/blackbox-tests/test-cases/melange/virtual_lib_compilation.t/vlib/vlib_impl.ml

@@ -0,0 +1 @@
+let hello = "Hello from " ^ Virt.t