test: add a test focusing on merlin's configuration various granulari…

…ty levels

files with custom extension before preprocessing are not handled

test/blackbox-tests/test-cases/merlin/granularity.t

@@ -0,0 +1,168 @@
+# A utility to query merlin configuration for a file:
+  $ cat >merlin_conf.sh <<EOF
+  > #!/bin/sh
+  > FILE=\$1
+  > printf "(4:File%d:%s)" \${#FILE} \$FILE | dune ocaml-merlin \
+  >   | sed -E "s/[[:digit:]]+:/\?:/g" | sed -E "s/\)(\(+)/\n\1/g"
+  > EOF
+
+  $ chmod a+x merlin_conf.sh
+
+# Project sources
+
+  $ cat >dune-project <<EOF
+  > (lang dune 3.11)
+  > (using melange 0.1)
+  > 
+  > (dialect
+  >  (name mlx)
+  >  (implementation
+  >   (extension mlx)
+  >   (preprocess (run cat %{input-file}))
+  >   (merlin_reader mlx)))
+  > EOF
+
+  $ cat >pp.sh <<EOF
+  > #!/bin/sh
+  > sed 's/%INT%/42/g' \$1
+  > EOF
+
+  $ chmod a+x pp.sh
+
+  $ cat >dune <<EOF
+  > (executable
+  >  (name test)
+  >  (flags :standard -no-strict-formats)
+  >  (preprocess
+  >   (per_module
+  >    ((action (run ./pp.sh %{input-file})) pped))))
+  > 
+  > (rule
+  >  (action  (copy cppomod.cppo.ml cppomod.ml)))
+  > 
+  > (rule
+  >  (action  (copy wrongext.cppo.cml wrongext.ml)))
+  > EOF
+
+  $ cat >test.ml <<EOF
+  > print_endline Pped.x_42;;
+  > print_endline Mel.x;;
+  > print_endline Cppomod.x;;
+  > print_endline Wrongext.x;;
+  > EOF
+
+Both Pped's ml and mli files will be preprocessed
+  $ cat >pped.mli <<EOF
+  > val x_%INT% : string
+  > EOF
+
+  $ cat >pped.ml <<EOF
+  > let x_42 = "%INT%"
+  > EOF
+
+Melange module signature
+  $ cat >mel.mli <<EOF
+  > val x : string
+  > EOF
+
+Melange module implementation in Melange syntax
+  $ cat >mel.mlx <<EOF
+  > let x = "43"
+  > EOF
+
+A pped file with unconventionnal filename
+  $ cat >cppomod.cppo.ml <<EOF
+  > let x = "44"
+  > EOF
+
+  $ cat >wrongext.cppo.cml <<EOF
+  > let x = "45"
+  > EOF
+
+  $ dune build @check
+  $ dune exec ./test.exe
+  42
+  43
+  44
+  45
+
+# We now query Merlin configuration for the various source files:
+
+Some configuration fields are common to all the modules of a same stanza. This
+is the case for the stdlib, build and sources directories, flags and suffixes.
+
+Some configuration can be specific to a module like preprocessing.
+
+Dialects are specified by extensions so are specific to a file. This means a
+different reader might be used for the signature and the implementation.
+
+Note that suffixes provided by dialect should always be told to Merlin for
+locate to work correctly. 
+
+## Preprocessing:
+
+Is it expected that the suffix for implementation and interface is the same ?
+  $ ./merlin_conf.sh pped.ml | tee pped.out
+  ((?:STDLIB?:/Users/ulysse/.opam/5.1.0+trunk/lib/ocaml
+  (?:EXCLUDE_QUERY_DIR
+  (?:B?:$TESTCASE_ROOT/_build/default/.test.eobjs/byte
+  (?:S?:$TESTCASE_ROOT
+  (?:FLG(?:-open?:Dune__exe)
+  (?:FLG(?:-pp?:$TESTCASE_ROOT/_build/default/pp.sh)
+  (?:FLG(?:-w?:@1..3@5..28@30..39@43@46..47@49..57@61..62@67@69-?:-strict-sequence?:-strict-formats?:-short-paths?:-keep-locs?:-no-strict-formats?:-g)
+  (?:SUFFIX?:.mlx .mlx))
+
+  $ ./merlin_conf.sh pped.mli | diff pped.out -
+
+## Melange:
+
+As expected, the reader is not communicated for the standard mli
+  $ ./merlin_conf.sh mel.mli | tee mel.out
+  ((?:STDLIB?:/Users/ulysse/.opam/5.1.0+trunk/lib/ocaml
+  (?:EXCLUDE_QUERY_DIR
+  (?:B?:$TESTCASE_ROOT/_build/default/.test.eobjs/byte
+  (?:S?:$TESTCASE_ROOT
+  (?:FLG(?:-open?:Dune__exe)
+  (?:FLG(?:-w?:@1..3@5..28@30..39@43@46..47@49..57@61..62@67@69-?:-strict-sequence?:-strict-formats?:-short-paths?:-keep-locs?:-no-strict-formats?:-g)
+  (?:SUFFIX?:.mlx .mlx))
+
+The reader is set for the mlx file
+  $ ./merlin_conf.sh mel.mlx | diff mel.out -
+  7c7,8
+  < (?:SUFFIX?:.mlx .mlx))
+  \ No newline at end of file
+  ---
+  > (?:SUFFIX?:.mlx .mlx
+  > (?:READER(?:mlx)))
+  \ No newline at end of file
+  [1]
+
+## Unconventionnal file names:
+
+Users might have preprocessing steps that start with a non-conventionnal
+filename like `mymodule.cppo.ml`. Dune makes the assumption that the module name
+is always the first segment of a filename delimited by dots.
+
+  $ ./merlin_conf.sh cppomod.cppo.ml | tee cppomod.out
+  ((?:STDLIB?:/Users/ulysse/.opam/5.1.0+trunk/lib/ocaml
+  (?:EXCLUDE_QUERY_DIR
+  (?:B?:$TESTCASE_ROOT/_build/default/.test.eobjs/byte
+  (?:S?:$TESTCASE_ROOT
+  (?:FLG(?:-open?:Dune__exe)
+  (?:FLG(?:-w?:@1..3@5..28@30..39@43@46..47@49..57@61..62@67@69-?:-strict-sequence?:-strict-formats?:-short-paths?:-keep-locs?:-no-strict-formats?:-g)
+  (?:SUFFIX?:.mlx .mlx))
+
+  $ ./merlin_conf.sh cppomod.ml | diff cppomod.out -
+
+Note that this means unreleated files might be given the same configuration:
+
+  $ ./merlin_conf.sh cppomod.tralala.ml | diff cppomod.out -
+
+TODO: this heuristic might not be needed, we could match the filename directly
+
+And with unconventionnal extension: 
+(note that without appropriate suffix configuration Merlin will never jump to
+such files) 
+We could expect dune to get the wrongext module configuration
+  $ ./merlin_conf.sh wrongext.cppo.cml | tee wrongext.out
+  ((?:ERROR?:No config found for file wrongext.cppo.cml. Try calling `dune build`.))