test: switching to custom lock dir

Signed-off-by: Ali Caglayan <[email protected]>

Author: Alizter

test/blackbox-tests/test-cases/pkg/lockdir-switch.t

@@ -0,0 +1,72 @@
+This test checks what happens when you lock with default directory then change
+workspace to use a custom lock directory.
+
+  $ . ./helpers.sh
+  $ mkrepo
+  $ mkpkg foo
+  $ add_mock_repo_if_needed
+
+  $ cat > dune-project <<EOF
+  > (lang dune 3.21)
+  > (package
+  >  (name myproject)
+  >  (depends foo))
+  > EOF
+
+Lock with default directory name:
+
+  $ dune pkg lock
+  Solution for dune.lock
+  
+  Dependencies common to all supported platforms:
+  - foo.0.0.1
+
+Now change the workspace to use a custom lock directory:
+
+  $ cat > dune-workspace <<EOF
+  > (lang dune 3.21)
+  > (lock_dir
+  >  (path custom.lock)
+  >  (repositories mock))
+  > (repository
+  >  (name mock)
+  >  (url "file://$PWD/mock-opam-repository"))
+  > EOF
+
+  $ cat > dune <<EOF
+  > (executable
+  >  (public_name bar))
+  > EOF
+
+  $ cat > bar.ml <<EOF
+  > let () = print_endline "hello from bar" ;;
+  > EOF
+
+  $ dune exec -- bar
+  Error: No rule found for default/.lock/dune.lock (context _private)
+  -> required by lock directory environment for context "default"
+  -> required by base environment for context "default"
+  -> required by loading findlib for context "default"
+  -> required by creating installed environment for "default"
+  [1]
+
+Now try with a context stanza that references the custom lock directory with a
+context stanza:
+
+  $ cat > dune-workspace <<EOF
+  > (lang dune 3.21)
+  > (context
+  >  (default
+  >   (lock_dir custom.lock)))
+  > (lock_dir
+  >  (path custom.lock)
+  >  (repositories mock))
+  > (repository
+  >  (name mock)
+  >  (url "file://$PWD/mock-opam-repository"))
+  > EOF
+
+This is working as intended. The error is not relevant here.
+
+  $ dune exec -- bar 
+  hello from bar