Empty missing dependencies while a (test) package is missing

[xclerc]

If one tries to set up inline tests with a jbuild file akin to the one below
while the inline_test package is not installed, the following message is
output:

Error: Library "ppx_inline_test" not found.
Hint: try: jbuilder external-lib-deps --missing @runtest

However, the execution of the suggested command line prints nothing.

---

(library
 ((name lib)
  (inline_tests)
  (preprocess (pps (ppx_inline_test)))))

[trefis]

I'm a bit surprised that this issue popped up again (cf #485 ).
Is there no way to add a regression test for this?

[ghost]

There is a test but it's only testing the libraries field, there might be another issue for the preprocess field.

[ghost]

I found the issue. It's a bit annoying to fix and the code that implement external-lib-deps already requires to be careful when writing the rules. I have an idea to catch external library dependencies more systematically without having to think about it while the rules, I'm going to try that.