Don't require test dependencies when building

[g2p]

Right now it seems like if a PPX test mentions a module, the dependency providing that module must be installed when building the tested code.
This should be made unnecessary, so that only building with runtest requires extra dependencies.

[ghost]

Currently the inline tests are always built and always end up in the final executable. Is that the issue here?

[g2p]

Pretty much. I have some tests that require some extra processing, and the extra dependencies are not acceptable for the library under test.
Since PPX rewriting is involved, could the tests be filtered out depending on build mode?

[ghost]

ppx_inline_test does have an option to drop the tests: -inline-test-drop. You would still depend on ppx_inline_test but not on the things needed by the tests

[g2p]

And I suppose this can be made conditional? Sorry for my jbuilder noobness.

[ghost]

Not currently. We added a notion of build profiles in the master of dune, so this could be use to do something different depending on which profile is selected. However there is still something missing in order to pass flag conditionally.

Since this is a common case, I'm wondering if we can't simply just drop tests when the profile is release, which is the case when compiling from opam.

[g2p]

I think disabling the tests in release mode would be great.

[ghost]

Could you open a ticket on ocaml/dune?