Clarify error message for missing bundle script during bundle installation

[pyrmont]

Note

This post has been edited from the original. Comments prior to this comment refer to the earlier version of this post.

This PR changes the error message produced during bundle installation if a bundle directory does not contain a bundle script (i.e. ./bundle.janet or ./bundle/init.janet).

To assist with testing, it also adds a new assert-error-value macro to test/helpers.janet.

Background

If a user attempts to install a bundle that does not contain a bundle script, the bundle/install function can fail with an error message that does not clearly explain that the error is that this file is missing.

The error will occur in get-bundle-module and look like this:

error: could not find module @syspath/bundle/example:
    <syspath>/bundle/example.jimage
    <syspath>/bundle/example.janet
    <syspath>/bundle/example/init.janet
    <syspath>/bundle/example.so
  in require-1 [boot.janet] (tail call) on line 3126, column 20            
  in defer [boot.janet] on line 4200, column 7                             
  in get-bundle-module [boot.janet] on line 4192, column 5
  in edefer [boot.janet] on line 4351, column 19
  in bundle/install [boot.janet] (tail call) on line 4339, column 5
  [...]

Implementation

This PR changes the error message in get-bundle-module to specifically refer to the absence of a bundle script. There are some related clean-ups of the bundle/install logic (notably, initfile is changed to bscript to avoid visual confusion with infofile).

To assist with testing, this PR also adds an assert-error-value macro to test/helpers.janet so that tests can check that the error they are expecting is raised as opposed to a different kind of error.

[sogaiu]

I might be misunderstanding, but the original code looks like it went to some trouble to allow the possibility of an optional info file.

I wonder if there is a use for that kind of arrangement.

Guesses anyone?

[sogaiu]

Perhaps a minor point but I find infofile-* and initfile-* to be pretty easy to confuse in the context of the code in question.

I wonder if it's worth doing one of:

• inserting a hyphen (e.g. infofile-* -> info-file-*)
• removing file (e.g. infofile-src1 -> info-src)
• truncating file to f (e.g. infofile-src1 -> infof-src1)

or some other helpful thing :)

[pyrmont]

After further review, I realised that it's almost certainly intentional that you can call bundle/install for a bundle that does not include an info file. I've reverted the changes that required this file to exist and instead changed the error message thrown in get-bundle-module to more helpfully explain the problem. I've rewritten the OP to reflect this new version.