Define a custom assertion failure error for cross-version compat

[mistydemeo]

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Fixes #2840.

Note that this partially reverts c45cca8 - it was unnecessary on Ruby 2.0, but turns out to be necessary for compatibility with the system Ruby 2.3 on OS X 10.13.

[MikeMcQuaid]

Note that this partially reverts c45cca8 - it was unnecessary on Ruby 2.0, but turns out to be necessary for compatibility with the system Ruby 2.3 on OS X 10.13.

I was happy to leave that code as-is until it broke brew tests under Bundler 1.15.1. Can you ensure that's not the case now?

My main issue with the previous code was the lack of documentation: it was unclear in what situation any of those ifs would occur. I'd like to see that addressed if we merge this.

I think the ideal situation, though, would be using the same module names regardless of the version. This should be possible for brew tests at least by ensuring it's using the same version of e.g. minitest everywhere. It may not be possible on Ruby 2.3 for formulae so this may be acceptable as a short-term workaround but before High Sierra is released I think I'd like to see us upgrade to a vendored Ruby 2.3.X (matching the High Sierra version). Differing Ruby versions was an absolute nightmare between 1.8 and 2.0 and now we've got a solution I'd love to see us lean into it.

[mistydemeo]

it was unclear in what situation any of those ifs would occur. I'd like to see that addressed if we merge this.

Will do!

before High Sierra is released I think I'd like to see us upgrade to a vendored Ruby 2.3.X (matching the High Sierra version).

The static build for Ruby 2.3 is currently broken: https://bugs.ruby-lang.org/issues/13413 I'm going to take a stab at it, but it's a bit arcane.

[ilovezfs]

The static build for Ruby 2.3 is currently broken: https://bugs.ruby-lang.org/issues/13413 I'm going to take a stab at it, but it's a bit arcane.

I wonder if upstream would be willing to add static builds to their CI so that this doesn't happen again, assuming it does get fixed at some point.

[MikeMcQuaid]

Thanks @mistydemeo!