Gaurav Arya

@devmotion this is ready for another review. One important point: it seems to be [controversial](https://github.com/JuliaIO/TranscodingStreams.jl/issues/100) to introduce a `Test` dependency into the main package. An alternative is to register a...

@devmotion bump since this is blocking the plan chainrules work (please also see my comment above about a potential `AbstractFFTsTestUtils`)

I think a subpackage is a better solution than including the files. I've made the move, but I'm currently working on updating the CI so that the `AbstractFFTsTestUtils` package is...

@devmotion I've made the subpackage, but I'm just not able to understand the error on Julia nightly. It's easily reproducible on 1.9 by trying to develop the `AbstractFFTsTestUtils` package from...

There's also a "Circular dependency detected" warning for seemingly no reason on Julia 1.8: `AbstractFFTsTestUtils` is only a test dependency.

I've implemented the develop-from-test-script solution here

@devmotion tests should be sorted now

@devmotion are you ok with merging this? It's an imperfect solution (e.g. we won't get TagBot for AbstractFFTsTestUtils), but given our use case (a test utilities package that is highly...

A weak dependency is for a very particular situation that I don't think is satisfied here. Indeed, one could in theory want to call `test_fft_backend` without loading `Test` explicitly. And...

@devmotion I've updated the PR to avoid any special tricks when it comes to `Pkg.develop` / inconsistent state. Instead, `AbstractFFTsTestUtils` is a completely separate package with its own tests, which...