add reference tests based on examples in docs

[hexaeder]

as of now, one has to manually check the preview docs for a PR to see wether everything works

I think it would be good to automate this process (reference testing for all of the plots in the docs)

[hexaeder]

My current idea for this would be to transform the literate scripts in docs/examples to jl scripts during runtests. For that one could add save commands to the examples which are hidden away in the md export for the documentation. Running the scripts would produce some pngs which could be compared against assets using ReferenceTests.jl or similar.

Additionally, there could be a new literate notebook referencetests.jl where we could put random code snippets to create test files. Even if those examples are not curated nor explained, i think there is value in displaying and testing different features of the package for interested users to scroll through. Stuff like #65 (comment)

[filchristou]

Currently the test environment is the same as the project environment. I think a first step would be to separate that.
The way I normally do this is with:

cd  test
julia
julia> ]
(@v1.7) pkg> activate .
(test) pkg> dev ..
(test) pkg> add CairoMakie, GLMakie, ...

This way the tester will not need to manually construct the needed environment every time.

Attention
Doing dev .. in the test folder breaks the possibility of calling (GraphMakie) pkg> test from inside the packet. And one need to manually run julia --project test test/runtests.jl. The relevant issue is JuliaLang/Pkg.jl#1585.

[filchristou]

or is there maybe a reason to go against that ?

[hexaeder]

yeah both the nested envionment and the extras section in project have their pros and cons... currently i was using the latter with TestEnv.jl to activate the test environment