Handle nested modules

[rofinn]

Currently, using nested modules can result in an UndefVarError.

julia> using Mocking

julia> Mocking.enable(; force=true)
Warning: Using experimental code which modifies jl_options global struct

julia> module A

       module B

       abstract type AbstractFoo end

       struct Foo <: AbstractFoo
           x::String
       end

       end

       bar(f::B.AbstractFoo) = println("blah")

       end
A

julia> import A: bar

julia> patch = @patch bar(f::B.AbstractFoo) = println("blar")
Mocking.Patch(:(bar(f::A.B.AbstractFoo)), ##665, Set(Any[:(A.B)]))

julia> Mocking.apply(patch) do
           bar(B.Foo("Blar"))
       end
ERROR: UndefVarError: A not defined
Stacktrace:
 [1] Mocking.PatchEnv(::Mocking.Patch, ::Bool) at /Users/rory/.playground/share/mocking/packages/v0.6/Mocking/src/Mocking.jl:156
 [2] apply(::Function, ::Mocking.Patch) at /Users/rory/.playground/share/mocking/packages/v0.6/Mocking/src/Mocking.jl:184

This is because the patch is only importing the top level module while the method is using a fully specified type signature:

ulia> Mocking.convert(Expr, patch)
quote
    import A.B
    bar(f::A.B.AbstractFoo) = begin
            (##662)(f)
        end
end

The solution should be to just recursively import all the parent modules.

[ararslan]

For 0.7, this will need to be

if VERSION >= v"0.7.0-DEV.1877"
    import .ModA
    import .ModA: bar, ModB
else
    import ModA
    import ModA: bar, ModB
end

because of JuliaLang/julia#23579

[codecov]

Codecov Report

Merging #52 into master will decrease coverage by 1.38%.
The diff coverage is 88.88%.

@@            Coverage Diff             @@
##           master      #52      +/-   ##
==========================================
- Coverage   93.52%   92.14%   -1.39%     
==========================================
  Files           4        4              
  Lines         278      280       +2     
==========================================
- Hits          260      258       -2     
- Misses         18       22       +4

Impacted Files	Coverage Δ
src/Mocking.jl	86.66% <88.88%> (-1.97%)	⬇️
src/expr.jl	94.25% <0%> (-2.3%)	⬇️

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[omus]

Can we indent the submodule content for clarity?

[iamed2]

Or even just end # ModA comments

[omus]

Why the change?

[omus]

lol, you fixed this in a very different way than I thought you would. XD

[omus]

https://travis-ci.org/invenia/Mocking.jl/jobs/402418514#L509

[rofinn]

I guess we'll need to start special casing Main on 0.7 now?

[rofinn]

Yeah, I'm not sure how to make these tests work on 0.7 because:

1. Manually, removing references to :Main doesn't work (and is ugly)
2. Referencing relative modules doesn't seem to work inside the patch on 0.7
3. Defining the test module inside Mocking doesn't work because we need to run Mocking.enable before loading the test module.

Maybe I'll only run the test on 0.6 for now with a comment on why.

[ararslan]

Could you not use fullname to get the full path to a module rather than having to use a relative reference? Also import Main, while a strange thing to do, does work in 0.7, at least at the REPL.

[iamed2]

Also import Main, while a strange thing to do, does work in 0.7, at least at the REPL.

It works when you're in Main, like at the REPL. If you're in a package, it won't work, because each package has its own top level module (e.g., parentmodule(Compat) == Compat).

[omus]

I'm fine with having this tested only on 0.6 for now.