Add a raw_backtrace field to Test.Error

[davidanthoff]

If an exception is thrown inside a @test statement, the stacktrace for that is stored as a string in backtrace. But for tooling it would be very convenient to be able to access this stacktrace in a more structured format, so it would be great if the raw backtrace could be stored in the Error struct as well.

[vchuravy]

Do you want a raw backtrace (e.g instruction pointers), or a symbolized variant?
The challenge is that we serialize those errors across a process boundary sometimes.

[davidanthoff]

A Vector{Base.StackTraces.StackFrame} would presumably best, i.e. what one gets from stacktrace. That would presumably work well with serializing as well?

[vchuravy]

julia/base/stacktraces.jl

Lines 51 to 67 in 98cacef

	struct StackFrame # this type should be kept platform-agnostic so that profiles can be dumped on one machine and read on another
	"the name of the function containing the execution context"
	func::Symbol
	"the path to the file containing the execution context"
	file::Symbol
	"the line number in the file containing the execution context"
	line::Int
	"the CodeInstance or CodeInfo containing the execution context (if it could be found), \
	or nothing (for example, if the inlining was a result of macro expansion)."
	linfo::Union{Core.MethodInstance, Core.CodeInstance, Method, CodeInfo, Nothing}
	"true if the code is from C"
	from_c::Bool
	"true if the code is from an inlined frame"
	inlined::Bool
	"representation of the pointer to the execution context as returned by `backtrace`"
	pointer::UInt64 # Large enough to be read losslessly on 32- and 64-bit machines.
	end

Still some "interesting to serialize" data here like linfo or pointer

[davidanthoff]

So maybe the easiest would just be a new type in the Test package?