Tests are not re-runnable in same session

[ericphanson]

My usual workflow is something like:

using TestEnv
TestEnv.activate()
include("test/runtests.jl")
# Change code in tests/package using Revise
include("test/runtests.jl")

However for Legolas that breaks in a few places:

Legolas.jl/test/runtests.jl

Line 5 in b86444c

@test_throws SchemaVersionDeclarationError("no prior `@schema` declaration found in current module") @version(TestV1, begin x end)

This test depends on what has already been defined in Main, which seems like a bad practice unto itself. That can be fixed by wrapping it in a module.

Legolas.jl/test/runtests.jl

Lines 552 to 558 in b86444c

	_num_calls = Ref{Int}(0)
	@version FieldErrorV2 begin
	a::Integer = begin
	_num_calls[] += 1
	a isa Function ? a() : a
	end
	end

This definition when called a second time says that it is an invalid redefinition. I suppose this too could be wrapped in a module (which gets replaced when the tests are re-included, so there is no struct redefinition).