testing - 如何测试 `if @generated` 的两边？

Question

考虑我可能有一些我想测试的生成函数，如下所示。正在关注recommendation of the manual我让它们可选地生成。

# This code is taken directly from Base. 
# https://github.com/JuliaLang/julia/blob/592748adb25301a45bd6edef3ac0a93eed069852/base/namedtuple.jl#L220-L231
# So importing some of the helpers
using Base: merge_names, merge_types, sym_in

function my_merge_fail1(a::NamedTuple{an}, b::NamedTuple{bn}) where {an, bn}
    if @generated
        names = merge_names(an, bn)
        types = merge_types(names, a, b)
        vals = Any[ :(getfield($(sym_in(n, bn) ? :b : :a), $(QuoteNode(n)))) for n in names ]
        :(error("typo1"); NamedTuple{$names,$types}(($(vals...),)) )
    else
        names = merge_names(an, bn)
        types = merge_types(names, typeof(a), typeof(b))
        NamedTuple{names,types}(map(n->getfield(sym_in(n, bn) ? b : a, n), names))
    end
end

function my_merge_fail2(a::NamedTuple{an}, b::NamedTuple{bn}) where {an, bn}
    if @generated
        names = merge_names(an, bn)
        types = merge_types(names, a, b)
        vals = Any[ :(getfield($(sym_in(n, bn) ? :b : :a), $(QuoteNode(n)))) for n in names ]
        :(NamedTuple{$names,$types}(($(vals...),)) )
    else
        error("typo2")
        names = merge_names(an, bn)
        types = merge_types(names, typeof(a), typeof(b))
        NamedTuple{names,types}(map(n->getfield(sym_in(n, bn) ? b : a, n), names))
    end
end

现在，事实证明我在每一个中都犯了一个“错字”。我错误地将 error(...) 包含在它们中。在 my_merge_fail1 中，我在 @generated 分支中犯了错误，并在非生成分支中的 my_merge_fail2 中。

我的测试似乎只在一个分支中捕获它:

julia> using Test

julia> @test my_merge_fail1((a=1,), (b=2,)) == (a=1, b=2)
Error During Test at REPL[12]:1
  Test threw exception
  Expression: my_merge_fail1((a = 1,), (b = 2,)) == (a = 1, b = 2)
  typo1
  Stacktrace:
   [1] error(::String) at ./error.jl:33
   [2] macro expansion at ./REPL[6]:2 [inlined]
   [3] my_merge_fail1(::NamedTuple{(:a,),Tuple{Int64}}, ::NamedTuple{(:b,),Tuple{Int64}}) at ./REPL[6]:2
   [4] top-level scope at REPL[12]:1
   [5] eval(::Module, ::Any) at ./boot.jl:331
   [6] eval_user_input(::Any, ::REPL.REPLBackend) at /usr/local/src/julia/julia-master/usr/share/julia/stdlib/v1.4/REPL/src/REPL.jl:86
   [7] macro expansion at /usr/local/src/julia/julia-master/usr/share/julia/stdlib/v1.4/REPL/src/REPL.jl:118 [inlined]
   [8] (::REPL.var"#26#27"{REPL.REPLBackend})() at ./task.jl:333

ERROR: There was an error during testing

julia> @test my_merge_fail2((a=1,), (b=2,)) == (a=1, b=2)
Test Passed

我怎样才能改进我的测试？

Answer 1

可以通过从方法中提取降低的代码来实现这一点，您可以在其中指定是获取此方法的生成版本还是非生成版本的代码。此方法使用 eval 和 Base.invokelatest，因此会产生一些开销，但对于测试来说应该没问题。

function _invoke(f, x...; generated)
    sig = Core.Typeof(x)
    ci = code_lowered(f, sig; generated)[1]
    Meta.partially_inline!(
        ci.code, [], Tuple{typeof(f),sig.parameters...}, Any[sig.parameters...],
        0, 0, :propagate,
    )
    g = @eval @generated function $(gensym(:g))($([gensym() for _ in x]...))
        return $(QuoteNode(ci))
    end
    Base.invokelatest(g, x...)
end

然后您可以选择调用生成的或非生成的方法版本，如下所示:

julia> f(x, y) = @generated() ? :x : y
f (generic function with 1 method)

julia> _invoke(f, 1, 2; generated=true)
1

julia> _invoke(f, 1, 2; generated=false)
2