# @testset expands all macros \*before\* executing the generated code
**URL:** https://discourse.julialang.org/t/testset-expands-all-macros-before-executing-the-generated-code/102197
**Category:** General Usage
**Tags:** testing, macros, metaprogramming
**Created:** [July 28, 2023, 2:19pm UTC](https://discourse.julialang.org/t/testset-expands-all-macros-before-executing-the-generated-code/102197 "2023-07-28T14:19:21Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@iago-lito](https://discourse.julialang.org/u/iago-lito)
#### Post date: [July 28, 2023, 2:19pm UTC](https://discourse.julialang.org/t/testset-expands-all-macros-before-executing-the-generated-code/102197/1 "2023-07-28T14:19:21Z")
Hello community. I’ve just spent hours confusingly revolving around the following quirk.
Given this code in my package:
```julia
macro a()
println("expand a")
:(println("exec a"))
end
macro b()
println("expand b")
:(println("exec b"))
end
```
And this user code:
```julia
println("invoke a")
@a
println("invoke b")
@b
```
I expect the following behaviour (based on the current REPL behaviour):
```julia
invoke a
expand a
exec a
invoke b
expand b
exec b
```
However, this is what happens when I automate the test:
```julia
using Test
@testset "" begin
println("invoke a")
@a
println("invoke b")
@b
end
```
```julia
expand a # !
expand b # !
invoke a
exec a
invoke b
exec b
```
1. Is that expected behaviour?
2. Is that somehow configurable?
3. Can I rely on the REPL behaviour (_i.e._ macros being expanded _on invocation_) and just work around `@testset` for my tests, or should I not assume that Julia upholds any guarantee regarding macros expansion time?
---
### Author:  [@Sukera](https://discourse.julialang.org/u/Sukera)
#### Post date: [July 28, 2023, 2:34pm UTC](https://discourse.julialang.org/t/testset-expands-all-macros-before-executing-the-generated-code/102197/2 "2023-07-28T14:34:59Z")
> [@iago-lito](#):
>
> Is that expected behaviour?
Yes, macros are expanded before the expanded code is executed. They are expanded outside-in (you can check with `Base.@macroexpand1`, if I’m not mistaken).
> [@iago-lito](#):
>
> Is that somehow configurable?
No. Macros are an AST transform.
> [@iago-lito](#):
>
> Can I rely on the REPL behaviour (_i.e._ macros being expanded _on invocation_) and just work around `@testset` for my tests, or should I not assume that Julia upholds any guarantee regarding macros expansion time?
I’m not sure I follow - when a macro is expanded, the code inside the macro building the expression (even if not contributing to the returned expression) still has to run.
---
### Author:  [@Benny](https://discourse.julialang.org/u/Benny)
#### Post date: [July 28, 2023, 6:43pm UTC](https://discourse.julialang.org/t/testset-expands-all-macros-before-executing-the-generated-code/102197/3 "2023-07-28T18:43:36Z")
It’s not particular to `@testset`, it’s because a `begin` block is a compound expression. The REPL reads one complete expression, not line, at a time; the `begin` block is only considered complete at the `end`.
```julia
julia> begin
println("invoke a")
@a
println("invoke b")
@b
end
expand a
expand b
invoke a
exec a
invoke b
exec b
```
---
### Author:  [@iago-lito](https://discourse.julialang.org/u/iago-lito)
#### Post date: [July 31, 2023, 8:52am UTC](https://discourse.julialang.org/t/testset-expands-all-macros-before-executing-the-generated-code/102197/4 "2023-07-31T08:52:15Z")
Thank you for feedback @Sukera @Benny 🙂 IIUC what I’m observing is rather related to how julia parser / expansion works, and also happens without @testset with plain `begin/end` blocks.
I guess I just need to be careful not to rely on the exact nesting order between my macro expansions and actual generated code execution, because I cannot enforce that they won’t be invoked within macros or `begin/end` blocks downstream ^ ^"