我如你所愿，只提供翻译，不多加内容： 如何在Rust中模拟宏属性？

huangapple
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英文:

How can I mock a Macro attribute in Rust

问题

如何在Rust中进行测试时模拟一个宏属性，是否有某个库可以简化这个过程？

例如，#[my_macro] 修改了一个结构体，应用了另一个宏 #[account()] 到其中的一个字段，这个宏不在我的库中存在，但存在于使用我的宏的程序中：

  1. // lib.rs
  2. extern crate proc_macro;
  3. use proc_macro::TokenStream;
  5. mod macros;
  7. #[proc_macro_attribute]
  8. pub fn my_macro(args: TokenStream, input: TokenStream) -> TokenStream {
  9.       proc_macro::TokenStream::from(quote!(
  10.           pub struct MyModifiedStruct{
  11.             #[account()]
  12.             pub field1: u8
  13.           }
  14.       ))
  15. }

现在，如何在不为我的库中的#[account()]依赖项而导致错误的情况下测试my_macro？

  1. // tests/my_test.rs
  3. #[test]
  4. fn test_my_macro() {
  5.     #[my_macro]
  6.     pub struct MyStruct{}
  8.     let my_struct = MyStruct{field1:1} 
  9.     assert_eq!(my_struct.field1, 1)
  10. }

在Python中，我通常会模拟#[account()]属性，但不确定如何在Rust中进行这样的操作。

英文:

How can I mock a macro attribute when testing in Rust, is there some library to facilitate this?

For instance #[my_macro] modifies a struct applying another macro #[account()] to one of his fields, this macro doesn't exist in my library but exists in the programs which are using my macro:

  1. // lib.rs
  2. extern crate proc_macro;
  3. use proc_macro::TokenStream;
  5. mod macros;
  7. #[proc_macro_attribute]
  8. pub fn my_macro(args: TokenStream, input: TokenStream) -> TokenStream {
  9.       proc_macro::TokenStream::from(quote!(
  10.           pub struct MyModifiedStruct{
  11.             #[account()]
  12.             pub field1: u8
  13.           }
  14.       ))
  15. }

Now how can I test my_macro without getting an error for not having the #[account()] dependency in my library?

  1. // tests/my_test.rs
  3. #[test]
  4. fn test_my_macro() {
  5.     #[my_macro]
  6.     pub struct MyStruct{}
  8.     let my_struct = MyStruct{field1:1} 
  9.     assert_eq!(my_struct.field1, 1)
  11. }

My normal approach in Python would be mocking the #[account()] attribute, but not sure how can that be done in Rust.

答案1

得分: 1

我通常在Python中的正常方法是模拟 #[account()] 属性，但不确定如何在Rust中实现。

你可以在与 #[my_macro] 定义相同的 proc-macro crate 中实现 #[account] 属性宏的模拟版本，并将其导入到你在使用 #[my_macro] 的范围内：

lib.rs:

  1. extern crate proc_macro;
  2. use proc_macro::TokenStream;
  4. mod macros;
  6. #[proc_macro_attribute]
  7. pub fn my_macro(args: TokenStream, input: TokenStream) -> TokenStream {
  8.       proc_macro::TokenStream::from(quote!(
  9.           pub struct MyModifiedStruct{
  10.             #[account()]
  11.             pub field1: u8
  12.           }
  13.       ))
  14. }
  16. #[proc_macro_attribute]
  17. pub fn account(_args: TokenStream, input: TokenStream) -> TokenStream {
  18.     input
  19. }

tests/my_test.rs:

  1. // tests/my_test.rs
  2. use your_crate::{my_macro, account};
  4. #[test]
  5. fn test_my_macro() {
  6.     #[my_macro]
  7.     pub struct MyStruct{}
  9.     let my_struct = MyStruct{field1:1} 
  10.     assert_eq!(my_struct.field1, 1)
  11. }
英文:

> My normal approach in Python would be mocking the #[account()] attribute, but not sure how can that be done in Rust.

You could implement a mock version of your #[account] attribute macro in the same proc-macro crate as #[my_macro] is defined and import it into the scope you are using #[my_macro] in:

lib.rs:

  1. extern crate proc_macro;
  2. use proc_macro::TokenStream;
  4. mod macros;
  6. #[proc_macro_attribute]
  7. pub fn my_macro(args: TokenStream, input: TokenStream) -> TokenStream {
  8.       proc_macro::TokenStream::from(quote!(
  9.           pub struct MyModifiedStruct{
  10.             #[account()]
  11.             pub field1: u8
  12.           }
  13.       ))
  14. }
  16. #[proc_macro_attribute]
  17. pub fn account(_args: TokenStream, input: TokenStream) -> TokenStream {
  18.     input
  19. }

tests/my_test.rs:

  1. // tests/my_test.rs
  2. use your_crate::{my_macro, account};
  4. #[test]
  5. fn test_my_macro() {
  6.     #[my_macro]
  7.     pub struct MyStruct{}
  9.     let my_struct = MyStruct{field1:1} 
  10.     assert_eq!(my_struct.field1, 1)
  12. }

huangapple
  • 本文由 发表于 2023年2月18日 12:27:12
  • 转载请务必保留本文链接：https://go.coder-hub.com/75491192.html
  • rust
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