salsa/tests/mutate_in_place.rs
Niko Matsakis daaa78056a switch to new database design
Under this design, *all* databases are a
`DatabaseImpl<U>`, where the `U` implements
`UserData` (you can use `()` if there is none).

Code would default to `&dyn salsa::Database` but
if you want to give access to the userdata, you
can define a custom database trait
`MyDatabase: salsa::Databse` so long as you

* annotate `MyDatabase` trait definition of
  impls of `MyDatabase` with `#[salsa::db]`
* implement `MyDatabase` for `DatabaseImpl<U>`
  where `U` is your userdata (this could be a
  blanket impl, if you don't know the precise
  userdata type).

The `tests/common/mod.rs` shows the pattern.
2024-07-28 12:47:50 +00:00

29 lines
773 B
Rust

//! Test that a setting a field on a `#[salsa::input]`
//! overwrites and returns the old value.
use salsa::Setter;
use test_log::test;
#[salsa::input]
struct MyInput {
field: String,
}
#[test]
fn execute() {
let mut db = salsa::DatabaseImpl::new();
let input = MyInput::new(&db, "Hello".to_string());
// Overwrite field with an empty String
// and store the old value in my_string
let mut my_string = input.set_field(&mut db).to(String::new());
my_string.push_str(" World!");
// Set the field back to out initial String,
// expecting to get the empty one back
assert_eq!(input.set_field(&mut db).to(my_string), "");
// Check if the stored String is the one we expected
assert_eq!(input.field(&db), "Hello World!");
}