Change the name of "inner" function generated by #[sqlx::test]

[ciffelia]

Summary

This patch addresses an issue with the #[sqlx::test] attribute macro that causes problems when used in conjunction with the insta snapshot testing library.

#[sqlx::test(migrator = "mymodule::migrator")]
async fn select_foo(pool: PgPool) {
    let res = my_function_to_test(pool);
    insta::assert_debug_snapshot!(res); // we expect insta to generate a snapshot file named `mymodule__tests__select_foo.snap`
} 

When using sqlx::test, the test code is wrapped inside an inner function, which can lead to snapshot files being generated with the name of the inner function (inner), causing filename conflicts when multiple functions exist within the same module.

// expanded code
#[test]
fn select_foo() {
    async fn inner(pool: PgPool) {
        let res = my_function_to_test(pool);
        insta::assert_debug_snapshot!(res); // insta generates a snapshot file named `mymodule__tests__inner.snap`
    }
    // ...
    let f: fn(_) -> _ = inner;
    ::sqlx::testing::TestFn::run_test(f, args)
} 

mitsuhiko/insta#434

This PR modifies the sqlx::test macro to ensure that insta uses the correct function name (select_foo in this case) when generating snapshot files, thereby avoiding filename conflicts and ensuring that snapshot tests work as expected.

Changes

Modified the sqlx::test macro to generate the inner function with the original function name (select_foo in this case) when generating the test function, ensuring that insta uses the correct function name when generating snapshot files.

// expanded code
#[test]
fn select_foo() {
    async fn select_foo(pool: PgPool) {
        let res = my_function_to_test(pool);
        insta::assert_debug_snapshot!(res); // insta generates a snapshot file named `mymodule__tests__select_foo.snap`
    }
    // ...
    let f: fn(_) -> _ = select_foo;
    ::sqlx::testing::TestFn::run_test(f, args)
} 

[abonander]

I'm honestly surprised this doesn't clash. I figured the compiler would forbid this.