Crate stub_macro 

stub!() can be assigned to a variable:

let username = stub!(String);

This allows you to specify just type of the variable and continue working on other code, then come back later and specify its value.

Examples

fn assign() {
    // you can assign stub!() to a variable
    let username = stub!(String);
    println!("Hello {username}")
}

fn return_position() -> String {
    // you can use stub!() like todo!() in return position
    stub!()
}

fn infer_type() {
    // you can let the compiler automatically infer the type
    let status = stub!();
    if status { println!("Success") }
}

fn explicit_type() {
    // you can specify the type explicitly
    let status: bool = stub!();
    if status { println!("Success") }
}

fn custom_message() {
    // you can add a custom message
    let status: bool = stub!("Send a request to GitHub");
    if status { println!("Success") }
}

fn impl_example() -> impl core::fmt::Display {
    // you can use stub!() in return position even with `impl Trait` return type
    // note: `impl Trait` must be written as `impl dyn Trait` due to `macro_rules!` limitation
    stub!(impl dyn core::fmt::Display)
}

fn iter_example() -> impl Iterator<Item = u32> {
    // use stub_iter!() when the return type is an iterator
    stub_iter!()
}

#[cfg(feature = "futures")]
fn stream_example() -> impl futures_core::stream::Stream<Item = u32> {
    // use stub_stream!() when the return type is a stream
    stub_stream!()
}

fn explicit_type_with_message_example() -> u32 {
    // you can add
    stub!(u32, "Assigned to: {}", "John")
}

fn explicit_type_example() -> u32 {
    stub!(u32)
}

fn implicit_type_with_message_example() -> u32 {
    stub!("Assigned to: {}", "John")
}

fn implicit_type_example() -> u32 {
    stub!()
}

Behavior

When a stub is invoked, it will panic like a todo!() macro. However, unlike a todo!() macro, it will not make the subsequent parts of your code unreachable.

If a custom message is provided, it will be included in the panic message.

Notes

• stub!() macro is intended for use during development and should be replaced with actual implementations before production use.
• When using impl Trait in return position, you must use impl dyn Trait in the macro invocation due to a limitation in macro_rules!
• stub!(impl dyn Trait) requires the alloc feature.
• stub_stream!() requires the futures feature.

Macros

stub

See the crate-level documentation for the overview of this macro

stub_iter

See the crate-level documentation for the overview of this macro