Macro match_err::assert_error

macro_rules! assert_error {
    ($var:expr, $ty:ty, $variant:ident $( ( $inner:expr ) )? $(, $($arg:tt)+)? ) => { ... };
}

Asserts the error against an enum-like error type by hiding the usage of downcast_ref method The error is required to implement PartialEq

Examples

 use match_err::*;
 use anyhow::anyhow;

 #[derive(thiserror::Error, Debug, PartialEq)]
 enum Error {
    #[error("not found")]
    NotFound,
    #[error("custom: {0}")]
    Custom(String),
 }

 let err = anyhow!(Error::Custom(String::from("internal")));

 assert_error!(err, Error, Custom(String::from("internal")));