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/// Assert a std::io::Read read_to_string() value is less than an expression.
///
/// * If true, return Result `Ok(())`.
///
/// * Otherwise, return Result `Err` with a diagnostic message.
///
/// This macro provides the same statements as [`assert_`],
/// except this macro returns a Result, rather than doing a panic.
///
/// This macro is useful for runtime checks, such as checking parameters,
/// or santizing inputs, or handling different results in different ways.
///
/// # Related
///
/// * [`assert_read_to_string_lt_expr`]
/// * [`assert_read_to_string_lt_expr_as_result`]
/// * [`debug_assert_read_to_string_lt_expr`]
///
#[macro_export]
macro_rules! assert_read_to_string_lt_expr_as_result {
($a_reader:expr, $b_expr:expr $(,)?) => ({
let mut a_string = String::new();
let a_result = $a_reader.read_to_string(&mut a_string);
if let Err(a_err) = a_result {
Err(format!(
concat!(
"assertion failed: `assert_read_to_string_lt_expr!(left_reader, right_expr)`\n",
" left_reader label: `{}`,\n",
" left_reader debug: `{:?}`,\n",
" right_expr label: `{}`,\n",
" right_expr debug: `{:?}`,\n",
" left err: `{:?}`"
),
stringify!($a_reader), $a_reader,
stringify!($b_expr), $b_expr,
a_err
))
} else {
let _a_size = a_result.unwrap();
let b_string = String::from($b_expr);
if a_string < b_string {
Ok(())
} else {
Err(format!(
concat!(
"assertion failed: `assert_read_to_string_lt_expr!(left_reader, right_expr)`\n",
" left_reader label: `{}`,\n",
" left_reader debug: `{:?}`,\n",
" right_expr label: `{}`,\n",
" right_expr debug: `{:?}`,\n",
" left: `{:?}`,\n",
" right: `{:?}`",
),
stringify!($a_reader), $a_reader,
stringify!($b_expr), $b_expr,
a_string,
b_string
))
}
}
});
}
#[cfg(test)]
mod tests {
#[allow(unused_imports)]
use std::io::Read;
#[test]
fn test_assert_read_to_string_lt_expr_as_result_x_success() {
let mut reader = "alpha".as_bytes();
let value = String::from("bravo");
let x = assert_read_to_string_lt_expr_as_result!(reader, &value);
assert_eq!(x, Ok(()));
}
#[test]
fn test_assert_read_to_string_lt_expr_as_result_x_failure() {
let mut reader = "bravo".as_bytes();
let value = String::from("alpha");
let x = assert_read_to_string_lt_expr_as_result!(reader, &value);
assert!(x.is_err());
assert_eq!(
x.unwrap_err(),
concat!(
"assertion failed: `assert_read_to_string_lt_expr!(left_reader, right_expr)`\n",
" left_reader label: `reader`,\n",
" left_reader debug: `[]`,\n",
" right_expr label: `&value`,\n",
" right_expr debug: `\"alpha\"`,\n",
" left: `\"bravo\"`,\n",
" right: `\"alpha\"`"
)
);
}
}
/// Assert a std::io::Read read_to_string() value is less than an expression.
///
/// * If true, return `()`.
///
/// * Otherwise, call [`panic!`] with a message and the values of the
/// expressions with their debug representations.
///
/// # Examples
///
/// ```rust
/// # #[macro_use] extern crate assertables;
/// # use std::panic;
/// use std::io::Read;
///
/// # fn main() {
/// // Return Ok
/// let mut reader = "alpha".as_bytes();
/// let value = String::from("bravo");
/// assert_read_to_string_lt_expr!(reader, &value);
/// //-> ()
///
/// // Panic with error message
/// let result = panic::catch_unwind(|| {
/// let mut reader = "bravo".as_bytes();
/// let value = String::from("alpha");
/// assert_read_to_string_lt_expr!(reader, &value);
/// //-> panic!
/// });
/// assert!(result.is_err());
/// let actual = result.unwrap_err().downcast::<String>().unwrap().to_string();
/// let expect = concat!(
/// "assertion failed: `assert_read_to_string_lt_expr!(left_reader, right_expr)`\n",
/// " left_reader label: `reader`,\n",
/// " left_reader debug: `[]`,\n",
/// " right_expr label: `&value`,\n",
/// " right_expr debug: `\"alpha\"`,\n",
/// " left: `\"bravo\"`,\n",
/// " right: `\"alpha\"`"
/// );
/// assert_eq!(actual, expect);
/// # }
/// ```
///
/// # Related
///
/// * [`assert_read_to_string_lt_expr`]
/// * [`assert_read_to_string_lt_expr_as_result`]
/// * [`debug_assert_read_to_string_lt_expr`]
///
#[macro_export]
macro_rules! assert_read_to_string_lt_expr {
($a_reader:expr, $b_expr:expr $(,)?) => ({
match assert_read_to_string_lt_expr_as_result!($a_reader, $b_expr) {
Ok(()) => (),
Err(err) => panic!("{}", err),
}
});
($a_reader:expr, $b_expr:expr, $($message:tt)+) => ({
match assert_read_to_string_lt_expr_as_result!($a_reader, $b_expr) {
Ok(()) => (),
Err(_err) => panic!("{}", $($message)+),
}
});
}
/// Assert a std::io::Read read_to_string() value is less than an expression.
///
/// This macro provides the same statements as [`assert_read_to_string_lt_expr`],
/// except this macro's statements are only enabled in non-optimized
/// builds by default. An optimized build will not execute this macro's
/// statements unless `-C debug-assertions` is passed to the compiler.
///
/// This macro is useful for checks that are too expensive to be present
/// in a release build but may be helpful during development.
///
/// The result of expanding this macro is always type checked.
///
/// An unchecked assertion allows a program in an inconsistent state to
/// keep running, which might have unexpected consequences but does not
/// introduce unsafety as long as this only happens in safe code. The
/// performance cost of assertions, however, is not measurable in general.
/// Replacing `assert*!` with `debug_assert*!` is thus only encouraged
/// after thorough profiling, and more importantly, only in safe code!
///
/// This macro is intendend to work in a similar way to
/// [`std::debug_assert`](https://doc.rust-lang.org/std/macro.debug_assert.html).
///
/// # Related
///
/// * [`assert_read_to_string_lt_expr`]
/// * [`assert_read_to_string_lt_expr`]
/// * [`debug_assert_read_to_string_lt_expr`]
///
#[macro_export]
macro_rules! debug_assert_read_to_string_lt_expr {
($($arg:tt)*) => {
if $crate::cfg!(debug_assertions) {
$crate::assert_read_to_string_lt_expr!($($arg)*);
}
};
}