Macro verify_that 

macro_rules! verify_that {
    ($actual:expr, $($expected:tt)+) => { ... };
}

Checks whether the Matcher given by the second argument matches the first argument.

Evaluates to Result::Ok(()) if the matcher matches and Result::Err(TestAssertionFailure) if it does not. The caller must then decide how to handle the Err variant. It has a few options:

• Abort the current function with the ? operator. This requires that the function return a suitable Result.
• Log the test failure and continue by calling the method and_log_failure.

Of course, one can also use all other standard methods on Result.

Invoking this macro by itself does not cause a test failure to be recorded or output. The resulting Result must be handled as described above to cause the test to be recorded as a failure.

Example:

verify_that!(42, eq(42))?; // This will pass.
verify_that!(42, eq(123)).and_log_failure();
            // This will log a test failure and allow execution to continue.
let _ = verify_that!(42, eq(123)); // This will do nothing.
verify_that!(42, eq(123))?; // This will fail, returning immediately.
verify_that!(42, eq(0))?; // This will not run.

This macro has special support for matching against containers. Namely:

• verify_that!(actual, [m1, m2, ...]) is equivalent to verify_that!(actual, contains_exactly![m1, m2, ...].in_order())
• verify_that!(actual, {m1, m2, ...}) is equivalent to verify_that!(actual, contains_exactly![m1, m2, ...])