Macro assert_contains

macro_rules! assert_contains {
    ($ACTUAL: expr, $EXPECTED: expr) => { ... };
}

A macro to assert that one string is contained within another with a nice error message if they are not.

Usage: assert_contains!(actual, expected)

Is a macro so test error messages are on the same line as the failure;

Both arguments must be convertable into Strings (Into<String>)