Function is_utf8_string 

pub fn is_utf8_string<InnerMatcherT>(
    inner: InnerMatcherT,
) -> IsEncodedStringMatcher<InnerMatcherT>
where
    InnerMatcherT: for<'a> Matcher<&'a str>,

Matches a byte sequence which is a UTF-8 encoded string matched by inner.

The matcher reports no match if either the string is not UTF-8 encoded or if inner does not match on the decoded string.

The input may be a slice &[u8] or a Vec of bytes.

let bytes: &[u8] = "A string".as_bytes();
verify_that!(bytes, is_utf8_string(eq("A string")))?; // Passes
let bytes: Vec<u8> = "A string".as_bytes().to_vec();
verify_that!(bytes, is_utf8_string(eq("A string")))?; // Passes
verify_that!(bytes, is_utf8_string(eq("Another string")))?; // Fails (inner matcher does not match)
let bytes: Vec<u8> = vec![255, 64, 128, 32];
verify_that!(bytes, is_utf8_string(anything()))?; // Fails (not UTF-8 encoded)