Auto merge of #63124 - Centril:rollup-onohtqt, r=Centril

[rust.git] / src / liballoc / tests / str.rs

use std::borrow::Cow;
use std::cmp::Ordering::{Equal, Greater, Less};
use std::str::from_utf8;

#[test]
fn test_le() {
    assert!("" <= "");
    assert!("" <= "foo");
    assert!("foo" <= "foo");
    assert_ne!("foo", "bar");
}

#[test]
fn test_find() {
    assert_eq!("hello".find('l'), Some(2));
    assert_eq!("hello".find(|c:char| c == 'o'), Some(4));
    assert!("hello".find('x').is_none());
    assert!("hello".find(|c:char| c == 'x').is_none());
    assert_eq!("ประเทศไทย中华Việt Nam".find('华'), Some(30));
    assert_eq!("ประเทศไทย中华Việt Nam".find(|c: char| c == '华'), Some(30));
}

#[test]
fn test_rfind() {
    assert_eq!("hello".rfind('l'), Some(3));
    assert_eq!("hello".rfind(|c:char| c == 'o'), Some(4));
    assert!("hello".rfind('x').is_none());
    assert!("hello".rfind(|c:char| c == 'x').is_none());
    assert_eq!("ประเทศไทย中华Việt Nam".rfind('华'), Some(30));
    assert_eq!("ประเทศไทย中华Việt Nam".rfind(|c: char| c == '华'), Some(30));
}

#[test]
fn test_collect() {
    let empty = "";
    let s: String = empty.chars().collect();
    assert_eq!(empty, s);
    let data = "ประเทศไทย中";
    let s: String = data.chars().collect();
    assert_eq!(data, s);
}

#[test]
fn test_into_bytes() {
    let data = String::from("asdf");
    let buf = data.into_bytes();
    assert_eq!(buf, b"asdf");
}

#[test]
fn test_find_str() {
    // byte positions
    assert_eq!("".find(""), Some(0));
    assert!("banana".find("apple pie").is_none());

    let data = "abcabc";
    assert_eq!(data[0..6].find("ab"), Some(0));
    assert_eq!(data[2..6].find("ab"), Some(3 - 2));
    assert!(data[2..4].find("ab").is_none());

    let string = "ประเทศไทย中华Việt Nam";
    let mut data = String::from(string);
    data.push_str(string);
    assert!(data.find("ไท华").is_none());
    assert_eq!(data[0..43].find(""), Some(0));
    assert_eq!(data[6..43].find(""), Some(6 - 6));

    assert_eq!(data[0..43].find("ประ"), Some( 0));
    assert_eq!(data[0..43].find("ทศไ"), Some(12));
    assert_eq!(data[0..43].find("ย中"), Some(24));
    assert_eq!(data[0..43].find("iệt"), Some(34));
    assert_eq!(data[0..43].find("Nam"), Some(40));

    assert_eq!(data[43..86].find("ประ"), Some(43 - 43));
    assert_eq!(data[43..86].find("ทศไ"), Some(55 - 43));
    assert_eq!(data[43..86].find("ย中"), Some(67 - 43));
    assert_eq!(data[43..86].find("iệt"), Some(77 - 43));
    assert_eq!(data[43..86].find("Nam"), Some(83 - 43));

    // find every substring -- assert that it finds it, or an earlier occurrence.
    let string = "Việt Namacbaabcaabaaba";
    for (i, ci) in string.char_indices() {
        let ip = i + ci.len_utf8();
        for j in string[ip..].char_indices()
                             .map(|(i, _)| i)
                             .chain(Some(string.len() - ip))
        {
            let pat = &string[i..ip + j];
            assert!(match string.find(pat) {
                None => false,
                Some(x) => x <= i,
            });
            assert!(match string.rfind(pat) {
                None => false,
                Some(x) => x >= i,
            });
        }
    }
}

fn s(x: &str) -> String { x.to_string() }

macro_rules! test_concat {
    ($expected: expr, $string: expr) => {
        {
            let s: String = $string.concat();
            assert_eq!($expected, s);
        }
    }
}

#[test]
fn test_concat_for_different_types() {
    test_concat!("ab", vec![s("a"), s("b")]);
    test_concat!("ab", vec!["a", "b"]);
}

#[test]
fn test_concat_for_different_lengths() {
    let empty: &[&str] = &[];
    test_concat!("", empty);
    test_concat!("a", ["a"]);
    test_concat!("ab", ["a", "b"]);
    test_concat!("abc", ["", "a", "bc"]);
}

macro_rules! test_join {
    ($expected: expr, $string: expr, $delim: expr) => {
        {
            let s = $string.join($delim);
            assert_eq!($expected, s);
        }
    }
}

#[test]
fn test_join_for_different_types() {
    test_join!("a-b", ["a", "b"], "-");
    let hyphen = "-".to_string();
    test_join!("a-b", [s("a"), s("b")], &*hyphen);
    test_join!("a-b", vec!["a", "b"], &*hyphen);
    test_join!("a-b", &*vec!["a", "b"], "-");
    test_join!("a-b", vec![s("a"), s("b")], "-");
}

#[test]
fn test_join_for_different_lengths() {
    let empty: &[&str] = &[];
    test_join!("", empty, "-");
    test_join!("a", ["a"], "-");
    test_join!("a-b", ["a", "b"], "-");
    test_join!("-a-bc", ["", "a", "bc"], "-");
}

// join has fast paths for small separators up to 4 bytes
// this tests the slow paths.
#[test]
fn test_join_for_different_lengths_with_long_separator() {
    assert_eq!("～～～～～".len(), 15);

    let empty: &[&str] = &[];
    test_join!("", empty, "～～～～～");
    test_join!("a", ["a"], "～～～～～");
    test_join!("a～～～～～b", ["a", "b"], "～～～～～");
    test_join!("～～～～～a～～～～～bc", ["", "a", "bc"], "～～～～～");
}

#[test]
#[cfg(not(miri))] // Miri is too slow
fn test_unsafe_slice() {
    assert_eq!("ab", unsafe {"abc".get_unchecked(0..2)});
    assert_eq!("bc", unsafe {"abc".get_unchecked(1..3)});
    assert_eq!("", unsafe {"abc".get_unchecked(1..1)});
    fn a_million_letter_a() -> String {
        let mut i = 0;
        let mut rs = String::new();
        while i < 100000 {
            rs.push_str("aaaaaaaaaa");
            i += 1;
        }
        rs
    }
    fn half_a_million_letter_a() -> String {
        let mut i = 0;
        let mut rs = String::new();
        while i < 100000 {
            rs.push_str("aaaaa");
            i += 1;
        }
        rs
    }
    let letters = a_million_letter_a();
    assert_eq!(half_a_million_letter_a(),
        unsafe { letters.get_unchecked(0..500000)});
}

#[test]
fn test_starts_with() {
    assert!("".starts_with(""));
    assert!("abc".starts_with(""));
    assert!("abc".starts_with("a"));
    assert!(!"a".starts_with("abc"));
    assert!(!"".starts_with("abc"));
    assert!(!"ödd".starts_with("-"));
    assert!("ödd".starts_with("öd"));
}

#[test]
fn test_ends_with() {
    assert!("".ends_with(""));
    assert!("abc".ends_with(""));
    assert!("abc".ends_with("c"));
    assert!(!"a".ends_with("abc"));
    assert!(!"".ends_with("abc"));
    assert!(!"ddö".ends_with("-"));
    assert!("ddö".ends_with("dö"));
}

#[test]
fn test_is_empty() {
    assert!("".is_empty());
    assert!(!"a".is_empty());
}

#[test]
fn test_replacen() {
    assert_eq!("".replacen('a', "b", 5), "");
    assert_eq!("acaaa".replacen("a", "b", 3), "bcbba");
    assert_eq!("aaaa".replacen("a", "b", 0), "aaaa");

    let test = "test";
    assert_eq!(" test test ".replacen(test, "toast", 3), " toast toast ");
    assert_eq!(" test test ".replacen(test, "toast", 0), " test test ");
    assert_eq!(" test test ".replacen(test, "", 5), "   ");

    assert_eq!("qwer123zxc789".replacen(char::is_numeric, "", 3), "qwerzxc789");
}

#[test]
fn test_replace() {
    let a = "a";
    assert_eq!("".replace(a, "b"), "");
    assert_eq!("a".replace(a, "b"), "b");
    assert_eq!("ab".replace(a, "b"), "bb");
    let test = "test";
    assert_eq!(" test test ".replace(test, "toast"), " toast toast ");
    assert_eq!(" test test ".replace(test, ""), "   ");
}

#[test]
fn test_replace_2a() {
    let data = "ประเทศไทย中华";
    let repl = "دولة الكويت";

    let a = "ประเ";
    let a2 = "دولة الكويتทศไทย中华";
    assert_eq!(data.replace(a, repl), a2);
}

#[test]
fn test_replace_2b() {
    let data = "ประเทศไทย中华";
    let repl = "دولة الكويت";

    let b = "ะเ";
    let b2 = "ปรدولة الكويتทศไทย中华";
    assert_eq!(data.replace(b, repl), b2);
}

#[test]
fn test_replace_2c() {
    let data = "ประเทศไทย中华";
    let repl = "دولة الكويت";

    let c = "中华";
    let c2 = "ประเทศไทยدولة الكويت";
    assert_eq!(data.replace(c, repl), c2);
}

#[test]
fn test_replace_2d() {
    let data = "ประเทศไทย中华";
    let repl = "دولة الكويت";

    let d = "ไท华";
    assert_eq!(data.replace(d, repl), data);
}

#[test]
fn test_replace_pattern() {
    let data = "abcdαβγδabcdαβγδ";
    assert_eq!(data.replace("dαβ", "😺😺😺"), "abc😺😺😺γδabc😺😺😺γδ");
    assert_eq!(data.replace('γ', "😺😺😺"), "abcdαβ😺😺😺δabcdαβ😺😺😺δ");
    assert_eq!(data.replace(&['a', 'γ'] as &[_], "😺😺😺"), "😺😺😺bcdαβ😺😺😺δ😺😺😺bcdαβ😺😺😺δ");
    assert_eq!(data.replace(|c| c == 'γ', "😺😺😺"), "abcdαβ😺😺😺δabcdαβ😺😺😺δ");
}

// The current implementation of SliceIndex fails to handle methods
// orthogonally from range types; therefore, it is worth testing
// all of the indexing operations on each input.
mod slice_index {
    // Test a slicing operation **that should succeed,**
    // testing it on all of the indexing methods.
    //
    // This is not suitable for testing failure on invalid inputs.
    macro_rules! assert_range_eq {
        ($s:expr, $range:expr, $expected:expr)
        => {
            let mut s: String = $s.to_owned();
            let mut expected: String = $expected.to_owned();
            {
                let s: &str = &s;
                let expected: &str = &expected;

                assert_eq!(&s[$range], expected, "(in assertion for: index)");
                assert_eq!(s.get($range), Some(expected), "(in assertion for: get)");
                unsafe {
                    assert_eq!(
                        s.get_unchecked($range), expected,
                        "(in assertion for: get_unchecked)",
                    );
                }
            }
            {
                let s: &mut str = &mut s;
                let expected: &mut str = &mut expected;

                assert_eq!(
                    &mut s[$range], expected,
                    "(in assertion for: index_mut)",
                );
                assert_eq!(
                    s.get_mut($range), Some(&mut expected[..]),
                    "(in assertion for: get_mut)",
                );
                unsafe {
                    assert_eq!(
                        s.get_unchecked_mut($range), expected,
                        "(in assertion for: get_unchecked_mut)",
                    );
                }
            }
        }
    }

    // Make sure the macro can actually detect bugs,
    // because if it can't, then what are we even doing here?
    //
    // (Be aware this only demonstrates the ability to detect bugs
    //  in the FIRST method that panics, as the macro is not designed
    //  to be used in `should_panic`)
    #[test]
    #[should_panic(expected = "out of bounds")]
    fn assert_range_eq_can_fail_by_panic() {
        assert_range_eq!("abc", 0..5, "abc");
    }

    // (Be aware this only demonstrates the ability to detect bugs
    //  in the FIRST method it calls, as the macro is not designed
    //  to be used in `should_panic`)
    #[test]
    #[should_panic(expected = "==")]
    fn assert_range_eq_can_fail_by_inequality() {
        assert_range_eq!("abc", 0..2, "abc");
    }

    // Generates test cases for bad index operations.
    //
    // This generates `should_panic` test cases for Index/IndexMut
    // and `None` test cases for get/get_mut.
    macro_rules! panic_cases {
        ($(
            in mod $case_name:ident {
                data: $data:expr;

                // optional:
                //
                // a similar input for which DATA[input] succeeds, and the corresponding
                // output str. This helps validate "critical points" where an input range
                // straddles the boundary between valid and invalid.
                // (such as the input `len..len`, which is just barely valid)
                $(
                    good: data[$good:expr] == $output:expr;
                )*

                bad: data[$bad:expr];
                message: $expect_msg:expr; // must be a literal
            }
        )*) => {$(
            mod $case_name {
                #[test]
                fn pass() {
                    let mut v: String = $data.into();

                    $( assert_range_eq!(v, $good, $output); )*

                    {
                        let v: &str = &v;
                        assert_eq!(v.get($bad), None, "(in None assertion for get)");
                    }

                    {
                        let v: &mut str = &mut v;
                        assert_eq!(v.get_mut($bad), None, "(in None assertion for get_mut)");
                    }
                }

                #[test]
                #[should_panic(expected = $expect_msg)]
                fn index_fail() {
                    let v: String = $data.into();
                    let v: &str = &v;
                    let _v = &v[$bad];
                }

                #[test]
                #[should_panic(expected = $expect_msg)]
                fn index_mut_fail() {
                    let mut v: String = $data.into();
                    let v: &mut str = &mut v;
                    let _v = &mut v[$bad];
                }
            }
        )*};
    }

    #[test]
    fn simple_ascii() {
        assert_range_eq!("abc", .., "abc");

        assert_range_eq!("abc", 0..2, "ab");
        assert_range_eq!("abc", 0..=1, "ab");
        assert_range_eq!("abc", ..2, "ab");
        assert_range_eq!("abc", ..=1, "ab");

        assert_range_eq!("abc", 1..3, "bc");
        assert_range_eq!("abc", 1..=2, "bc");
        assert_range_eq!("abc", 1..1, "");
        assert_range_eq!("abc", 1..=0, "");
    }

    #[test]
    fn simple_unicode() {
        // 日本
        assert_range_eq!("\u{65e5}\u{672c}", .., "\u{65e5}\u{672c}");

        assert_range_eq!("\u{65e5}\u{672c}", 0..3, "\u{65e5}");
        assert_range_eq!("\u{65e5}\u{672c}", 0..=2, "\u{65e5}");
        assert_range_eq!("\u{65e5}\u{672c}", ..3, "\u{65e5}");
        assert_range_eq!("\u{65e5}\u{672c}", ..=2, "\u{65e5}");

        assert_range_eq!("\u{65e5}\u{672c}", 3..6, "\u{672c}");
        assert_range_eq!("\u{65e5}\u{672c}", 3..=5, "\u{672c}");
        assert_range_eq!("\u{65e5}\u{672c}", 3.., "\u{672c}");

        let data = "ประเทศไทย中华";
        assert_range_eq!(data, 0..3, "ป");
        assert_range_eq!(data, 3..6, "ร");
        assert_range_eq!(data, 3..3, "");
        assert_range_eq!(data, 30..33, "华");

        /*0: 中
          3: 华
          6: V
          7: i
          8: ệ
         11: t
         12:
         13: N
         14: a
         15: m */
        let ss = "中华Việt Nam";
        assert_range_eq!(ss, 3..6, "华");
        assert_range_eq!(ss, 6..16, "Việt Nam");
        assert_range_eq!(ss, 6..=15, "Việt Nam");
        assert_range_eq!(ss, 6.., "Việt Nam");

        assert_range_eq!(ss, 0..3, "中");
        assert_range_eq!(ss, 3..7, "华V");
        assert_range_eq!(ss, 3..=6, "华V");
        assert_range_eq!(ss, 3..3, "");
        assert_range_eq!(ss, 3..=2, "");
    }

    #[test]
    #[cfg(not(target_arch = "asmjs"))] // hits an OOM
    #[cfg(not(miri))] // Miri is too slow
    fn simple_big() {
        fn a_million_letter_x() -> String {
            let mut i = 0;
            let mut rs = String::new();
            while i < 100000 {
                rs.push_str("华华华华华华华华华华");
                i += 1;
            }
            rs
        }
        fn half_a_million_letter_x() -> String {
            let mut i = 0;
            let mut rs = String::new();
            while i < 100000 {
                rs.push_str("华华华华华");
                i += 1;
            }
            rs
        }
        let letters = a_million_letter_x();
        assert_range_eq!(letters, 0..3 * 500000, half_a_million_letter_x());
    }

    #[test]
    #[should_panic]
    fn test_slice_fail() {
        &"中华Việt Nam"[0..2];
    }

    panic_cases! {
        in mod rangefrom_len {
            data: "abcdef";
            good: data[6..] == "";
            bad: data[7..];
            message: "out of bounds";
        }

        in mod rangeto_len {
            data: "abcdef";
            good: data[..6] == "abcdef";
            bad: data[..7];
            message: "out of bounds";
        }

        in mod rangetoinclusive_len {
            data: "abcdef";
            good: data[..=5] == "abcdef";
            bad: data[..=6];
            message: "out of bounds";
        }

        in mod range_len_len {
            data: "abcdef";
            good: data[6..6] == "";
            bad: data[7..7];
            message: "out of bounds";
        }

        in mod rangeinclusive_len_len {
            data: "abcdef";
            good: data[6..=5] == "";
            bad: data[7..=6];
            message: "out of bounds";
        }
    }

    panic_cases! {
        in mod range_neg_width {
            data: "abcdef";
            good: data[4..4] == "";
            bad: data[4..3];
            message: "begin <= end (4 <= 3)";
        }

        in mod rangeinclusive_neg_width {
            data: "abcdef";
            good: data[4..=3] == "";
            bad: data[4..=2];
            message: "begin <= end (4 <= 3)";
        }
    }

    mod overflow {
        panic_cases! {
            in mod rangeinclusive {
                data: "hello";
                // note: using 0 specifically ensures that the result of overflowing is 0..0,
                //       so that `get` doesn't simply return None for the wrong reason.
                bad: data[0..=usize::max_value()];
                message: "maximum usize";
            }

            in mod rangetoinclusive {
                data: "hello";
                bad: data[..=usize::max_value()];
                message: "maximum usize";
            }
        }
    }

    mod boundary {
        const DATA: &str = "abcαβγ";

        const BAD_START: usize = 4;
        const GOOD_START: usize = 3;
        const BAD_END: usize = 6;
        const GOOD_END: usize = 7;
        const BAD_END_INCL: usize = BAD_END - 1;
        const GOOD_END_INCL: usize = GOOD_END - 1;

        // it is especially important to test all of the different range types here
        // because some of the logic may be duplicated as part of micro-optimizations
        // to dodge unicode boundary checks on half-ranges.
        panic_cases! {
            in mod range_1 {
                data: super::DATA;
                bad: data[super::BAD_START..super::GOOD_END];
                message:
                    "byte index 4 is not a char boundary; it is inside 'α' (bytes 3..5) of";
            }

            in mod range_2 {
                data: super::DATA;
                bad: data[super::GOOD_START..super::BAD_END];
                message:
                    "byte index 6 is not a char boundary; it is inside 'β' (bytes 5..7) of";
            }

            in mod rangefrom {
                data: super::DATA;
                bad: data[super::BAD_START..];
                message:
                    "byte index 4 is not a char boundary; it is inside 'α' (bytes 3..5) of";
            }

            in mod rangeto {
                data: super::DATA;
                bad: data[..super::BAD_END];
                message:
                    "byte index 6 is not a char boundary; it is inside 'β' (bytes 5..7) of";
            }

            in mod rangeinclusive_1 {
                data: super::DATA;
                bad: data[super::BAD_START..=super::GOOD_END_INCL];
                message:
                    "byte index 4 is not a char boundary; it is inside 'α' (bytes 3..5) of";
            }

            in mod rangeinclusive_2 {
                data: super::DATA;
                bad: data[super::GOOD_START..=super::BAD_END_INCL];
                message:
                    "byte index 6 is not a char boundary; it is inside 'β' (bytes 5..7) of";
            }

            in mod rangetoinclusive {
                data: super::DATA;
                bad: data[..=super::BAD_END_INCL];
                message:
                    "byte index 6 is not a char boundary; it is inside 'β' (bytes 5..7) of";
            }
        }
    }

    const LOREM_PARAGRAPH: &str = "\
    Lorem ipsum dolor sit amet, consectetur adipiscing elit. Suspendisse quis lorem \
    sit amet dolor ultricies condimentum. Praesent iaculis purus elit, ac malesuada \
    quam malesuada in. Duis sed orci eros. Suspendisse sit amet magna mollis, mollis \
    nunc luctus, imperdiet mi. Integer fringilla non sem ut lacinia. Fusce varius \
    tortor a risus porttitor hendrerit. Morbi mauris dui, ultricies nec tempus vel, \
    gravida nec quam.";

    // check the panic includes the prefix of the sliced string
    #[test]
    #[should_panic(expected="byte index 1024 is out of bounds of `Lorem ipsum dolor sit amet")]
    fn test_slice_fail_truncated_1() {
        &LOREM_PARAGRAPH[..1024];
    }
    // check the truncation in the panic message
    #[test]
    #[should_panic(expected="luctus, im`[...]")]
    fn test_slice_fail_truncated_2() {
        &LOREM_PARAGRAPH[..1024];
    }
}

#[test]
fn test_str_slice_rangetoinclusive_ok() {
    let s = "abcαβγ";
    assert_eq!(&s[..=2], "abc");
    assert_eq!(&s[..=4], "abcα");
}

#[test]
#[should_panic]
fn test_str_slice_rangetoinclusive_notok() {
    let s = "abcαβγ";
    &s[..=3];
}

#[test]
fn test_str_slicemut_rangetoinclusive_ok() {
    let mut s = "abcαβγ".to_owned();
    let s: &mut str = &mut s;
    assert_eq!(&mut s[..=2], "abc");
    assert_eq!(&mut s[..=4], "abcα");
}

#[test]
#[should_panic]
fn test_str_slicemut_rangetoinclusive_notok() {
    let mut s = "abcαβγ".to_owned();
    let s: &mut str = &mut s;
    &mut s[..=3];
}

#[test]
fn test_is_char_boundary() {
    let s = "ศไทย中华Việt Nam β-release 🐱123";
    assert!(s.is_char_boundary(0));
    assert!(s.is_char_boundary(s.len()));
    assert!(!s.is_char_boundary(s.len() + 1));
    for (i, ch) in s.char_indices() {
        // ensure character locations are boundaries and continuation bytes are not
        assert!(s.is_char_boundary(i), "{} is a char boundary in {:?}", i, s);
        for j in 1..ch.len_utf8() {
            assert!(!s.is_char_boundary(i + j),
                    "{} should not be a char boundary in {:?}", i + j, s);
        }
    }
}

#[test]
fn test_trim_start_matches() {
    let v: &[char] = &[];
    assert_eq!(" *** foo *** ".trim_start_matches(v), " *** foo *** ");
    let chars: &[char] = &['*', ' '];
    assert_eq!(" *** foo *** ".trim_start_matches(chars), "foo *** ");
    assert_eq!(" ***  *** ".trim_start_matches(chars), "");
    assert_eq!("foo *** ".trim_start_matches(chars), "foo *** ");

    assert_eq!("11foo1bar11".trim_start_matches('1'), "foo1bar11");
    let chars: &[char] = &['1', '2'];
    assert_eq!("12foo1bar12".trim_start_matches(chars), "foo1bar12");
    assert_eq!("123foo1bar123".trim_start_matches(|c: char| c.is_numeric()), "foo1bar123");
}

#[test]
fn test_trim_end_matches() {
    let v: &[char] = &[];
    assert_eq!(" *** foo *** ".trim_end_matches(v), " *** foo *** ");
    let chars: &[char] = &['*', ' '];
    assert_eq!(" *** foo *** ".trim_end_matches(chars), " *** foo");
    assert_eq!(" ***  *** ".trim_end_matches(chars), "");
    assert_eq!(" *** foo".trim_end_matches(chars), " *** foo");

    assert_eq!("11foo1bar11".trim_end_matches('1'), "11foo1bar");
    let chars: &[char] = &['1', '2'];
    assert_eq!("12foo1bar12".trim_end_matches(chars), "12foo1bar");
    assert_eq!("123foo1bar123".trim_end_matches(|c: char| c.is_numeric()), "123foo1bar");
}

#[test]
fn test_trim_matches() {
    let v: &[char] = &[];
    assert_eq!(" *** foo *** ".trim_matches(v), " *** foo *** ");
    let chars: &[char] = &['*', ' '];
    assert_eq!(" *** foo *** ".trim_matches(chars), "foo");
    assert_eq!(" ***  *** ".trim_matches(chars), "");
    assert_eq!("foo".trim_matches(chars), "foo");

    assert_eq!("11foo1bar11".trim_matches('1'), "foo1bar");
    let chars: &[char] = &['1', '2'];
    assert_eq!("12foo1bar12".trim_matches(chars), "foo1bar");
    assert_eq!("123foo1bar123".trim_matches(|c: char| c.is_numeric()), "foo1bar");
}

#[test]
fn test_trim_start() {
    assert_eq!("".trim_start(), "");
    assert_eq!("a".trim_start(), "a");
    assert_eq!("    ".trim_start(), "");
    assert_eq!("     blah".trim_start(), "blah");
    assert_eq!("   \u{3000}  wut".trim_start(), "wut");
    assert_eq!("hey ".trim_start(), "hey ");
}

#[test]
fn test_trim_end() {
    assert_eq!("".trim_end(), "");
    assert_eq!("a".trim_end(), "a");
    assert_eq!("    ".trim_end(), "");
    assert_eq!("blah     ".trim_end(), "blah");
    assert_eq!("wut   \u{3000}  ".trim_end(), "wut");
    assert_eq!(" hey".trim_end(), " hey");
}

#[test]
fn test_trim() {
    assert_eq!("".trim(), "");
    assert_eq!("a".trim(), "a");
    assert_eq!("    ".trim(), "");
    assert_eq!("    blah     ".trim(), "blah");
    assert_eq!("\nwut   \u{3000}  ".trim(), "wut");
    assert_eq!(" hey dude ".trim(), "hey dude");
}

#[test]
fn test_is_whitespace() {
    assert!("".chars().all(|c| c.is_whitespace()));
    assert!(" ".chars().all(|c| c.is_whitespace()));
    assert!("\u{2009}".chars().all(|c| c.is_whitespace())); // Thin space
    assert!("  \n\t   ".chars().all(|c| c.is_whitespace()));
    assert!(!"   _   ".chars().all(|c| c.is_whitespace()));
}

#[test]
fn test_is_utf8() {
    // deny overlong encodings
    assert!(from_utf8(&[0xc0, 0x80]).is_err());
    assert!(from_utf8(&[0xc0, 0xae]).is_err());
    assert!(from_utf8(&[0xe0, 0x80, 0x80]).is_err());
    assert!(from_utf8(&[0xe0, 0x80, 0xaf]).is_err());
    assert!(from_utf8(&[0xe0, 0x81, 0x81]).is_err());
    assert!(from_utf8(&[0xf0, 0x82, 0x82, 0xac]).is_err());
    assert!(from_utf8(&[0xf4, 0x90, 0x80, 0x80]).is_err());

    // deny surrogates
    assert!(from_utf8(&[0xED, 0xA0, 0x80]).is_err());
    assert!(from_utf8(&[0xED, 0xBF, 0xBF]).is_err());

    assert!(from_utf8(&[0xC2, 0x80]).is_ok());
    assert!(from_utf8(&[0xDF, 0xBF]).is_ok());
    assert!(from_utf8(&[0xE0, 0xA0, 0x80]).is_ok());
    assert!(from_utf8(&[0xED, 0x9F, 0xBF]).is_ok());
    assert!(from_utf8(&[0xEE, 0x80, 0x80]).is_ok());
    assert!(from_utf8(&[0xEF, 0xBF, 0xBF]).is_ok());
    assert!(from_utf8(&[0xF0, 0x90, 0x80, 0x80]).is_ok());
    assert!(from_utf8(&[0xF4, 0x8F, 0xBF, 0xBF]).is_ok());
}

#[test]
fn from_utf8_mostly_ascii() {
    // deny invalid bytes embedded in long stretches of ascii
    for i in 32..64 {
        let mut data = [0; 128];
        data[i] = 0xC0;
        assert!(from_utf8(&data).is_err());
        data[i] = 0xC2;
        assert!(from_utf8(&data).is_err());
    }
}

#[test]
fn from_utf8_error() {
    macro_rules! test {
        ($input: expr, $expected_valid_up_to: expr, $expected_error_len: expr) => {
            let error = from_utf8($input).unwrap_err();
            assert_eq!(error.valid_up_to(), $expected_valid_up_to);
            assert_eq!(error.error_len(), $expected_error_len);
        }
    }
    test!(b"A\xC3\xA9 \xFF ", 4, Some(1));
    test!(b"A\xC3\xA9 \x80 ", 4, Some(1));
    test!(b"A\xC3\xA9 \xC1 ", 4, Some(1));
    test!(b"A\xC3\xA9 \xC1", 4, Some(1));
    test!(b"A\xC3\xA9 \xC2", 4, None);
    test!(b"A\xC3\xA9 \xC2 ", 4, Some(1));
    test!(b"A\xC3\xA9 \xC2\xC0", 4, Some(1));
    test!(b"A\xC3\xA9 \xE0", 4, None);
    test!(b"A\xC3\xA9 \xE0\x9F", 4, Some(1));
    test!(b"A\xC3\xA9 \xE0\xA0", 4, None);
    test!(b"A\xC3\xA9 \xE0\xA0\xC0", 4, Some(2));
    test!(b"A\xC3\xA9 \xE0\xA0 ", 4, Some(2));
    test!(b"A\xC3\xA9 \xED\xA0\x80 ", 4, Some(1));
    test!(b"A\xC3\xA9 \xF1", 4, None);
    test!(b"A\xC3\xA9 \xF1\x80", 4, None);
    test!(b"A\xC3\xA9 \xF1\x80\x80", 4, None);
    test!(b"A\xC3\xA9 \xF1 ", 4, Some(1));
    test!(b"A\xC3\xA9 \xF1\x80 ", 4, Some(2));
    test!(b"A\xC3\xA9 \xF1\x80\x80 ", 4, Some(3));
}

#[test]
fn test_as_bytes() {
    // no null
    let v = [
        224, 184, 168, 224, 185, 132, 224, 184, 151, 224, 184, 162, 228,
        184, 173, 229, 141, 142, 86, 105, 225, 187, 135, 116, 32, 78, 97,
        109
    ];
    let b: &[u8] = &[];
    assert_eq!("".as_bytes(), b);
    assert_eq!("abc".as_bytes(), b"abc");
    assert_eq!("ศไทย中华Việt Nam".as_bytes(), v);
}

#[test]
#[should_panic]
fn test_as_bytes_fail() {
    // Don't double free. (I'm not sure if this exercises the
    // original problem code path anymore.)
    let s = String::from("");
    let _bytes = s.as_bytes();
    panic!();
}

#[test]
fn test_as_ptr() {
    let buf = "hello".as_ptr();
    unsafe {
        assert_eq!(*buf.offset(0), b'h');
        assert_eq!(*buf.offset(1), b'e');
        assert_eq!(*buf.offset(2), b'l');
        assert_eq!(*buf.offset(3), b'l');
        assert_eq!(*buf.offset(4), b'o');
    }
}

#[test]
fn vec_str_conversions() {
    let s1: String = String::from("All mimsy were the borogoves");

    let v: Vec<u8> = s1.as_bytes().to_vec();
    let s2: String = String::from(from_utf8(&v).unwrap());
    let mut i = 0;
    let n1 = s1.len();
    let n2 = v.len();
    assert_eq!(n1, n2);
    while i < n1 {
        let a: u8 = s1.as_bytes()[i];
        let b: u8 = s2.as_bytes()[i];
        assert_eq!(a, b);
        i += 1;
    }
}

#[test]
fn test_contains() {
    assert!("abcde".contains("bcd"));
    assert!("abcde".contains("abcd"));
    assert!("abcde".contains("bcde"));
    assert!("abcde".contains(""));
    assert!("".contains(""));
    assert!(!"abcde".contains("def"));
    assert!(!"".contains("a"));

    let data = "ประเทศไทย中华Việt Nam";
    assert!(data.contains("ประเ"));
    assert!(data.contains("ะเ"));
    assert!(data.contains("中华"));
    assert!(!data.contains("ไท华"));
}

#[test]
fn test_contains_char() {
    assert!("abc".contains('b'));
    assert!("a".contains('a'));
    assert!(!"abc".contains('d'));
    assert!(!"".contains('a'));
}

#[test]
fn test_split_at() {
    let s = "ศไทย中华Việt Nam";
    for (index, _) in s.char_indices() {
        let (a, b) = s.split_at(index);
        assert_eq!(&s[..a.len()], a);
        assert_eq!(&s[a.len()..], b);
    }
    let (a, b) = s.split_at(s.len());
    assert_eq!(a, s);
    assert_eq!(b, "");
}

#[test]
fn test_split_at_mut() {
    let mut s = "Hello World".to_string();
    {
        let (a, b) = s.split_at_mut(5);
        a.make_ascii_uppercase();
        b.make_ascii_lowercase();
    }
    assert_eq!(s, "HELLO world");
}

#[test]
#[should_panic]
fn test_split_at_boundscheck() {
    let s = "ศไทย中华Việt Nam";
    s.split_at(1);
}

#[test]
fn test_escape_unicode() {
    assert_eq!("abc".escape_unicode().to_string(), "\\u{61}\\u{62}\\u{63}");
    assert_eq!("a c".escape_unicode().to_string(), "\\u{61}\\u{20}\\u{63}");
    assert_eq!("\r\n\t".escape_unicode().to_string(), "\\u{d}\\u{a}\\u{9}");
    assert_eq!("'\"\\".escape_unicode().to_string(), "\\u{27}\\u{22}\\u{5c}");
    assert_eq!("\x00\x01\u{fe}\u{ff}".escape_unicode().to_string(), "\\u{0}\\u{1}\\u{fe}\\u{ff}");
    assert_eq!("\u{100}\u{ffff}".escape_unicode().to_string(), "\\u{100}\\u{ffff}");
    assert_eq!("\u{10000}\u{10ffff}".escape_unicode().to_string(), "\\u{10000}\\u{10ffff}");
    assert_eq!("ab\u{fb00}".escape_unicode().to_string(), "\\u{61}\\u{62}\\u{fb00}");
    assert_eq!("\u{1d4ea}\r".escape_unicode().to_string(), "\\u{1d4ea}\\u{d}");
}

#[test]
fn test_escape_debug() {
    // Note that there are subtleties with the number of backslashes
    // on the left- and right-hand sides. In particular, Unicode code points
    // are usually escaped with two backslashes on the right-hand side, as
    // they are escaped. However, when the character is unescaped (e.g., for
    // printable characters), only a single backslash appears (as the character
    // itself appears in the debug string).
    assert_eq!("abc".escape_debug().to_string(), "abc");
    assert_eq!("a c".escape_debug().to_string(), "a c");
    assert_eq!("éèê".escape_debug().to_string(), "éèê");
    assert_eq!("\r\n\t".escape_debug().to_string(), "\\r\\n\\t");
    assert_eq!("'\"\\".escape_debug().to_string(), "\\'\\\"\\\\");
    assert_eq!("\u{7f}\u{ff}".escape_debug().to_string(), "\\u{7f}\u{ff}");
    assert_eq!("\u{100}\u{ffff}".escape_debug().to_string(), "\u{100}\\u{ffff}");
    assert_eq!("\u{10000}\u{10ffff}".escape_debug().to_string(), "\u{10000}\\u{10ffff}");
    assert_eq!("ab\u{200b}".escape_debug().to_string(), "ab\\u{200b}");
    assert_eq!("\u{10d4ea}\r".escape_debug().to_string(), "\\u{10d4ea}\\r");
    assert_eq!("\u{301}a\u{301}bé\u{e000}".escape_debug().to_string(),
               "\\u{301}a\u{301}bé\\u{e000}");
}

#[test]
fn test_escape_default() {
    assert_eq!("abc".escape_default().to_string(), "abc");
    assert_eq!("a c".escape_default().to_string(), "a c");
    assert_eq!("éèê".escape_default().to_string(), "\\u{e9}\\u{e8}\\u{ea}");
    assert_eq!("\r\n\t".escape_default().to_string(), "\\r\\n\\t");
    assert_eq!("'\"\\".escape_default().to_string(), "\\'\\\"\\\\");
    assert_eq!("\u{7f}\u{ff}".escape_default().to_string(), "\\u{7f}\\u{ff}");
    assert_eq!("\u{100}\u{ffff}".escape_default().to_string(), "\\u{100}\\u{ffff}");
    assert_eq!("\u{10000}\u{10ffff}".escape_default().to_string(), "\\u{10000}\\u{10ffff}");
    assert_eq!("ab\u{200b}".escape_default().to_string(), "ab\\u{200b}");
    assert_eq!("\u{10d4ea}\r".escape_default().to_string(), "\\u{10d4ea}\\r");
}

#[test]
fn test_total_ord() {
    assert_eq!("1234".cmp("123"), Greater);
    assert_eq!("123".cmp("1234"), Less);
    assert_eq!("1234".cmp("1234"), Equal);
    assert_eq!("12345555".cmp("123456"), Less);
    assert_eq!("22".cmp("1234"), Greater);
}

#[test]
fn test_iterator() {
    let s = "ศไทย中华Việt Nam";
    let v = ['ศ','ไ','ท','ย','中','华','V','i','ệ','t',' ','N','a','m'];

    let mut pos = 0;
    let it = s.chars();

    for c in it {
        assert_eq!(c, v[pos]);
        pos += 1;
    }
    assert_eq!(pos, v.len());
    assert_eq!(s.chars().count(), v.len());
}

#[test]
fn test_rev_iterator() {
    let s = "ศไทย中华Việt Nam";
    let v = ['m', 'a', 'N', ' ', 't', 'ệ','i','V','华','中','ย','ท','ไ','ศ'];

    let mut pos = 0;
    let it = s.chars().rev();

    for c in it {
        assert_eq!(c, v[pos]);
        pos += 1;
    }
    assert_eq!(pos, v.len());
}

#[test]
#[cfg(not(miri))] // Miri is too slow
fn test_chars_decoding() {
    let mut bytes = [0; 4];
    for c in (0..0x110000).filter_map(std::char::from_u32) {
        let s = c.encode_utf8(&mut bytes);
        if Some(c) != s.chars().next() {
            panic!("character {:x}={} does not decode correctly", c as u32, c);
        }
    }
}

#[test]
#[cfg(not(miri))] // Miri is too slow
fn test_chars_rev_decoding() {
    let mut bytes = [0; 4];
    for c in (0..0x110000).filter_map(std::char::from_u32) {
        let s = c.encode_utf8(&mut bytes);
        if Some(c) != s.chars().rev().next() {
            panic!("character {:x}={} does not decode correctly", c as u32, c);
        }
    }
}

#[test]
fn test_iterator_clone() {
    let s = "ศไทย中华Việt Nam";
    let mut it = s.chars();
    it.next();
    assert!(it.clone().zip(it).all(|(x,y)| x == y));
}

#[test]
fn test_iterator_last() {
    let s = "ศไทย中华Việt Nam";
    let mut it = s.chars();
    it.next();
    assert_eq!(it.last(), Some('m'));
}

#[test]
fn test_chars_debug() {
    let s = "ศไทย中华Việt Nam";
    let c = s.chars();
    assert_eq!(
        format!("{:?}", c),
        r#"Chars(['ศ', 'ไ', 'ท', 'ย', '中', '华', 'V', 'i', 'ệ', 't', ' ', 'N', 'a', 'm'])"#
    );
}

#[test]
fn test_bytesator() {
    let s = "ศไทย中华Việt Nam";
    let v = [
        224, 184, 168, 224, 185, 132, 224, 184, 151, 224, 184, 162, 228,
        184, 173, 229, 141, 142, 86, 105, 225, 187, 135, 116, 32, 78, 97,
        109
    ];
    let mut pos = 0;

    for b in s.bytes() {
        assert_eq!(b, v[pos]);
        pos += 1;
    }
}

#[test]
fn test_bytes_revator() {
    let s = "ศไทย中华Việt Nam";
    let v = [
        224, 184, 168, 224, 185, 132, 224, 184, 151, 224, 184, 162, 228,
        184, 173, 229, 141, 142, 86, 105, 225, 187, 135, 116, 32, 78, 97,
        109
    ];
    let mut pos = v.len();

    for b in s.bytes().rev() {
        pos -= 1;
        assert_eq!(b, v[pos]);
    }
}

#[test]
fn test_bytesator_nth() {
    let s = "ศไทย中华Việt Nam";
    let v = [
        224, 184, 168, 224, 185, 132, 224, 184, 151, 224, 184, 162, 228,
        184, 173, 229, 141, 142, 86, 105, 225, 187, 135, 116, 32, 78, 97,
        109
    ];

    let mut b = s.bytes();
    assert_eq!(b.nth(2).unwrap(), v[2]);
    assert_eq!(b.nth(10).unwrap(), v[10]);
    assert_eq!(b.nth(200), None);
}

#[test]
fn test_bytesator_count() {
    let s = "ศไทย中华Việt Nam";

    let b = s.bytes();
    assert_eq!(b.count(), 28)
}

#[test]
fn test_bytesator_last() {
    let s = "ศไทย中华Việt Nam";

    let b = s.bytes();
    assert_eq!(b.last().unwrap(), 109)
}

#[test]
fn test_char_indicesator() {
    let s = "ศไทย中华Việt Nam";
    let p = [0, 3, 6, 9, 12, 15, 18, 19, 20, 23, 24, 25, 26, 27];
    let v = ['ศ','ไ','ท','ย','中','华','V','i','ệ','t',' ','N','a','m'];

    let mut pos = 0;
    let it = s.char_indices();

    for c in it {
        assert_eq!(c, (p[pos], v[pos]));
        pos += 1;
    }
    assert_eq!(pos, v.len());
    assert_eq!(pos, p.len());
}

#[test]
fn test_char_indices_revator() {
    let s = "ศไทย中华Việt Nam";
    let p = [27, 26, 25, 24, 23, 20, 19, 18, 15, 12, 9, 6, 3, 0];
    let v = ['m', 'a', 'N', ' ', 't', 'ệ','i','V','华','中','ย','ท','ไ','ศ'];

    let mut pos = 0;
    let it = s.char_indices().rev();

    for c in it {
        assert_eq!(c, (p[pos], v[pos]));
        pos += 1;
    }
    assert_eq!(pos, v.len());
    assert_eq!(pos, p.len());
}

#[test]
fn test_char_indices_last() {
    let s = "ศไทย中华Việt Nam";
    let mut it = s.char_indices();
    it.next();
    assert_eq!(it.last(), Some((27, 'm')));
}

#[test]
fn test_splitn_char_iterator() {
    let data = "\nMäry häd ä little lämb\nLittle lämb\n";

    let split: Vec<&str> = data.splitn(4, ' ').collect();
    assert_eq!(split, ["\nMäry", "häd", "ä", "little lämb\nLittle lämb\n"]);

    let split: Vec<&str> = data.splitn(4, |c: char| c == ' ').collect();
    assert_eq!(split, ["\nMäry", "häd", "ä", "little lämb\nLittle lämb\n"]);

    // Unicode
    let split: Vec<&str> = data.splitn(4, 'ä').collect();
    assert_eq!(split, ["\nM", "ry h", "d ", " little lämb\nLittle lämb\n"]);

    let split: Vec<&str> = data.splitn(4, |c: char| c == 'ä').collect();
    assert_eq!(split, ["\nM", "ry h", "d ", " little lämb\nLittle lämb\n"]);
}

#[test]
fn test_split_char_iterator_no_trailing() {
    let data = "\nMäry häd ä little lämb\nLittle lämb\n";

    let split: Vec<&str> = data.split('\n').collect();
    assert_eq!(split, ["", "Märy häd ä little lämb", "Little lämb", ""]);

    let split: Vec<&str> = data.split_terminator('\n').collect();
    assert_eq!(split, ["", "Märy häd ä little lämb", "Little lämb"]);
}

#[test]
fn test_rsplit() {
    let data = "\nMäry häd ä little lämb\nLittle lämb\n";

    let split: Vec<&str> = data.rsplit(' ').collect();
    assert_eq!(split, ["lämb\n", "lämb\nLittle", "little", "ä", "häd", "\nMäry"]);

    let split: Vec<&str> = data.rsplit("lämb").collect();
    assert_eq!(split, ["\n", "\nLittle ", "\nMäry häd ä little "]);

    let split: Vec<&str> = data.rsplit(|c: char| c == 'ä').collect();
    assert_eq!(split, ["mb\n", "mb\nLittle l", " little l", "d ", "ry h", "\nM"]);
}

#[test]
fn test_rsplitn() {
    let data = "\nMäry häd ä little lämb\nLittle lämb\n";

    let split: Vec<&str> = data.rsplitn(2, ' ').collect();
    assert_eq!(split, ["lämb\n", "\nMäry häd ä little lämb\nLittle"]);

    let split: Vec<&str> = data.rsplitn(2, "lämb").collect();
    assert_eq!(split, ["\n", "\nMäry häd ä little lämb\nLittle "]);

    let split: Vec<&str> = data.rsplitn(2, |c: char| c == 'ä').collect();
    assert_eq!(split, ["mb\n", "\nMäry häd ä little lämb\nLittle l"]);
}

#[test]
fn test_split_whitespace() {
    let data = "\n \tMäry   häd\tä  little lämb\nLittle lämb\n";
    let words: Vec<&str> = data.split_whitespace().collect();
    assert_eq!(words, ["Märy", "häd", "ä", "little", "lämb", "Little", "lämb"])
}

#[test]
fn test_lines() {
    let data = "\nMäry häd ä little lämb\n\r\nLittle lämb\n";
    let lines: Vec<&str> = data.lines().collect();
    assert_eq!(lines, ["", "Märy häd ä little lämb", "", "Little lämb"]);

    let data = "\r\nMäry häd ä little lämb\n\nLittle lämb"; // no trailing \n
    let lines: Vec<&str> = data.lines().collect();
    assert_eq!(lines, ["", "Märy häd ä little lämb", "", "Little lämb"]);
}

#[test]
fn test_splitator() {
    fn t(s: &str, sep: &str, u: &[&str]) {
        let v: Vec<&str> = s.split(sep).collect();
        assert_eq!(v, u);
    }
    t("--1233345--", "12345", &["--1233345--"]);
    t("abc::hello::there", "::", &["abc", "hello", "there"]);
    t("::hello::there", "::", &["", "hello", "there"]);
    t("hello::there::", "::", &["hello", "there", ""]);
    t("::hello::there::", "::", &["", "hello", "there", ""]);
    t("ประเทศไทย中华Việt Nam", "中华", &["ประเทศไทย", "Việt Nam"]);
    t("zzXXXzzYYYzz", "zz", &["", "XXX", "YYY", ""]);
    t("zzXXXzYYYz", "XXX", &["zz", "zYYYz"]);
    t(".XXX.YYY.", ".", &["", "XXX", "YYY", ""]);
    t("", ".", &[""]);
    t("zz", "zz", &["",""]);
    t("ok", "z", &["ok"]);
    t("zzz", "zz", &["","z"]);
    t("zzzzz", "zz", &["","","z"]);
}

#[test]
fn test_str_default() {
    use std::default::Default;

    fn t<S: Default + AsRef<str>>() {
        let s: S = Default::default();
        assert_eq!(s.as_ref(), "");
    }

    t::<&str>();
    t::<String>();
    t::<&mut str>();
}

#[test]
fn test_str_container() {
    fn sum_len(v: &[&str]) -> usize {
        v.iter().map(|x| x.len()).sum()
    }

    let s = "01234";
    assert_eq!(5, sum_len(&["012", "", "34"]));
    assert_eq!(5, sum_len(&["01", "2", "34", ""]));
    assert_eq!(5, sum_len(&[s]));
}

#[test]
fn test_str_from_utf8() {
    let xs = b"hello";
    assert_eq!(from_utf8(xs), Ok("hello"));

    let xs = "ศไทย中华Việt Nam".as_bytes();
    assert_eq!(from_utf8(xs), Ok("ศไทย中华Việt Nam"));

    let xs = b"hello\xFF";
    assert!(from_utf8(xs).is_err());
}

#[test]
fn test_pattern_deref_forward() {
    let data = "aabcdaa";
    assert!(data.contains("bcd"));
    assert!(data.contains(&"bcd"));
    assert!(data.contains(&"bcd".to_string()));
}

#[test]
fn test_empty_match_indices() {
    let data = "aä中!";
    let vec: Vec<_> = data.match_indices("").collect();
    assert_eq!(vec, [(0, ""), (1, ""), (3, ""), (6, ""), (7, "")]);
}

#[test]
fn test_bool_from_str() {
    assert_eq!("true".parse().ok(), Some(true));
    assert_eq!("false".parse().ok(), Some(false));
    assert_eq!("not even a boolean".parse::<bool>().ok(), None);
}

#[cfg(not(miri))] // Miri is too slow
fn check_contains_all_substrings(s: &str) {
    assert!(s.contains(""));
    for i in 0..s.len() {
        for j in i+1..=s.len() {
            assert!(s.contains(&s[i..j]));
        }
    }
}

#[test]
#[cfg(not(miri))] // Miri is too slow
fn strslice_issue_16589() {
    assert!("bananas".contains("nana"));

    // prior to the fix for #16589, x.contains("abcdabcd") returned false
    // test all substrings for good measure
    check_contains_all_substrings("012345678901234567890123456789bcdabcdabcd");
}

#[test]
fn strslice_issue_16878() {
    assert!(!"1234567ah012345678901ah".contains("hah"));
    assert!(!"00abc01234567890123456789abc".contains("bcabc"));
}


#[test]
#[cfg(not(miri))] // Miri is too slow
fn test_strslice_contains() {
    let x = "There are moments, Jeeves, when one asks oneself, 'Do trousers matter?'";
    check_contains_all_substrings(x);
}

#[test]
fn test_rsplitn_char_iterator() {
    let data = "\nMäry häd ä little lämb\nLittle lämb\n";

    let mut split: Vec<&str> = data.rsplitn(4, ' ').collect();
    split.reverse();
    assert_eq!(split, ["\nMäry häd ä", "little", "lämb\nLittle", "lämb\n"]);

    let mut split: Vec<&str> = data.rsplitn(4, |c: char| c == ' ').collect();
    split.reverse();
    assert_eq!(split, ["\nMäry häd ä", "little", "lämb\nLittle", "lämb\n"]);

    // Unicode
    let mut split: Vec<&str> = data.rsplitn(4, 'ä').collect();
    split.reverse();
    assert_eq!(split, ["\nMäry häd ", " little l", "mb\nLittle l", "mb\n"]);

    let mut split: Vec<&str> = data.rsplitn(4, |c: char| c == 'ä').collect();
    split.reverse();
    assert_eq!(split, ["\nMäry häd ", " little l", "mb\nLittle l", "mb\n"]);
}

#[test]
fn test_split_char_iterator() {
    let data = "\nMäry häd ä little lämb\nLittle lämb\n";

    let split: Vec<&str> = data.split(' ').collect();
    assert_eq!( split, ["\nMäry", "häd", "ä", "little", "lämb\nLittle", "lämb\n"]);

    let mut rsplit: Vec<&str> = data.split(' ').rev().collect();
    rsplit.reverse();
    assert_eq!(rsplit, ["\nMäry", "häd", "ä", "little", "lämb\nLittle", "lämb\n"]);

    let split: Vec<&str> = data.split(|c: char| c == ' ').collect();
    assert_eq!( split, ["\nMäry", "häd", "ä", "little", "lämb\nLittle", "lämb\n"]);

    let mut rsplit: Vec<&str> = data.split(|c: char| c == ' ').rev().collect();
    rsplit.reverse();
    assert_eq!(rsplit, ["\nMäry", "häd", "ä", "little", "lämb\nLittle", "lämb\n"]);

    // Unicode
    let split: Vec<&str> = data.split('ä').collect();
    assert_eq!( split, ["\nM", "ry h", "d ", " little l", "mb\nLittle l", "mb\n"]);

    let mut rsplit: Vec<&str> = data.split('ä').rev().collect();
    rsplit.reverse();
    assert_eq!(rsplit, ["\nM", "ry h", "d ", " little l", "mb\nLittle l", "mb\n"]);

    let split: Vec<&str> = data.split(|c: char| c == 'ä').collect();
    assert_eq!( split, ["\nM", "ry h", "d ", " little l", "mb\nLittle l", "mb\n"]);

    let mut rsplit: Vec<&str> = data.split(|c: char| c == 'ä').rev().collect();
    rsplit.reverse();
    assert_eq!(rsplit, ["\nM", "ry h", "d ", " little l", "mb\nLittle l", "mb\n"]);
}

#[test]
fn test_rev_split_char_iterator_no_trailing() {
    let data = "\nMäry häd ä little lämb\nLittle lämb\n";

    let mut split: Vec<&str> = data.split('\n').rev().collect();
    split.reverse();
    assert_eq!(split, ["", "Märy häd ä little lämb", "Little lämb", ""]);

    let mut split: Vec<&str> = data.split_terminator('\n').rev().collect();
    split.reverse();
    assert_eq!(split, ["", "Märy häd ä little lämb", "Little lämb"]);
}

#[test]
fn test_utf16_code_units() {
    assert_eq!("é\u{1F4A9}".encode_utf16().collect::<Vec<u16>>(),
               [0xE9, 0xD83D, 0xDCA9])
}

#[test]
fn starts_with_in_unicode() {
    assert!(!"├── Cargo.toml".starts_with("# "));
}

#[test]
fn starts_short_long() {
    assert!(!"".starts_with("##"));
    assert!(!"##".starts_with("####"));
    assert!("####".starts_with("##"));
    assert!(!"##ä".starts_with("####"));
    assert!("####ä".starts_with("##"));
    assert!(!"##".starts_with("####ä"));
    assert!("##ä##".starts_with("##ä"));

    assert!("".starts_with(""));
    assert!("ä".starts_with(""));
    assert!("#ä".starts_with(""));
    assert!("##ä".starts_with(""));
    assert!("ä###".starts_with(""));
    assert!("#ä##".starts_with(""));
    assert!("##ä#".starts_with(""));
}

#[test]
fn contains_weird_cases() {
    assert!("* \t".contains(' '));
    assert!(!"* \t".contains('?'));
    assert!(!"* \t".contains('\u{1F4A9}'));
}

#[test]
fn trim_ws() {
    assert_eq!(" \t  a \t  ".trim_start_matches(|c: char| c.is_whitespace()),
                    "a \t  ");
    assert_eq!(" \t  a \t  ".trim_end_matches(|c: char| c.is_whitespace()),
               " \t  a");
    assert_eq!(" \t  a \t  ".trim_start_matches(|c: char| c.is_whitespace()),
                    "a \t  ");
    assert_eq!(" \t  a \t  ".trim_end_matches(|c: char| c.is_whitespace()),
               " \t  a");
    assert_eq!(" \t  a \t  ".trim_matches(|c: char| c.is_whitespace()),
                    "a");
    assert_eq!(" \t   \t  ".trim_start_matches(|c: char| c.is_whitespace()),
                         "");
    assert_eq!(" \t   \t  ".trim_end_matches(|c: char| c.is_whitespace()),
               "");
    assert_eq!(" \t   \t  ".trim_start_matches(|c: char| c.is_whitespace()),
                         "");
    assert_eq!(" \t   \t  ".trim_end_matches(|c: char| c.is_whitespace()),
               "");
    assert_eq!(" \t   \t  ".trim_matches(|c: char| c.is_whitespace()),
               "");
}

#[test]
fn to_lowercase() {
    assert_eq!("".to_lowercase(), "");
    assert_eq!("AÉDžaé ".to_lowercase(), "aédžaé ");

    // https://github.com/rust-lang/rust/issues/26035
    assert_eq!("ΑΣ".to_lowercase(), "ας");
    assert_eq!("Α'Σ".to_lowercase(), "α'ς");
    assert_eq!("Α''Σ".to_lowercase(), "α''ς");

    assert_eq!("ΑΣ Α".to_lowercase(), "ας α");
    assert_eq!("Α'Σ Α".to_lowercase(), "α'ς α");
    assert_eq!("Α''Σ Α".to_lowercase(), "α''ς α");

    assert_eq!("ΑΣ' Α".to_lowercase(), "ας' α");
    assert_eq!("ΑΣ'' Α".to_lowercase(), "ας'' α");

    assert_eq!("Α'Σ' Α".to_lowercase(), "α'ς' α");
    assert_eq!("Α''Σ'' Α".to_lowercase(), "α''ς'' α");

    assert_eq!("Α Σ".to_lowercase(), "α σ");
    assert_eq!("Α 'Σ".to_lowercase(), "α 'σ");
    assert_eq!("Α ''Σ".to_lowercase(), "α ''σ");

    assert_eq!("Σ".to_lowercase(), "σ");
    assert_eq!("'Σ".to_lowercase(), "'σ");
    assert_eq!("''Σ".to_lowercase(), "''σ");

    assert_eq!("ΑΣΑ".to_lowercase(), "ασα");
    assert_eq!("ΑΣ'Α".to_lowercase(), "ασ'α");
    assert_eq!("ΑΣ''Α".to_lowercase(), "ασ''α");
}

#[test]
fn to_uppercase() {
    assert_eq!("".to_uppercase(), "");
    assert_eq!("aéDžßfiᾀ".to_uppercase(), "AÉDŽSSFIἈΙ");
}

#[test]
fn test_into_string() {
    // The only way to acquire a Box<str> in the first place is through a String, so just
    // test that we can round-trip between Box<str> and String.
    let string = String::from("Some text goes here");
    assert_eq!(string.clone().into_boxed_str().into_string(), string);
}

#[test]
fn test_box_slice_clone() {
    let data = String::from("hello HELLO hello HELLO yes YES 5 中ä华!!!");
    let data2 = data.clone().into_boxed_str().clone().into_string();

    assert_eq!(data, data2);
}

#[test]
fn test_cow_from() {
    let borrowed = "borrowed";
    let owned = String::from("owned");
    match (Cow::from(owned.clone()), Cow::from(borrowed)) {
        (Cow::Owned(o), Cow::Borrowed(b)) => assert!(o == owned && b == borrowed),
        _ => panic!("invalid `Cow::from`"),
    }
}

#[test]
fn test_repeat() {
    assert_eq!("".repeat(3), "");
    assert_eq!("abc".repeat(0), "");
    assert_eq!("α".repeat(3), "ααα");
}

mod pattern {
    use std::str::pattern::{Pattern, Searcher, ReverseSearcher};
    use std::str::pattern::SearchStep::{self, Match, Reject, Done};

    macro_rules! make_test {
        ($name:ident, $p:expr, $h:expr, [$($e:expr,)*]) => {
            #[allow(unused_imports)]
            mod $name {
                use std::str::pattern::SearchStep::{Match, Reject};
                use super::{cmp_search_to_vec};
                #[test]
                fn fwd() {
                    cmp_search_to_vec(false, $p, $h, vec![$($e),*]);
                }
                #[test]
                fn bwd() {
                    cmp_search_to_vec(true, $p, $h, vec![$($e),*]);
                }
            }
        }
    }

    fn cmp_search_to_vec<'a, P: Pattern<'a>>(rev: bool, pat: P, haystack: &'a str,
                                             right: Vec<SearchStep>)
    where P::Searcher: ReverseSearcher<'a>
    {
        let mut searcher = pat.into_searcher(haystack);
        let mut v = vec![];
        loop {
            match if !rev {searcher.next()} else {searcher.next_back()} {
                Match(a, b) => v.push(Match(a, b)),
                Reject(a, b) => v.push(Reject(a, b)),
                Done => break,
            }
        }
        if rev {
            v.reverse();
        }

        let mut first_index = 0;
        let mut err = None;

        for (i, e) in right.iter().enumerate() {
            match *e {
                Match(a, b) | Reject(a, b)
                if a <= b && a == first_index => {
                    first_index = b;
                }
                _ => {
                    err = Some(i);
                    break;
                }
            }
        }

        if let Some(err) = err {
            panic!("Input skipped range at {}", err);
        }

        if first_index != haystack.len() {
            panic!("Did not cover whole input");
        }

        assert_eq!(v, right);
    }

    make_test!(str_searcher_ascii_haystack, "bb", "abbcbbd", [
        Reject(0, 1),
        Match (1, 3),
        Reject(3, 4),
        Match (4, 6),
        Reject(6, 7),
    ]);
    make_test!(str_searcher_ascii_haystack_seq, "bb", "abbcbbbbd", [
        Reject(0, 1),
        Match (1, 3),
        Reject(3, 4),
        Match (4, 6),
        Match (6, 8),
        Reject(8, 9),
    ]);
    make_test!(str_searcher_empty_needle_ascii_haystack, "", "abbcbbd", [
        Match (0, 0),
        Reject(0, 1),
        Match (1, 1),
        Reject(1, 2),
        Match (2, 2),
        Reject(2, 3),
        Match (3, 3),
        Reject(3, 4),
        Match (4, 4),
        Reject(4, 5),
        Match (5, 5),
        Reject(5, 6),
        Match (6, 6),
        Reject(6, 7),
        Match (7, 7),
    ]);
    make_test!(str_searcher_multibyte_haystack, " ", "├──", [
        Reject(0, 3),
        Reject(3, 6),
        Reject(6, 9),
    ]);
    make_test!(str_searcher_empty_needle_multibyte_haystack, "", "├──", [
        Match (0, 0),
        Reject(0, 3),
        Match (3, 3),
        Reject(3, 6),
        Match (6, 6),
        Reject(6, 9),
        Match (9, 9),
    ]);
    make_test!(str_searcher_empty_needle_empty_haystack, "", "", [
        Match(0, 0),
    ]);
    make_test!(str_searcher_nonempty_needle_empty_haystack, "├", "", [
    ]);
    make_test!(char_searcher_ascii_haystack, 'b', "abbcbbd", [
        Reject(0, 1),
        Match (1, 2),
        Match (2, 3),
        Reject(3, 4),
        Match (4, 5),
        Match (5, 6),
        Reject(6, 7),
    ]);
    make_test!(char_searcher_multibyte_haystack, ' ', "├──", [
        Reject(0, 3),
        Reject(3, 6),
        Reject(6, 9),
    ]);
    make_test!(char_searcher_short_haystack, '\u{1F4A9}', "* \t", [
        Reject(0, 1),
        Reject(1, 2),
        Reject(2, 3),
    ]);

}

macro_rules! generate_iterator_test {
    {
        $name:ident {
            $(
                ($($arg:expr),*) -> [$($t:tt)*];
            )*
        }
        with $fwd:expr, $bwd:expr;
    } => {
        #[test]
        fn $name() {
            $(
                {
                    let res = vec![$($t)*];

                    let fwd_vec: Vec<_> = ($fwd)($($arg),*).collect();
                    assert_eq!(fwd_vec, res);

                    let mut bwd_vec: Vec<_> = ($bwd)($($arg),*).collect();
                    bwd_vec.reverse();
                    assert_eq!(bwd_vec, res);
                }
            )*
        }
    };
    {
        $name:ident {
            $(
                ($($arg:expr),*) -> [$($t:tt)*];
            )*
        }
        with $fwd:expr;
    } => {
        #[test]
        fn $name() {
            $(
                {
                    let res = vec![$($t)*];

                    let fwd_vec: Vec<_> = ($fwd)($($arg),*).collect();
                    assert_eq!(fwd_vec, res);
                }
            )*
        }
    }
}

generate_iterator_test! {
    double_ended_split {
        ("foo.bar.baz", '.') -> ["foo", "bar", "baz"];
        ("foo::bar::baz", "::") -> ["foo", "bar", "baz"];
    }
    with str::split, str::rsplit;
}

generate_iterator_test! {
    double_ended_split_terminator {
        ("foo;bar;baz;", ';') -> ["foo", "bar", "baz"];
    }
    with str::split_terminator, str::rsplit_terminator;
}

generate_iterator_test! {
    double_ended_matches {
        ("a1b2c3", char::is_numeric) -> ["1", "2", "3"];
    }
    with str::matches, str::rmatches;
}

generate_iterator_test! {
    double_ended_match_indices {
        ("a1b2c3", char::is_numeric) -> [(1, "1"), (3, "2"), (5, "3")];
    }
    with str::match_indices, str::rmatch_indices;
}

generate_iterator_test! {
    not_double_ended_splitn {
        ("foo::bar::baz", 2, "::") -> ["foo", "bar::baz"];
    }
    with str::splitn;
}

generate_iterator_test! {
    not_double_ended_rsplitn {
        ("foo::bar::baz", 2, "::") -> ["baz", "foo::bar"];
    }
    with str::rsplitn;
}

#[test]
fn different_str_pattern_forwarding_lifetimes() {
    use std::str::pattern::Pattern;

    fn foo<'a, P>(p: P) where for<'b> &'b P: Pattern<'a> {
        for _ in 0..3 {
            "asdf".find(&p);
        }
    }

    foo::<&str>("x");
}