lib.rs

// Copyright 2013-2014 The Rust Project Developers.
// Copyright 2018 The Uuid Project Developers.
//
// See the COPYRIGHT file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! Generate and parse UUIDs.
//!
//! Provides support for Universally Unique Identifiers (UUIDs). A UUID is a
//! unique 128-bit number, stored as 16 octets. UUIDs are used to  assign
//! unique identifiers to entities without requiring a central allocating
//! authority.
//!
//! They are particularly useful in distributed systems, though can be used in
//! disparate areas, such as databases and network protocols.  Typically a UUID
//! is displayed in a readable string form as a sequence of hexadecimal digits,
//! separated into groups by hyphens.
//!
//! The uniqueness property is not strictly guaranteed, however for all
//! practical purposes, it can be assumed that an unintentional collision would
//! be extremely unlikely.
//!
//! # Dependencies
//!
//! By default, this crate depends on nothing but `std` and cannot generate
//! UUIDs. You need to enable the following Cargo features to enable
//! various pieces of functionality:
//!
//! * `v1` - adds the [`Uuid::new_v1`] function and the ability to create a V1
//!   using an implementation of [`v1::ClockSequence`] (usually
//! [`v1::Context`]) and a timestamp from `time::timespec`.
//! * `v3` - adds the [`Uuid::new_v3`] function and the ability to create a V3
//!   UUID based on the MD5 hash of some data.
//! * `v4` - adds the [`Uuid::new_v4`] function and the ability to randomly
//!   generate a UUID.
//! * `v5` - adds the [`Uuid::new_v5`] function and the ability to create a V5
//!   UUID based on the SHA1 hash of some data.
//! * `serde` - adds the ability to serialize and deserialize a UUID using the
//!   `serde` crate.
//!
//! You need to enable one of the following Cargo features together with
//! `v3`, `v4` or `v5` feature if you're targeting `wasm32-unknown-unknown`
//! target:
//!
//! * `stdweb` - enables support for `OsRng` on `wasm32-unknown-unknown` via
//!   [`stdweb`] combined with [`cargo-web`]
//! * `wasm-bindgen` - enables support for `OsRng` on `wasm32-unknown-unknown`
//!   via [`wasm-bindgen`]
//!
//! By default, `uuid` can be depended on with:
//!
//! ```toml
//! [dependencies]
//! uuid = "0.8"
//! ```
//!
//! To activate various features, use syntax like:
//!
//! ```toml
//! [dependencies]
//! uuid = { version = "0.8", features = ["serde", "v4"] }
//! ```
//!
//! You can disable default features with:
//!
//! ```toml
//! [dependencies]
//! uuid = { version = "0.8", default-features = false }
//! ```
//!
//! # Examples
//!
//! To parse a UUID given in the simple format and print it as a urn:
//!
//! ```rust
//! use uuid::Uuid;
//!
//! fn main() -> Result<(), uuid::Error> {
//!     let my_uuid =
//!         Uuid::parse_str("936DA01F9ABD4d9d80C702AF85C822A8")?;
//!     println!("{}", my_uuid.to_urn());
//!     Ok(())
//! }
//! ```
//!
//! To create a new random (V4) UUID and print it out in hexadecimal form:
//!
//! ```ignore,rust
//! // Note that this requires the `v4` feature enabled in the uuid crate.
//!
//! use uuid::Uuid;
//!
//! fn main() -> Result<(), Box<dyn std::error::Error>> {
//!     #[cfg(feature = "v4")] {
//!         let my_uuid = Uuid::new_v4()?;
//!         println!("{}", my_uuid);
//!     }
//!     Ok(())
//! }
//! ```
//!
//! # Strings
//!
//! Examples of string representations:
//!
//! * simple: `936DA01F9ABD4d9d80C702AF85C822A8`
//! * hyphenated: `550e8400-e29b-41d4-a716-446655440000`
//! * urn: `urn:uuid:F9168C5E-CEB2-4faa-B6BF-329BF39FA1E4`
//!
//! # References
//!
//! * [Wikipedia: Universally Unique Identifier](http://en.wikipedia.org/wiki/Universally_unique_identifier)
//! * [RFC4122: A Universally Unique IDentifier (UUID) URN Namespace](http://tools.ietf.org/html/rfc4122)
//!
//! [`wasm-bindgen`]: https://crates.io/crates/wasm-bindgen
//! [`cargo-web`]: https://crates.io/crates/cargo-web
//! [`stdweb`]: https://crates.io/crates/stdweb
//! [`Uuid`]: struct.Uuid.html
//! [`Uuid::new_v1`]: struct.Uuid.html#method.new_v1
//! [`Uuid::new_v3`]: struct.Uuid.html#method.new_v3
//! [`Uuid::new_v4`]: struct.Uuid.html#method.new_v4
//! [`Uuid::new_v5`]: struct.Uuid.html#method.new_v5
//! [`v1::ClockSequence`]: v1/trait.ClockSequence.html
//! [`v1::Context`]: v1/struct.Context.html

#![no_std]
#![deny(missing_debug_implementations, missing_docs)]
#![doc(
    html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
    html_favicon_url = "https://www.rust-lang.org/favicon.ico",
    html_root_url = "https://docs.rs/uuid/0.8.1"
)]

#[cfg(any(feature = "std", test))]
#[macro_use]
extern crate std;

#[cfg(all(not(feature = "std"), not(test)))]
#[macro_use]
extern crate core as std;

mod builder;
mod error;
mod parser;
mod prelude;

pub mod adapter;
#[cfg(feature = "v1")]
pub mod v1;

#[cfg(feature = "serde")]
mod serde_support;
#[cfg(feature = "slog")]
mod slog_support;
#[cfg(test)]
mod test_util;
#[cfg(all(
    feature = "v3",
    any(
        not(target_arch = "wasm32"),
        target_os = "wasi",
        all(
            target_arch = "wasm32",
            any(feature = "stdweb", feature = "wasm-bindgen")
        )
    )
))]
mod v3;
#[cfg(all(
    feature = "v4",
    any(
        not(target_arch = "wasm32"),
        target_os = "wasi",
        all(
            target_arch = "wasm32",
            any(feature = "stdweb", feature = "wasm-bindgen")
        )
    )
))]
mod v4;
#[cfg(all(
    feature = "v5",
    any(
        not(target_arch = "wasm32"),
        target_os = "wasi",
        all(
            target_arch = "wasm32",
            any(feature = "stdweb", feature = "wasm-bindgen")
        )
    )
))]
mod v5;
#[cfg(all(windows, feature = "winapi"))]
mod winapi_support;

use crate::std::{convert::TryInto, fmt, str};

pub use crate::error::Error;

/// A builder struct for creating a UUID.
///
/// # Examples
///
/// Creating a v4 UUID from externally generated bytes:
///
/// ```
/// use uuid::{Builder, Variant, Version};
///
/// # let rng = || [
/// #     70, 235, 208, 238, 14, 109, 67, 201, 185, 13, 204, 195, 90,
/// # 145, 63, 62,
/// # ];
/// let random_bytes = rng();
/// let uuid = Builder::from_bytes(random_bytes)
///     .set_variant(Variant::RFC4122)
///     .set_version(Version::Random)
///     .build();
/// ```
#[allow(missing_copy_implementations)]
#[derive(Debug)]
pub struct Builder(Bytes);

/// A 128-bit (16 byte) buffer containing the ID.
pub type Bytes = [u8; 16];

/// The version of the UUID, denoting the generating algorithm.
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum Version {
    /// Special case for `nil` UUID.
    Nil = 0,
    /// Version 1: MAC address.
    Mac,
    /// Version 2: DCE Security.
    Dce,
    /// Version 3: MD5 hash.
    Md5,
    /// Version 4: Random.
    Random,
    /// Version 5: SHA-1 hash.
    Sha1,
}

/// The reserved variants of UUIDs.
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum Variant {
    /// Reserved by the NCS for backward compatibility.
    NCS = 0,
    /// As described in the RFC4122 Specification (default).
    RFC4122,
    /// Reserved by Microsoft for backward compatibility.
    Microsoft,
    /// Reserved for future expansion.
    Future,
}

/// A Universally Unique Identifier (UUID).
#[derive(Clone, Copy, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[repr(transparent)]
pub struct Uuid(Bytes);

impl Uuid {
    /// UUID namespace for Domain Name System (DNS).
    pub const NAMESPACE_DNS: Self = Uuid([
        0x6b, 0xa7, 0xb8, 0x10, 0x9d, 0xad, 0x11, 0xd1, 0x80, 0xb4, 0x00, 0xc0,
        0x4f, 0xd4, 0x30, 0xc8,
    ]);

    /// UUID namespace for ISO Object Identifiers (OIDs).
    pub const NAMESPACE_OID: Self = Uuid([
        0x6b, 0xa7, 0xb8, 0x12, 0x9d, 0xad, 0x11, 0xd1, 0x80, 0xb4, 0x00, 0xc0,
        0x4f, 0xd4, 0x30, 0xc8,
    ]);

    /// UUID namespace for Uniform Resource Locators (URLs).
    pub const NAMESPACE_URL: Self = Uuid([
        0x6b, 0xa7, 0xb8, 0x11, 0x9d, 0xad, 0x11, 0xd1, 0x80, 0xb4, 0x00, 0xc0,
        0x4f, 0xd4, 0x30, 0xc8,
    ]);

    /// UUID namespace for X.500 Distinguished Names (DNs).
    pub const NAMESPACE_X500: Self = Uuid([
        0x6b, 0xa7, 0xb8, 0x14, 0x9d, 0xad, 0x11, 0xd1, 0x80, 0xb4, 0x00, 0xc0,
        0x4f, 0xd4, 0x30, 0xc8,
    ]);

    /// Returns the variant of the UUID structure.
    ///
    /// This determines the interpretation of the structure of the UUID.
    /// Currently only the RFC4122 variant is generated by this module.
    ///
    /// * [Variant Reference](http://tools.ietf.org/html/rfc4122#section-4.1.1)
    pub fn get_variant(&self) -> Option<Variant> {
        match self.as_bytes()[8] {
            x if x & 0x80 == 0x00 => Some(Variant::NCS),
            x if x & 0xc0 == 0x80 => Some(Variant::RFC4122),
            x if x & 0xe0 == 0xc0 => Some(Variant::Microsoft),
            x if x & 0xe0 == 0xe0 => Some(Variant::Future),
            _ => None,
        }
    }

    /// Returns the version number of the UUID.
    ///
    /// This represents the algorithm used to generate the contents.
    ///
    /// Currently only the Random (V4) algorithm is supported by this
    /// module.  There are security and privacy implications for using
    /// older versions - see [Wikipedia: Universally Unique Identifier](
    /// http://en.wikipedia.org/wiki/Universally_unique_identifier) for
    /// details.
    ///
    /// * [Version Reference](http://tools.ietf.org/html/rfc4122#section-4.1.3)
    pub const fn get_version_num(&self) -> usize {
        (self.as_bytes()[6] >> 4) as usize
    }

    /// Returns the version of the UUID.
    ///
    /// This represents the algorithm used to generate the contents
    pub fn get_version(&self) -> Option<Version> {
        let v = self.as_bytes()[6] >> 4;
        match v {
            0 if self.is_nil() => Some(Version::Nil),
            1 => Some(Version::Mac),
            2 => Some(Version::Dce),
            3 => Some(Version::Md5),
            4 => Some(Version::Random),
            5 => Some(Version::Sha1),
            _ => None,
        }
    }

    /// Returns the four field values of the UUID in big-endian order.
    ///
    /// These values can be passed to the `from_fields()` method to get the
    /// original `Uuid` back.
    ///
    /// * The first field value represents the first group of (eight) hex
    ///   digits, taken as a big-endian `u32` value.  For V1 UUIDs, this field
    ///   represents the low 32 bits of the timestamp.
    /// * The second field value represents the second group of (four) hex
    ///   digits, taken as a big-endian `u16` value.  For V1 UUIDs, this field
    ///   represents the middle 16 bits of the timestamp.
    /// * The third field value represents the third group of (four) hex digits,
    ///   taken as a big-endian `u16` value.  The 4 most significant bits give
    ///   the UUID version, and for V1 UUIDs, the last 12 bits represent the
    ///   high 12 bits of the timestamp.
    /// * The last field value represents the last two groups of four and twelve
    ///   hex digits, taken in order.  The first 1-3 bits of this indicate the
    ///   UUID variant, and for V1 UUIDs, the next 13-15 bits indicate the clock
    ///   sequence and the last 48 bits indicate the node ID.
    ///
    /// # Examples
    ///
    /// ```
    /// use uuid::Uuid;
    ///
    /// fn main() -> Result<(), uuid::Error> {
    ///     let uuid = Uuid::nil();
    ///     assert_eq!(uuid.as_fields(), (0, 0, 0, &[0u8; 8]));
    ///
    ///     let uuid = Uuid::parse_str("936DA01F-9ABD-4D9D-80C7-02AF85C822A8")?;
    ///     assert_eq!(
    ///         uuid.as_fields(),
    ///         (
    ///             0x936DA01F,
    ///             0x9ABD,
    ///             0x4D9D,
    ///             b"\x80\xC7\x02\xAF\x85\xC8\x22\xA8"
    ///         )
    ///     );
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn as_fields(&self) -> (u32, u16, u16, &[u8; 8]) {
        let d1 = u32::from(self.as_bytes()[0]) << 24
            | u32::from(self.as_bytes()[1]) << 16
            | u32::from(self.as_bytes()[2]) << 8
            | u32::from(self.as_bytes()[3]);

        let d2 =
            u16::from(self.as_bytes()[4]) << 8 | u16::from(self.as_bytes()[5]);

        let d3 =
            u16::from(self.as_bytes()[6]) << 8 | u16::from(self.as_bytes()[7]);

        let d4: &[u8; 8] = self.as_bytes()[8..16].try_into().unwrap();
        (d1, d2, d3, d4)
    }

    /// Returns the four field values of the UUID in little-endian order.
    ///
    /// The bytes in the returned integer fields will
    /// be converted from big-endian order.
    ///
    /// # Examples
    ///
    /// ```
    /// use uuid::Uuid;
    ///
    /// fn main() -> Result<(), uuid::Error> {
    ///     let uuid = Uuid::parse_str("936DA01F-9ABD-4D9D-80C7-02AF85C822A8")?;
    ///     assert_eq!(
    ///         uuid.to_fields_le(),
    ///         (
    ///             0x1FA06D93,
    ///             0xBD9A,
    ///             0x9D4D,
    ///             b"\x80\xC7\x02\xAF\x85\xC8\x22\xA8"
    ///         )
    ///     );
    ///     Ok(())
    /// }
    /// ```
    pub fn to_fields_le(&self) -> (u32, u16, u16, &[u8; 8]) {
        let d1 = u32::from(self.as_bytes()[0])
            | u32::from(self.as_bytes()[1]) << 8
            | u32::from(self.as_bytes()[2]) << 16
            | u32::from(self.as_bytes()[3]) << 24;

        let d2 =
            u16::from(self.as_bytes()[4]) | u16::from(self.as_bytes()[5]) << 8;

        let d3 =
            u16::from(self.as_bytes()[6]) | u16::from(self.as_bytes()[7]) << 8;

        let d4: &[u8; 8] = self.as_bytes()[8..16].try_into().unwrap();
        (d1, d2, d3, d4)
    }

    /// Returns a 128bit value containing the UUID data.
    ///
    /// The bytes in the UUID will be packed into a `u128`, like the
    /// [`Uuid::as_bytes`] method.
    ///
    /// # Examples
    ///
    /// ```
    /// use uuid::Uuid;
    ///
    /// fn main() -> Result<(), uuid::Error> {
    ///     let uuid = Uuid::parse_str("936DA01F-9ABD-4D9D-80C7-02AF85C822A8")?;
    ///     assert_eq!(
    ///         uuid.as_u128(),
    ///         0x936DA01F9ABD4D9D80C702AF85C822A8,
    ///     );
    ///     Ok(())
    /// }
    /// ```
    pub fn as_u128(&self) -> u128 {
        u128::from(self.as_bytes()[0]) << 120
            | u128::from(self.as_bytes()[1]) << 112
            | u128::from(self.as_bytes()[2]) << 104
            | u128::from(self.as_bytes()[3]) << 96
            | u128::from(self.as_bytes()[4]) << 88
            | u128::from(self.as_bytes()[5]) << 80
            | u128::from(self.as_bytes()[6]) << 72
            | u128::from(self.as_bytes()[7]) << 64
            | u128::from(self.as_bytes()[8]) << 56
            | u128::from(self.as_bytes()[9]) << 48
            | u128::from(self.as_bytes()[10]) << 40
            | u128::from(self.as_bytes()[11]) << 32
            | u128::from(self.as_bytes()[12]) << 24
            | u128::from(self.as_bytes()[13]) << 16
            | u128::from(self.as_bytes()[14]) << 8
            | u128::from(self.as_bytes()[15])
    }

    /// Returns a 128bit little-endian value containing the UUID data.
    ///
    /// The bytes in the UUID will be reversed and packed into a `u128`.
    /// Note that this will produce a different result than
    /// [`Uuid::to_fields_le`], because the entire UUID is reversed, rather
    /// than reversing the individual fields in-place.
    ///
    /// # Examples
    ///
    /// ```
    /// use uuid::Uuid;
    ///
    /// fn main() -> Result<(), uuid::Error> {
    ///     let uuid = Uuid::parse_str("936DA01F-9ABD-4D9D-80C7-02AF85C822A8")?;
    ///
    ///     assert_eq!(
    ///         uuid.to_u128_le(),
    ///         0xA822C885AF02C7809D4DBD9A1FA06D93,
    ///     );
    ///     Ok(())
    /// }
    /// ```
    pub fn to_u128_le(&self) -> u128 {
        u128::from(self.as_bytes()[0])
            | u128::from(self.as_bytes()[1]) << 8
            | u128::from(self.as_bytes()[2]) << 16
            | u128::from(self.as_bytes()[3]) << 24
            | u128::from(self.as_bytes()[4]) << 32
            | u128::from(self.as_bytes()[5]) << 40
            | u128::from(self.as_bytes()[6]) << 48
            | u128::from(self.as_bytes()[7]) << 56
            | u128::from(self.as_bytes()[8]) << 64
            | u128::from(self.as_bytes()[9]) << 72
            | u128::from(self.as_bytes()[10]) << 80
            | u128::from(self.as_bytes()[11]) << 88
            | u128::from(self.as_bytes()[12]) << 96
            | u128::from(self.as_bytes()[13]) << 104
            | u128::from(self.as_bytes()[14]) << 112
            | u128::from(self.as_bytes()[15]) << 120
    }

    /// Returns an array of 16 octets containing the UUID data.
    pub const fn as_bytes(&self) -> &Bytes {
        &self.0
    }

    /// Tests if the UUID is nil.
    pub fn is_nil(&self) -> bool {
        self.as_bytes().iter().all(|&b| b == 0)
    }

    /// A buffer that can be used for `encode_...` calls, that is
    /// guaranteed to be long enough for any of the adapters.
    ///
    /// # Examples
    ///
    /// ```rust
    /// use uuid::Uuid;
    ///
    /// let uuid = Uuid::nil();
    ///
    /// assert_eq!(
    ///     uuid.to_simple().encode_lower(&mut Uuid::encode_buffer()),
    ///     "00000000000000000000000000000000"
    /// );
    ///
    /// assert_eq!(
    ///     uuid.to_hyphenated()
    ///         .encode_lower(&mut Uuid::encode_buffer()),
    ///     "00000000-0000-0000-0000-000000000000"
    /// );
    ///
    /// assert_eq!(
    ///     uuid.to_urn().encode_lower(&mut Uuid::encode_buffer()),
    ///     "urn:uuid:00000000-0000-0000-0000-000000000000"
    /// );
    /// ```
    pub const fn encode_buffer() -> [u8; adapter::Urn::LENGTH] {
        [0; adapter::Urn::LENGTH]
    }
}

impl fmt::Debug for Uuid {
    #[inline]
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::LowerHex::fmt(self, f)
    }
}

impl fmt::Display for Uuid {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::LowerHex::fmt(self, f)
    }
}

impl fmt::Display for Variant {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match *self {
            Variant::NCS => write!(f, "NCS"),
            Variant::RFC4122 => write!(f, "RFC4122"),
            Variant::Microsoft => write!(f, "Microsoft"),
            Variant::Future => write!(f, "Future"),
        }
    }
}

impl fmt::LowerHex for Uuid {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::LowerHex::fmt(&self.to_hyphenated_ref(), f)
    }
}

impl fmt::UpperHex for Uuid {
    #[inline]
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::UpperHex::fmt(&self.to_hyphenated_ref(), f)
    }
}

impl str::FromStr for Uuid {
    type Err = Error;

    fn from_str(uuid_str: &str) -> Result<Self, Self::Err> {
        Uuid::parse_str(uuid_str)
    }
}

impl Default for Uuid {
    #[inline]
    fn default() -> Self {
        Uuid::nil()
    }
}

#[cfg(test)]
mod tests {
    use crate::{
        prelude::*,
        std::string::{String, ToString},
        test_util,
    };

    macro_rules! check {
        ($buf:ident, $format:expr, $target:expr, $len:expr, $cond:expr) => {
            $buf.clear();
            write!($buf, $format, $target).unwrap();
            assert!($buf.len() == $len);
            assert!($buf.chars().all($cond), "{}", $buf);
        };
    }

    #[test]
    fn test_uuid_compare() {
        let uuid1 = test_util::new();
        let uuid2 = test_util::new2();

        assert_eq!(uuid1, uuid1);
        assert_eq!(uuid2, uuid2);

        assert_ne!(uuid1, uuid2);
        assert_ne!(uuid2, uuid1);
    }

    #[test]
    fn test_uuid_default() {
        let default_uuid = Uuid::default();
        let nil_uuid = Uuid::nil();

        assert_eq!(default_uuid, nil_uuid);
    }

    #[test]
    fn test_uuid_display() {
        use super::fmt::Write;

        let uuid = test_util::new();
        let s = uuid.to_string();
        let mut buffer = String::new();

        assert_eq!(s, uuid.to_hyphenated().to_string());

        check!(buffer, "{}", uuid, 36, |c| c.is_lowercase()
            || c.is_digit(10)
            || c == '-');
    }

    #[test]
    fn test_uuid_lowerhex() {
        use super::fmt::Write;

        let mut buffer = String::new();
        let uuid = test_util::new();

        check!(buffer, "{:x}", uuid, 36, |c| c.is_lowercase()
            || c.is_digit(10)
            || c == '-');
    }

    // noinspection RsAssertEqual
    #[test]
    fn test_uuid_operator_eq() {
        let uuid1 = test_util::new();
        let uuid1_dup = uuid1.clone();
        let uuid2 = test_util::new2();

        assert!(uuid1 == uuid1);
        assert!(uuid1 == uuid1_dup);
        assert!(uuid1_dup == uuid1);

        assert!(uuid1 != uuid2);
        assert!(uuid2 != uuid1);
        assert!(uuid1_dup != uuid2);
        assert!(uuid2 != uuid1_dup);
    }

    #[test]
    fn test_uuid_to_string() {
        use super::fmt::Write;

        let uuid = test_util::new();
        let s = uuid.to_string();
        let mut buffer = String::new();

        assert_eq!(s.len(), 36);

        check!(buffer, "{}", s, 36, |c| c.is_lowercase()
            || c.is_digit(10)
            || c == '-');
    }

    #[test]
    fn test_uuid_upperhex() {
        use super::fmt::Write;

        let mut buffer = String::new();
        let uuid = test_util::new();

        check!(buffer, "{:X}", uuid, 36, |c| c.is_uppercase()
            || c.is_digit(10)
            || c == '-');
    }

    #[test]
    fn test_nil() {
        let nil = Uuid::nil();
        let not_nil = test_util::new();
        let from_bytes = Uuid::from_bytes([
            4, 54, 67, 12, 43, 2, 2, 76, 32, 50, 87, 5, 1, 33, 43, 87,
        ]);

        assert_eq!(from_bytes.get_version(), None);

        assert!(nil.is_nil());
        assert!(!not_nil.is_nil());

        assert_eq!(nil.get_version(), Some(Version::Nil));
        assert_eq!(not_nil.get_version(), Some(Version::Random))
    }

    #[test]
    fn test_predefined_namespaces() {
        assert_eq!(
            Uuid::NAMESPACE_DNS.to_hyphenated().to_string(),
            "6ba7b810-9dad-11d1-80b4-00c04fd430c8"
        );
        assert_eq!(
            Uuid::NAMESPACE_URL.to_hyphenated().to_string(),
            "6ba7b811-9dad-11d1-80b4-00c04fd430c8"
        );
        assert_eq!(
            Uuid::NAMESPACE_OID.to_hyphenated().to_string(),
            "6ba7b812-9dad-11d1-80b4-00c04fd430c8"
        );
        assert_eq!(
            Uuid::NAMESPACE_X500.to_hyphenated().to_string(),
            "6ba7b814-9dad-11d1-80b4-00c04fd430c8"
        );
    }

    #[cfg(feature = "v3")]
    #[test]
    fn test_get_version_v3() {
        let uuid =
            Uuid::new_v3(&Uuid::NAMESPACE_DNS, "rust-lang.org".as_bytes());

        assert_eq!(uuid.get_version().unwrap(), Version::Md5);
        assert_eq!(uuid.get_version_num(), 3);
    }

    #[test]
    fn test_get_variant() {
        let uuid1 = test_util::new();
        let uuid2 =
            Uuid::parse_str("550e8400-e29b-41d4-a716-446655440000").unwrap();
        let uuid3 =
            Uuid::parse_str("67e55044-10b1-426f-9247-bb680e5fe0c8").unwrap();
        let uuid4 =
            Uuid::parse_str("936DA01F9ABD4d9dC0C702AF85C822A8").unwrap();
        let uuid5 =
            Uuid::parse_str("F9168C5E-CEB2-4faa-D6BF-329BF39FA1E4").unwrap();
        let uuid6 =
            Uuid::parse_str("f81d4fae-7dec-11d0-7765-00a0c91e6bf6").unwrap();

        assert_eq!(uuid1.get_variant().unwrap(), Variant::RFC4122);
        assert_eq!(uuid2.get_variant().unwrap(), Variant::RFC4122);
        assert_eq!(uuid3.get_variant().unwrap(), Variant::RFC4122);
        assert_eq!(uuid4.get_variant().unwrap(), Variant::Microsoft);
        assert_eq!(uuid5.get_variant().unwrap(), Variant::Microsoft);
        assert_eq!(uuid6.get_variant().unwrap(), Variant::NCS);
    }

    #[test]
    fn test_to_simple_string() {
        let uuid1 = test_util::new();
        let s = uuid1.to_simple().to_string();

        assert_eq!(s.len(), 32);
        assert!(s.chars().all(|c| c.is_digit(16)));
    }

    #[test]
    fn test_to_hyphenated_string() {
        let uuid1 = test_util::new();
        let s = uuid1.to_hyphenated().to_string();

        assert!(s.len() == 36);
        assert!(s.chars().all(|c| c.is_digit(16) || c == '-'));
    }

    #[test]
    fn test_upper_lower_hex() {
        use std::fmt::Write;

        let mut buf = String::new();
        let u = test_util::new();

        macro_rules! check {
            ($buf:ident, $format:expr, $target:expr, $len:expr, $cond:expr) => {
                $buf.clear();
                write!($buf, $format, $target).unwrap();
                assert!(buf.len() == $len);
                assert!($buf.chars().all($cond), "{}", $buf);
            };
        }

        check!(buf, "{:X}", u, 36, |c| c.is_uppercase()
            || c.is_digit(10)
            || c == '-');
        check!(buf, "{:X}", u.to_hyphenated(), 36, |c| c.is_uppercase()
            || c.is_digit(10)
            || c == '-');
        check!(buf, "{:X}", u.to_simple(), 32, |c| c.is_uppercase()
            || c.is_digit(10));

        check!(buf, "{:x}", u.to_hyphenated(), 36, |c| c.is_lowercase()
            || c.is_digit(10)
            || c == '-');
        check!(buf, "{:x}", u.to_simple(), 32, |c| c.is_lowercase()
            || c.is_digit(10));
    }

    #[test]
    fn test_to_urn_string() {
        let uuid1 = test_util::new();
        let ss = uuid1.to_urn().to_string();
        let s = &ss[9..];

        assert!(ss.starts_with("urn:uuid:"));
        assert_eq!(s.len(), 36);
        assert!(s.chars().all(|c| c.is_digit(16) || c == '-'));
    }

    #[test]
    fn test_to_simple_string_matching() {
        let uuid1 = test_util::new();

        let hs = uuid1.to_hyphenated().to_string();
        let ss = uuid1.to_simple().to_string();

        let hsn = hs.chars().filter(|&c| c != '-').collect::<String>();

        assert_eq!(hsn, ss);
    }

    #[test]
    fn test_string_roundtrip() {
        let uuid = test_util::new();

        let hs = uuid.to_hyphenated().to_string();
        let uuid_hs = Uuid::parse_str(&hs).unwrap();
        assert_eq!(uuid_hs, uuid);

        let ss = uuid.to_string();
        let uuid_ss = Uuid::parse_str(&ss).unwrap();
        assert_eq!(uuid_ss, uuid);
    }

    #[test]
    fn test_from_fields() {
        let d1: u32 = 0xa1a2a3a4;
        let d2: u16 = 0xb1b2;
        let d3: u16 = 0xc1c2;
        let d4 = [0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8];

        let u = Uuid::from_fields(d1, d2, d3, &d4).unwrap();

        let expected = "a1a2a3a4b1b2c1c2d1d2d3d4d5d6d7d8";
        let result = u.to_simple().to_string();
        assert_eq!(result, expected);
    }

    #[test]
    fn test_from_fields_le() {
        let d1: u32 = 0xa4a3a2a1;
        let d2: u16 = 0xb2b1;
        let d3: u16 = 0xc2c1;
        let d4 = [0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8];

        let u = Uuid::from_fields_le(d1, d2, d3, &d4).unwrap();

        let expected = "a1a2a3a4b1b2c1c2d1d2d3d4d5d6d7d8";
        let result = u.to_simple().to_string();
        assert_eq!(result, expected);
    }

    #[test]
    fn test_as_fields() {
        let u = test_util::new();
        let (d1, d2, d3, d4) = u.as_fields();

        assert_ne!(d1, 0);
        assert_ne!(d2, 0);
        assert_ne!(d3, 0);
        assert_eq!(d4.len(), 8);
        assert!(!d4.iter().all(|&b| b == 0));
    }

    #[test]
    fn test_fields_roundtrip() {
        let d1_in: u32 = 0xa1a2a3a4;
        let d2_in: u16 = 0xb1b2;
        let d3_in: u16 = 0xc1c2;
        let d4_in = &[0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8];

        let u = Uuid::from_fields(d1_in, d2_in, d3_in, d4_in).unwrap();
        let (d1_out, d2_out, d3_out, d4_out) = u.as_fields();

        assert_eq!(d1_in, d1_out);
        assert_eq!(d2_in, d2_out);
        assert_eq!(d3_in, d3_out);
        assert_eq!(d4_in, d4_out);
    }

    #[test]
    fn test_fields_le_roundtrip() {
        let d1_in: u32 = 0xa4a3a2a1;
        let d2_in: u16 = 0xb2b1;
        let d3_in: u16 = 0xc2c1;
        let d4_in = &[0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8];

        let u = Uuid::from_fields_le(d1_in, d2_in, d3_in, d4_in).unwrap();
        let (d1_out, d2_out, d3_out, d4_out) = u.to_fields_le();

        assert_eq!(d1_in, d1_out);
        assert_eq!(d2_in, d2_out);
        assert_eq!(d3_in, d3_out);
        assert_eq!(d4_in, d4_out);
    }

    #[test]
    fn test_fields_le_are_actually_le() {
        let d1_in: u32 = 0xa1a2a3a4;
        let d2_in: u16 = 0xb1b2;
        let d3_in: u16 = 0xc1c2;
        let d4_in = &[0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8];

        let u = Uuid::from_fields(d1_in, d2_in, d3_in, d4_in).unwrap();
        let (d1_out, d2_out, d3_out, d4_out) = u.to_fields_le();

        assert_eq!(d1_in, d1_out.swap_bytes());
        assert_eq!(d2_in, d2_out.swap_bytes());
        assert_eq!(d3_in, d3_out.swap_bytes());
        assert_eq!(d4_in, d4_out);
    }

    #[test]
    fn test_from_u128() {
        let v_in: u128 = 0xa1a2a3a4b1b2c1c2d1d2d3d4d5d6d7d8;

        let u = Uuid::from_u128(v_in);

        let expected = "a1a2a3a4b1b2c1c2d1d2d3d4d5d6d7d8";
        let result = u.to_simple().to_string();
        assert_eq!(result, expected);
    }

    #[test]
    fn test_from_u128_le() {
        let v_in: u128 = 0xd8d7d6d5d4d3d2d1c2c1b2b1a4a3a2a1;

        let u = Uuid::from_u128_le(v_in);

        let expected = "a1a2a3a4b1b2c1c2d1d2d3d4d5d6d7d8";
        let result = u.to_simple().to_string();
        assert_eq!(result, expected);
    }

    #[test]
    fn test_u128_roundtrip() {
        let v_in: u128 = 0xa1a2a3a4b1b2c1c2d1d2d3d4d5d6d7d8;

        let u = Uuid::from_u128(v_in);
        let v_out = u.as_u128();

        assert_eq!(v_in, v_out);
    }

    #[test]
    fn test_u128_le_roundtrip() {
        let v_in: u128 = 0xd8d7d6d5d4d3d2d1c2c1b2b1a4a3a2a1;

        let u = Uuid::from_u128_le(v_in);
        let v_out = u.to_u128_le();

        assert_eq!(v_in, v_out);
    }

    #[test]
    fn test_u128_le_is_actually_le() {
        let v_in: u128 = 0xa1a2a3a4b1b2c1c2d1d2d3d4d5d6d7d8;

        let u = Uuid::from_u128(v_in);
        let v_out = u.to_u128_le();

        assert_eq!(v_in, v_out.swap_bytes());
    }

    #[test]
    fn test_from_slice() {
        let b = [
            0xa1, 0xa2, 0xa3, 0xa4, 0xb1, 0xb2, 0xc1, 0xc2, 0xd1, 0xd2, 0xd3,
            0xd4, 0xd5, 0xd6, 0xd7, 0xd8,
        ];

        let u = Uuid::from_slice(&b).unwrap();
        let expected = "a1a2a3a4b1b2c1c2d1d2d3d4d5d6d7d8";

        assert_eq!(u.to_simple().to_string(), expected);
    }

    #[test]
    fn test_from_bytes() {
        let b = [
            0xa1, 0xa2, 0xa3, 0xa4, 0xb1, 0xb2, 0xc1, 0xc2, 0xd1, 0xd2, 0xd3,
            0xd4, 0xd5, 0xd6, 0xd7, 0xd8,
        ];

        let u = Uuid::from_bytes(b);
        let expected = "a1a2a3a4b1b2c1c2d1d2d3d4d5d6d7d8";

        assert_eq!(u.to_simple().to_string(), expected);
    }

    #[test]
    fn test_as_bytes() {
        let u = test_util::new();
        let ub = u.as_bytes();

        assert_eq!(ub.len(), 16);
        assert!(!ub.iter().all(|&b| b == 0));
    }

    #[test]
    fn test_bytes_roundtrip() {
        let b_in: crate::Bytes = [
            0xa1, 0xa2, 0xa3, 0xa4, 0xb1, 0xb2, 0xc1, 0xc2, 0xd1, 0xd2, 0xd3,
            0xd4, 0xd5, 0xd6, 0xd7, 0xd8,
        ];

        let u = Uuid::from_slice(&b_in).unwrap();

        let b_out = u.as_bytes();

        assert_eq!(&b_in, b_out);
    }

    #[test]
    fn test_iterbytes_impl_for_uuid() {
        let mut set = std::collections::HashSet::new();
        let id1 = test_util::new();
        let id2 = test_util::new2();
        set.insert(id1.clone());

        assert!(set.contains(&id1));
        assert!(!set.contains(&id2));
    }
}