Move Uri to its own module

1 files changed, 1610 insertions, 0 deletions

diff --git a/src/uri.rs b/src/uri.rs
new file mode 100644
index 0000000..1c6b364
--- /dev/null
+++ b/src/uri.rs
@@ -0,0 +1,1610 @@
+#![warn(clippy::pedantic)]
+#![allow(clippy::missing_errors_doc)]
+#![allow(clippy::non_ascii_literal)]
+
+use std::collections::HashSet;
+
+use super::authority::Authority;
+use super::codec::{decode_element, encode_element};
+use super::context::Context;
+use super::error::Error;
+use super::character_classes::{
+    ALPHA,
+    SCHEME_NOT_FIRST,
+    PCHAR_NOT_PCT_ENCODED,
+    QUERY_OR_FRAGMENT_NOT_PCT_ENCODED,
+    QUERY_NOT_PCT_ENCODED_WITHOUT_PLUS,
+};
+
+#[derive(Clone, Debug, Default, PartialEq)]
+pub struct Uri {
+    scheme: Option<String>,
+    authority: Option<Authority>,
+    path: Vec<Vec<u8>>,
+    query: Option<Vec<u8>>,
+    fragment: Option<Vec<u8>>,
+}
+
+impl Uri {
+    #[must_use = "respect mah authoritah"]
+    pub fn authority(&self) -> Option<&Authority> {
+        self.authority.as_ref()
+    }
+
+    fn check_scheme<T>(scheme: T) -> Result<T, Error>
+        where T: AsRef<str>
+    {
+        match scheme.as_ref() {
+            "" => return Err(Error::EmptyScheme),
+            scheme => scheme
+                .chars()
+                .enumerate()
+                .try_fold((), |_, (i, c)| {
+                    let valid_characters: &HashSet<char> = if i == 0 {
+                        &ALPHA
+                    } else {
+                        &SCHEME_NOT_FIRST
+                    };
+                    if valid_characters.contains(&c) {
+                        Ok(())
+                    } else {
+                        Err(Error::IllegalCharacter(Context::Scheme))
+                    }
+                })?,
+        };
+        Ok(scheme)
+    }
+
+    #[must_use = "please use the return value kthxbye"]
+    pub fn contains_relative_path(&self) -> bool {
+        !Self::is_path_absolute(&self.path)
+    }
+
+    fn can_navigate_path_up_one_level<T>(path: T) -> bool
+        where T: AsRef<[Vec<u8>]>
+    {
+        let path = path.as_ref();
+        match path.first() {
+            // First segment empty means path has leading slash,
+            // so we can only navigate up if there are two or more segments.
+            Some(segment) if segment.is_empty() => path.len() > 1,
+
+            // Otherwise, we can navigate up as long as there is at least one
+            // segment.
+            Some(_) => true,
+            None => false
+        }
+    }
+
+    fn decode_query_or_fragment<T>(
+        query_or_fragment: T,
+        context: Context,
+    ) -> Result<Vec<u8>, Error>
+        where T: AsRef<str>
+    {
+        decode_element(
+            query_or_fragment,
+            &QUERY_OR_FRAGMENT_NOT_PCT_ENCODED,
+            context
+        )
+    }
+
+    #[must_use = "A query and a fragment walked into a bar.  Too bad you're ignoring the fragment because it's actually a funny joke."]
+    pub fn fragment(&self) -> Option<&[u8]> {
+        self.fragment.as_deref()
+    }
+
+    #[must_use = "use the fragment return value silly programmer"]
+    pub fn fragment_as_string(&self) -> Result<Option<String>, Error> {
+        self.fragment()
+            .map(|fragment| {
+                String::from_utf8(fragment.to_vec())
+                    .map_err(Into::into)
+            })
+            .transpose()
+    }
+
+    #[must_use = "why u no use host return value?"]
+    pub fn host(&self) -> Option<&[u8]> {
+        self.authority
+            .as_ref()
+            .map(Authority::host)
+    }
+
+    #[must_use = "I made that host field into a string for you; don't you want it?"]
+    pub fn host_as_string(&self) -> Result<Option<String>, Error> {
+        self.host()
+            .map(|host| {
+                String::from_utf8(host.to_vec())
+                    .map_err(Into::into)
+            })
+            .transpose()
+    }
+
+    fn is_path_absolute<T>(path: T) -> bool
+        where T: AsRef<[Vec<u8>]>
+    {
+        match path.as_ref() {
+            [segment, ..] if segment.is_empty() => true,
+            _ => false
+        }
+    }
+
+    #[must_use = "why would you call an accessor method and not use the return value, silly human"]
+    pub fn is_relative_reference(&self) -> bool {
+        self.scheme.is_none()
+    }
+
+    pub fn normalize(&mut self) {
+        self.path = Self::normalize_path(&self.path);
+    }
+
+    // This method applies the "remove_dot_segments" routine talked about
+    // in RFC 3986 (https://tools.ietf.org/html/rfc3986) to the path
+    // segments of the URI, in order to normalize the path
+    // (apply and remove "." and ".." segments).
+    fn normalize_path<T>(original_path: T) -> Vec<Vec<u8>>
+        where T: AsRef<[Vec<u8>]>
+    {
+        // Rebuild the path one segment
+        // at a time, removing and applying special
+        // navigation segments ("." and "..") as we go.
+        //
+        // The `at_directory_level` variable tracks whether or not
+        // the `normalized_path` refers to a directory.
+        let mut at_directory_level = false;
+        let mut normalized_path = Vec::new();
+        for segment in original_path.as_ref() {
+            if segment == b"." {
+                at_directory_level = true;
+            } else if segment == b".." {
+                // Remove last path element
+                // if we can navigate up a level.
+                if
+                    !normalized_path.is_empty()
+                    && Self::can_navigate_path_up_one_level(&normalized_path)
+                {
+                    normalized_path.pop();
+                }
+                at_directory_level = true;
+            } else {
+                // Non-relative elements can just
+                // transfer over fine.  An empty
+                // segment marks a transition to
+                // a directory level context.  If we're
+                // already in that context, we
+                // want to ignore the transition.
+                let new_at_directory_level = segment.is_empty();
+                if !at_directory_level || !segment.is_empty() {
+                    normalized_path.push(segment.clone());
+                }
+                at_directory_level = new_at_directory_level;
+            }
+        }
+
+        // If at the end of rebuilding the path,
+        // we're in a directory level context,
+        // add an empty segment to mark the fact.
+        match (at_directory_level, normalized_path.last()) {
+            (true, Some(segment)) if !segment.is_empty() => {
+                normalized_path.push(vec![]);
+            },
+            _ => ()
+        }
+        normalized_path
+    }
+
+    pub fn parse<T>(uri_string: T) -> Result<Self, Error>
+        where T: AsRef<str>
+    {
+        let (scheme, rest) = Self::parse_scheme(uri_string.as_ref())?;
+        let path_end = rest
+            .find(&['?', '#'][..])
+            .unwrap_or_else(|| rest.len());
+        let authority_and_path_string = &rest[0..path_end];
+        let query_and_or_fragment = &rest[path_end..];
+        let (authority, path) = Self::split_authority_from_path_and_parse_them(authority_and_path_string)?;
+        let (fragment, possible_query) = Self::parse_fragment(query_and_or_fragment)?;
+        let query = Self::parse_query(possible_query)?;
+        Ok(Self{
+            scheme,
+            authority,
+            path,
+            query,
+            fragment
+        })
+    }
+
+    fn parse_fragment(query_and_or_fragment: &str) -> Result<(Option<Vec<u8>>, &str), Error> {
+        if let Some(fragment_delimiter) = query_and_or_fragment.find('#') {
+            let fragment = Self::decode_query_or_fragment(
+                &query_and_or_fragment[fragment_delimiter+1..],
+                Context::Fragment
+            )?;
+            Ok((
+                Some(fragment),
+                &query_and_or_fragment[0..fragment_delimiter]
+            ))
+        } else {
+            Ok((
+                None,
+                query_and_or_fragment
+            ))
+        }
+    }
+
+    fn parse_path<T>(path_string: T) -> Result<Vec<Vec<u8>>, Error>
+        where T: AsRef<str>
+    {
+        match path_string.as_ref() {
+            "/" => {
+                // Special case of an empty absolute path, which we want to
+                // represent as single empty-string element to indicate that it
+                // is absolute.
+                Ok(vec![vec![]])
+            },
+
+            "" => {
+                // Special case of an empty relative path, which we want to
+                // represent as an empty vector.
+                Ok(vec![])
+            },
+
+            path_string => {
+                path_string
+                    .split('/')
+                    .map(|segment| {
+                        decode_element(
+                            &segment,
+                            &PCHAR_NOT_PCT_ENCODED,
+                            Context::Path
+                        )
+                    })
+                    .collect()
+            }
+        }
+    }
+
+    fn parse_query<T>(query_and_or_fragment: T) -> Result<Option<Vec<u8>>, Error>
+        where T: AsRef<str>
+    {
+        let query_and_or_fragment = query_and_or_fragment.as_ref();
+        if query_and_or_fragment.is_empty() {
+            Ok(None)
+        } else {
+            let query = Self::decode_query_or_fragment(
+                &query_and_or_fragment[1..],
+                Context::Query
+            )?;
+            Ok(Some(query))
+        }
+    }
+
+    fn parse_scheme(uri_string: &str) -> Result<(Option<String>, &str), Error> {
+        // Limit our search so we don't scan into the authority
+        // or path elements, because these may have the colon
+        // character as well, which we might misinterpret
+        // as the scheme delimiter.
+        let authority_or_path_delimiter_start = uri_string.find('/')
+            .unwrap_or_else(|| uri_string.len());
+        if let Some(scheme_end) = &uri_string[0..authority_or_path_delimiter_start].find(':') {
+            let scheme = Self::check_scheme(&uri_string[0..*scheme_end])?
+                .to_lowercase();
+            Ok((Some(scheme), &uri_string[*scheme_end+1..]))
+        } else {
+            Ok((None, uri_string))
+        }
+    }
+
+    #[must_use = "you called path() to get the path, so why you no use?"]
+    pub fn path(&self) -> &Vec<Vec<u8>> {
+        &self.path
+    }
+
+    #[must_use = "we went through all that trouble to put the path into a string, and you don't want it?"]
+    pub fn path_as_string(&self) -> Result<String, Error> {
+        match &*self.path {
+            [segment] if segment.is_empty() => Ok("/".to_string()),
+            path => Ok(
+                String::from_utf8(
+                    path
+                        .join(&b"/"[..])
+                )?
+            ),
+        }
+    }
+
+    #[must_use = "why did you get the port number and then throw it away?"]
+    pub fn port(&self) -> Option<u16> {
+        if let Some(authority) = &self.authority {
+            authority.port()
+        } else {
+            None
+        }
+    }
+
+    #[must_use = "don't you want to know what that query was?"]
+    pub fn query(&self) -> Option<&[u8]> {
+        self.query.as_deref()
+    }
+
+    #[must_use = "use the query return value silly programmer"]
+    pub fn query_as_string(&self) -> Result<Option<String>, Error> {
+        self.query()
+            .map(|query| {
+                String::from_utf8(query.to_vec())
+                    .map_err(Into::into)
+            })
+            .transpose()
+    }
+
+    #[must_use = "why go through all that effort to resolve the URI, when you're not going to use it?!"]
+    pub fn resolve(&self, relative_reference: &Self) -> Self {
+        // Resolve the reference by following the algorithm
+        // from section 5.2.2 in
+        // RFC 3986 (https://tools.ietf.org/html/rfc3986).
+        let (scheme, authority, path, query) = if relative_reference.scheme.is_some() {
+            (
+                relative_reference.scheme.clone(),
+                relative_reference.authority.clone(),
+                Self::normalize_path(&relative_reference.path),
+                relative_reference.query.clone()
+            )
+        } else {
+            let scheme = self.scheme.clone();
+            if let Some(authority) = &relative_reference.authority {
+                (
+                    scheme,
+                    Some(authority.clone()),
+                    Self::normalize_path(&relative_reference.path),
+                    relative_reference.query.clone()
+                )
+            } else {
+                let authority = self.authority.clone();
+                if relative_reference.path.is_empty() {
+                    let path = self.path.clone();
+                    let query = if relative_reference.query.is_none() {
+                        self.query.clone()
+                    } else {
+                        relative_reference.query.clone()
+                    };
+                    (
+                        scheme,
+                        authority,
+                        path,
+                        query
+                    )
+                } else {
+                    let query = relative_reference.query.clone();
+
+                    // RFC describes this as:
+                    // "if (R.path starts-with "/") then"
+                    if Self::is_path_absolute(&relative_reference.path) {
+                        (
+                            scheme,
+                            authority,
+                            relative_reference.path.clone(),
+                            query
+                        )
+                    } else {
+                        // RFC describes this as:
+                        // "T.path = merge(Base.path, R.path);"
+                        let mut path = self.path.clone();
+                        if path.len() > 1 {
+                            path.pop();
+                        }
+                        path.extend(relative_reference.path.iter().cloned());
+                        (
+                            scheme,
+                            authority,
+                            Self::normalize_path(&path),
+                            query
+                        )
+                    }
+                }
+            }
+        };
+        Self{
+            scheme,
+            authority,
+            path,
+            query,
+            fragment: relative_reference.fragment.clone()
+        }
+    }
+
+    #[must_use = "you wanted to use that scheme, right?"]
+    pub fn scheme(&self) -> Option<&str> {
+        // NOTE: This seemingly magic `as_deref` works because of two
+        // things that are going on here:
+        // 1) String implements DeRef with `str` as the associated type
+        //    `Target`, meaning you can use a String in a context requiring
+        //    &str, and String does the conversion work.
+        // 2) as_deref works by turning `Option<T>` into `Option<&T::Target>`,
+        //    requiring T to implement Deref.  In this case T is String.
+        self.scheme.as_deref()
+    }
+
+    pub fn set_authority<T>(&mut self, authority: T)
+        where T: Into<Option<Authority>>
+    {
+        self.authority = authority.into();
+    }
+
+    pub fn set_fragment<T>(&mut self, fragment: T)
+        where T: Into<Option<Vec<u8>>>
+    {
+        self.fragment = fragment.into();
+    }
+
+    pub fn set_path<T>(&mut self, path: T)
+        where T: Into<Vec<Vec<u8>>>
+    {
+        self.path = path.into();
+    }
+
+    pub fn set_path_from_str<T>(&mut self, path: T)
+        where T: AsRef<str>
+    {
+        match path.as_ref() {
+            "" => self.set_path(vec![]),
+            path => self.set_path(
+                path
+                    .split('/')
+                    .map(|segment| segment.as_bytes().to_vec())
+                    .collect::<Vec<Vec<u8>>>()
+            ),
+        }
+    }
+
+    pub fn set_query<T>(&mut self, query: T)
+        where T: Into<Option<Vec<u8>>>
+    {
+        self.query = query.into();
+    }
+
+    pub fn set_scheme<T>(&mut self, scheme: T) -> Result<(), Error>
+        where T: Into<Option<String>>
+    {
+        self.scheme = match scheme.into() {
+            Some(scheme) => {
+                Self::check_scheme(&scheme)?;
+                Some(scheme)
+            }
+            None => None,
+        };
+        Ok(())
+    }
+
+    fn split_authority_from_path_and_parse_them<T>(
+        authority_and_path_string: T
+    ) -> Result<(Option<Authority>, Vec<Vec<u8>>), Error>
+        where T: AsRef<str>
+    {
+        // Split authority from path.  If there is an authority, parse it.
+        let authority_and_path_string = authority_and_path_string.as_ref();
+        if authority_and_path_string.starts_with("//") {
+            // Strip off authority marker.
+            let authority_and_path_string = &authority_and_path_string[2..];
+
+            // First separate the authority from the path.
+            let authority_end = authority_and_path_string.find('/')
+                .unwrap_or_else(|| authority_and_path_string.len());
+            let authority_string = &authority_and_path_string[0..authority_end];
+            let path_string = &authority_and_path_string[authority_end..];
+
+            // Parse the elements inside the authority string.
+            let authority = Authority::parse(authority_string)?;
+            let path = if path_string.is_empty() {
+                vec![vec![]]
+            } else {
+                Self::parse_path(path_string)?
+            };
+            Ok((Some(authority), path))
+        } else {
+            let path = Self::parse_path(authority_and_path_string)?;
+            Ok((None, path))
+        }
+    }
+
+    #[must_use = "security breach... security breach... userinfo not used"]
+    pub fn userinfo(&self) -> Option<&[u8]> {
+        if let Some(authority) = &self.authority {
+            authority.userinfo()
+        } else {
+            None
+        }
+    }
+
+    #[must_use = "come on, you intended to use that userinfo return value, didn't you?"]
+    pub fn userinfo_as_string(&self) -> Result<Option<String>, Error> {
+        self.userinfo()
+            .map(|userinfo| {
+                String::from_utf8(userinfo.to_vec())
+                    .map_err(Into::into)
+            })
+            .transpose()
+    }
+}
+
+impl std::fmt::Display for Uri {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        if let Some(scheme) = &self.scheme {
+            write!(f, "{}:", scheme)?;
+        }
+        if let Some(authority) = &self.authority {
+            write!(f, "//{}", authority)?;
+        }
+        // Special case: absolute but otherwise empty path.
+        if
+            Self::is_path_absolute(&self.path)
+            && self.path.len() == 1
+        {
+            write!(f, "/")?;
+        }
+        for (i, segment) in self.path.iter().enumerate() {
+            write!(f, "{}", encode_element(segment, &PCHAR_NOT_PCT_ENCODED))?;
+            if i + 1 < self.path.len() {
+                write!(f, "/")?;
+            }
+        }
+        if let Some(query) = &self.query {
+            write!(f, "?{}", encode_element(query, &QUERY_NOT_PCT_ENCODED_WITHOUT_PLUS))?;
+        }
+        if let Some(fragment) = &self.fragment {
+            write!(f, "#{}", encode_element(fragment, &QUERY_OR_FRAGMENT_NOT_PCT_ENCODED))?;
+        }
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+
+    use super::*;
+
+    #[test]
+    fn parse_from_string_no_scheme() {
+        let uri = Uri::parse("foo/bar");
+        assert!(uri.is_ok());
+        let uri = uri.unwrap();
+        assert_eq!(None, uri.scheme());
+        assert_eq!(&[&b"foo"[..], &b"bar"[..]].to_vec(), uri.path());
+        assert_eq!("foo/bar", uri.path_as_string().unwrap());
+    }
+
+    #[test]
+    fn parse_from_string_url() {
+        let uri = Uri::parse("http://www.example.com/foo/bar");
+        assert!(uri.is_ok());
+        let uri = uri.unwrap();
+        assert_eq!(Some("http"), uri.scheme());
+        assert_eq!(Some(&b"www.example.com"[..]), uri.host());
+        assert_eq!(Some("www.example.com"), uri.host_as_string().unwrap().as_deref());
+        assert_eq!(uri.path_as_string().unwrap(), "/foo/bar");
+    }
+
+    #[test]
+    fn parse_from_string_urn_default_path_delimiter() {
+        let uri = Uri::parse("urn:book:fantasy:Hobbit");
+        assert!(uri.is_ok());
+        let uri = uri.unwrap();
+        assert_eq!(Some("urn"), uri.scheme());
+        assert_eq!(None, uri.host());
+        assert_eq!(uri.path_as_string().unwrap(), "book:fantasy:Hobbit");
+    }
+
+    #[test]
+    fn parse_from_string_path_corner_cases() {
+        named_tuple!(
+            struct TestVector {
+                path_in: &'static str,
+                path_out: Vec<&'static [u8]>,
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            ("", vec![]).into(),
+            ("/", vec![&b""[..]]).into(),
+            ("/foo", vec![&b""[..], &b"foo"[..]]).into(),
+            ("foo/", vec![&b"foo"[..], &b""[..]]).into(),
+        ];
+        for test_vector in test_vectors {
+            let uri = Uri::parse(test_vector.path_in());
+            assert!(uri.is_ok());
+            let uri = uri.unwrap();
+            assert_eq!(test_vector.path_out(), uri.path());
+        }
+    }
+
+    #[test]
+    fn parse_from_string_has_a_non_empty_port_number() {
+        let uri = Uri::parse("http://www.example.com:8080/foo/bar");
+        assert!(uri.is_ok());
+        let uri = uri.unwrap();
+        assert_eq!(Some("www.example.com"), uri.host_as_string().unwrap().as_deref());
+        assert_eq!(Some(8080), uri.port());
+    }
+
+    #[test]
+    fn parse_from_string_has_an_empty_port_number() {
+        let uri = Uri::parse("http://www.example.com:/foo/bar");
+        assert!(uri.is_ok());
+        let uri = uri.unwrap();
+        assert_eq!(Some("www.example.com"), uri.host_as_string().unwrap().as_deref());
+        assert_eq!(None, uri.port());
+    }
+
+    #[test]
+    fn parse_from_string_does_not_have_a_port_number() {
+        let uri = Uri::parse("http://www.example.com/foo/bar");
+        assert!(uri.is_ok());
+        let uri = uri.unwrap();
+        assert_eq!(Some("www.example.com"), uri.host_as_string().unwrap().as_deref());
+        assert_eq!(None, uri.port());
+    }
+
+    #[test]
+    fn parse_from_string_twice_first_with_port_number_then_without() {
+        let uri = Uri::parse("http://www.example.com:8080/foo/bar");
+        assert!(uri.is_ok());
+        let uri = Uri::parse("http://www.example.com/foo/bar");
+        assert!(uri.is_ok());
+        let uri = uri.unwrap();
+        assert_eq!(None, uri.port());
+    }
+
+    #[test]
+    fn parse_from_string_bad_port_number_purly_alphabetic() {
+        let uri = Uri::parse("http://www.example.com:spam/foo/bar");
+        assert!(uri.is_err());
+    }
+
+    #[test]
+    fn parse_from_string_bad_port_number_starts_numeric_ends_alphabetic() {
+        let uri = Uri::parse("http://www.example.com:8080spam/foo/bar");
+        assert!(uri.is_err());
+    }
+
+    #[test]
+    fn parse_from_string_largest_valid_port_number() {
+        let uri = Uri::parse("http://www.example.com:65535/foo/bar");
+        assert!(uri.is_ok());
+        let uri = uri.unwrap();
+        assert_eq!(Some(65535), uri.port());
+    }
+
+    #[test]
+    fn parse_from_string_bad_port_number_too_big() {
+        let uri = Uri::parse("http://www.example.com:65536/foo/bar");
+        assert!(matches!(uri, Err(Error::IllegalPortNumber(_))));
+    }
+
+    #[test]
+    fn parse_from_string_bad_port_number_negative() {
+        let uri = Uri::parse("http://www.example.com:-1234/foo/bar");
+        assert!(uri.is_err());
+    }
+
+    #[test]
+    fn parse_from_string_ends_after_authority() {
+        let uri = Uri::parse("http://www.example.com");
+        assert!(uri.is_ok());
+    }
+
+    #[test]
+    fn parse_from_string_relative_vs_non_relative_references() {
+        named_tuple!(
+            struct TestVector {
+                uri_string: &'static str,
+                is_relative_reference: bool
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            ("http://www.example.com/", false).into(),
+            ("http://www.example.com", false).into(),
+            ("/", true).into(),
+            ("foo", true).into(),
+        ];
+        for test_vector in test_vectors {
+            let uri = Uri::parse(test_vector.uri_string());
+            assert!(uri.is_ok());
+            let uri = uri.unwrap();
+            assert_eq!(
+                *test_vector.is_relative_reference(),
+                uri.is_relative_reference()
+            );
+        }
+    }
+
+    #[test]
+    fn parse_from_string_relative_vs_non_relative_paths() {
+        named_tuple!(
+            struct TestVector {
+                uri_string: &'static str,
+                contains_relative_path: bool
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            ("http://www.example.com/", false).into(),
+            ("http://www.example.com", false).into(),
+            ("/", false).into(),
+            ("foo", true).into(),
+
+            // This is only a valid test vector if we understand
+            // correctly that an empty string IS a valid
+            // "relative reference" URI with an empty path.
+            ("", true).into(),
+        ];
+        for (test_index, test_vector) in test_vectors.iter().enumerate() {
+            let uri = Uri::parse(test_vector.uri_string());
+            assert!(uri.is_ok());
+            let uri = uri.unwrap();
+            assert_eq!(
+                *test_vector.contains_relative_path(),
+                uri.contains_relative_path(),
+                "{}", test_index
+            );
+        }
+    }
+
+    #[test]
+    fn parse_from_string_query_and_fragment_elements() {
+        named_tuple!(
+            struct TestVector {
+                uri_string: &'static str,
+                host: &'static str,
+                query: Option<&'static str>,
+                fragment: Option<&'static str>
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            ("http://www.example.com/", "www.example.com", None, None).into(),
+            ("http://example.com?foo", "example.com", Some("foo"), None).into(),
+            ("http://www.example.com#foo", "www.example.com", None, Some("foo")).into(),
+            ("http://www.example.com?foo#bar", "www.example.com", Some("foo"), Some("bar")).into(),
+            ("http://www.example.com?earth?day#bar", "www.example.com", Some("earth?day"), Some("bar")).into(),
+            ("http://www.example.com/spam?foo#bar", "www.example.com", Some("foo"), Some("bar")).into(),
+            ("http://www.example.com/?", "www.example.com", Some(""), None).into(),
+        ];
+        for (test_index, test_vector) in test_vectors.iter().enumerate() {
+            let uri = Uri::parse(test_vector.uri_string());
+            assert!(uri.is_ok());
+            let uri = uri.unwrap();
+            assert_eq!(Some(*test_vector.host()), uri.host_as_string().unwrap().as_deref());
+            assert_eq!(
+                *test_vector.query(),
+                uri.query_as_string().unwrap().as_deref(),
+                "{}", test_index
+            );
+            assert_eq!(
+                *test_vector.fragment(),
+                uri.fragment_as_string().unwrap().as_deref()
+            );
+        }
+    }
+
+    #[test]
+    fn parse_from_string_user_info() {
+        named_tuple!(
+            struct TestVector {
+                uri_string: &'static str,
+                userinfo: Option<&'static str>,
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            ("http://www.example.com/", None).into(),
+            ("http://joe@www.example.com", Some("joe")).into(),
+            ("http://pepe:feelsbadman@www.example.com", Some("pepe:feelsbadman")).into(),
+            ("//www.example.com", None).into(),
+            ("//bob@www.example.com", Some("bob")).into(),
+            ("/", None).into(),
+            ("foo", None).into(),
+        ];
+        for test_vector in test_vectors {
+            let uri = Uri::parse(test_vector.uri_string());
+            assert!(uri.is_ok());
+            let uri = uri.unwrap();
+            assert_eq!(
+                *test_vector.userinfo(),
+                uri.userinfo_as_string().unwrap().as_deref()
+            );
+        }
+    }
+
+    #[test]
+    fn parse_from_string_twice_first_user_info_then_without() {
+        let uri = Uri::parse("http://joe@www.example.com/foo/bar");
+        assert!(uri.is_ok());
+        let uri = Uri::parse("/foo/bar");
+        assert!(uri.is_ok());
+        let uri = uri.unwrap();
+        assert_eq!(None, uri.userinfo());
+    }
+
+    #[test]
+    fn parse_from_string_scheme_illegal_characters() {
+        let test_vectors = [
+            "://www.example.com/",
+            "0://www.example.com/",
+            "+://www.example.com/",
+            "@://www.example.com/",
+            ".://www.example.com/",
+            "h@://www.example.com/",
+        ];
+        for test_vector in &test_vectors {
+            let uri = Uri::parse(*test_vector);
+            assert!(uri.is_err());
+        }
+    }
+
+    #[test]
+    fn parse_from_string_scheme_barely_legal() {
+        named_tuple!(
+            struct TestVector {
+                uri_string: &'static str,
+                scheme: &'static str
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            ("h://www.example.com/", "h").into(),
+            ("x+://www.example.com/", "x+").into(),
+            ("y-://www.example.com/", "y-").into(),
+            ("z.://www.example.com/", "z.").into(),
+            ("aa://www.example.com/", "aa").into(),
+            ("a0://www.example.com/", "a0").into(),
+        ];
+        for test_vector in test_vectors {
+            let uri = Uri::parse(test_vector.uri_string());
+            assert!(uri.is_ok());
+            let uri = uri.unwrap();
+            assert_eq!(Some(*test_vector.scheme()), uri.scheme());
+        }
+    }
+
+    #[test]
+    fn parse_from_string_scheme_mixed_case () {
+        let test_vectors = [
+            "http://www.example.com/",
+            "hTtp://www.example.com/",
+            "HTTP://www.example.com/",
+            "Http://www.example.com/",
+            "HttP://www.example.com/",
+        ];
+        for test_vector in &test_vectors {
+            let uri = Uri::parse(test_vector);
+            assert!(uri.is_ok());
+            let uri = uri.unwrap();
+            assert_eq!(Some("http"), uri.scheme());
+        }
+    }
+
+    #[test]
+    fn parse_from_string_user_info_illegal_characters() {
+        let test_vectors = [
+            "//%X@www.example.com/",
+            "//{@www.example.com/",
+        ];
+        for test_vector in &test_vectors {
+            let uri = Uri::parse(test_vector);
+            assert!(uri.is_err());
+        }
+    }
+
+    #[test]
+    fn parse_from_string_user_info_barely_legal() {
+        named_tuple!(
+            struct TestVector {
+                uri_string: &'static str,
+                userinfo: &'static str
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            ("//%41@www.example.com/", "A").into(),
+            ("//@www.example.com/", "").into(),
+            ("//!@www.example.com/", "!").into(),
+            ("//'@www.example.com/", "'").into(),
+            ("//(@www.example.com/", "(").into(),
+            ("//;@www.example.com/", ";").into(),
+            ("http://:@www.example.com/", ":").into(),
+        ];
+        for test_vector in test_vectors {
+            let uri = Uri::parse(test_vector.uri_string());
+            assert!(uri.is_ok());
+            let uri = uri.unwrap();
+            assert_eq!(
+                Some(*test_vector.userinfo()),
+                uri.userinfo_as_string().unwrap().as_deref()
+            );
+        }
+    }
+
+    #[test]
+    fn parse_from_string_host_illegal_characters() {
+        let test_vectors = [
+            "//%X@www.example.com/",
+            "//@www:example.com/",
+            "//[vX.:]/",
+        ];
+        for test_vector in &test_vectors {
+            let uri = Uri::parse(test_vector);
+            assert!(uri.is_err());
+        }
+    }
+
+    #[test]
+    fn parse_from_string_host_barely_legal() {
+        named_tuple!(
+            struct TestVector {
+                uri_string: &'static str,
+                host: &'static str
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            ("//%41/", "a").into(),
+            ("///", "").into(),
+            ("//!/", "!").into(),
+            ("//'/", "'").into(),
+            ("//(/", "(").into(),
+            ("//;/", ";").into(),
+            ("//1.2.3.4/", "1.2.3.4").into(),
+            ("//[v7.:]/", "v7.:").into(),
+            ("//[v7.aB]/", "v7.aB").into(),
+        ];
+        for test_vector in test_vectors {
+            let uri = Uri::parse(test_vector.uri_string());
+            assert!(uri.is_ok());
+            let uri = uri.unwrap();
+            assert_eq!(Some(*test_vector.host()), uri.host_as_string().unwrap().as_deref());
+        }
+    }
+
+    #[test]
+    fn parse_from_string_host_mixed_case() {
+        let test_vectors = [
+            "http://www.example.com/",
+            "http://www.EXAMPLE.com/",
+            "http://www.exAMple.com/",
+            "http://www.example.cOM/",
+            "http://wWw.exampLe.Com/",
+        ];
+        let normalized_host = "www.example.com";
+        for test_vector in &test_vectors {
+            let uri = Uri::parse(*test_vector);
+            assert!(uri.is_ok());
+            let uri = uri.unwrap();
+            assert_eq!(
+                Some(normalized_host),
+                uri.host_as_string().unwrap().as_deref()
+            );
+        }
+    }
+
+    #[test]
+    fn parse_from_string_host_ends_in_dot() {
+        let uri = Uri::parse("http://example.com./foo");
+        assert!(uri.is_ok());
+        let uri = uri.unwrap();
+        assert_eq!(Some("example.com."), uri.host_as_string().unwrap().as_deref());
+    }
+
+    #[test]
+    fn parse_from_string_dont_misinterpret_colon_in_other_places_as_scheme_delimiter() {
+        let test_vectors = [
+            "//foo:bar@www.example.com/",
+            "//www.example.com/a:b",
+            "//www.example.com/foo?a:b",
+            "//www.example.com/foo#a:b",
+            "//[v7.:]/",
+            "/:/foo",
+        ];
+        for test_vector in &test_vectors {
+            let uri = Uri::parse(test_vector);
+            assert!(uri.is_ok());
+            let uri = uri.unwrap();
+            assert_eq!(None, uri.scheme());
+        }
+    }
+
+    #[test]
+    fn parse_from_string_path_illegal_characters() {
+        let test_vectors = [
+            "http://www.example.com/foo[bar",
+            "http://www.example.com/]bar",
+            "http://www.example.com/foo]",
+            "http://www.example.com/[",
+            "http://www.example.com/abc/foo]",
+            "http://www.example.com/abc/[",
+            "http://www.example.com/foo]/abc",
+            "http://www.example.com/[/abc",
+            "http://www.example.com/foo]/",
+            "http://www.example.com/[/",
+            "/foo[bar",
+            "/]bar",
+            "/foo]",
+            "/[",
+            "/abc/foo]",
+            "/abc/[",
+            "/foo]/abc",
+            "/[/abc",
+            "/foo]/",
+            "/[/",
+        ];
+        for test_vector in &test_vectors {
+            let uri = Uri::parse(test_vector);
+            assert!(uri.is_err());
+        }
+    }
+
+    #[test]
+    fn parse_from_string_path_barely_legal() {
+        named_tuple!(
+            struct TestVector {
+                uri_string: &'static str,
+                path: Vec<&'static [u8]>
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            ("/:/foo", vec![&b""[..], &b":"[..], &b"foo"[..]]).into(),
+            ("bob@/foo", vec![&b"bob@"[..], &b"foo"[..]]).into(),
+            ("hello!", vec![&b"hello!"[..]]).into(),
+            ("urn:hello,%20w%6Frld", vec![&b"hello, world"[..]]).into(),
+            ("//example.com/foo/(bar)/", vec![&b""[..], &b"foo"[..], &b"(bar)"[..], &b""[..]]).into(),
+        ];
+        for test_vector in test_vectors {
+            let uri = Uri::parse(test_vector.uri_string());
+            assert!(uri.is_ok());
+            let uri = uri.unwrap();
+            assert_eq!(test_vector.path(), uri.path());
+        }
+    }
+
+    #[test]
+    fn parse_from_string_query_illegal_characters() {
+        let test_vectors = [
+            "http://www.example.com/?foo[bar",
+            "http://www.example.com/?]bar",
+            "http://www.example.com/?foo]",
+            "http://www.example.com/?[",
+            "http://www.example.com/?abc/foo]",
+            "http://www.example.com/?abc/[",
+            "http://www.example.com/?foo]/abc",
+            "http://www.example.com/?[/abc",
+            "http://www.example.com/?foo]/",
+            "http://www.example.com/?[/",
+            "?foo[bar",
+            "?]bar",
+            "?foo]",
+            "?[",
+            "?abc/foo]",
+            "?abc/[",
+            "?foo]/abc",
+            "?[/abc",
+            "?foo]/",
+            "?[/",
+        ];
+        for test_vector in &test_vectors {
+            let uri = Uri::parse(test_vector);
+            assert!(uri.is_err());
+        }
+    }
+
+    #[test]
+    fn parse_from_string_query_barely_legal() {
+        named_tuple!(
+            struct TestVector {
+                uri_string: &'static str,
+                query: &'static str
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            ("/?:/foo", ":/foo").into(),
+            ("?bob@/foo", "bob@/foo").into(),
+            ("?hello!", "hello!").into(),
+            ("urn:?hello,%20w%6Frld", "hello, world").into(),
+            ("//example.com/foo?(bar)/", "(bar)/").into(),
+            ("http://www.example.com/?foo?bar", "foo?bar").into(),
+        ];
+        for (test_index, test_vector) in test_vectors.iter().enumerate() {
+            let uri = Uri::parse(test_vector.uri_string());
+            assert!(uri.is_ok());
+            let uri = uri.unwrap();
+            assert_eq!(
+                Some(*test_vector.query()),
+                uri.query_as_string().unwrap().as_deref(),
+                "{}", test_index
+            );
+        }
+    }
+
+    #[test]
+    fn parse_from_string_fragment_illegal_characters() {
+        let test_vectors = [
+            "http://www.example.com/#foo[bar",
+            "http://www.example.com/#]bar",
+            "http://www.example.com/#foo]",
+            "http://www.example.com/#[",
+            "http://www.example.com/#abc/foo]",
+            "http://www.example.com/#abc/[",
+            "http://www.example.com/#foo]/abc",
+            "http://www.example.com/#[/abc",
+            "http://www.example.com/#foo]/",
+            "http://www.example.com/#[/",
+            "#foo[bar",
+            "#]bar",
+            "#foo]",
+            "#[",
+            "#abc/foo]",
+            "#abc/[",
+            "#foo]/abc",
+            "#[/abc",
+            "#foo]/",
+            "#[/",
+        ];
+        for test_vector in &test_vectors {
+            let uri = Uri::parse(test_vector);
+            assert!(uri.is_err());
+        }
+    }
+
+    #[test]
+    fn parse_from_string_fragment_barely_legal() {
+        named_tuple!(
+            struct TestVector {
+                uri_string: &'static str,
+                fragment: &'static str
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            ("/#:/foo", ":/foo").into(),
+            ("#bob@/foo", "bob@/foo").into(),
+            ("#hello!", "hello!").into(),
+            ("urn:#hello,%20w%6Frld", "hello, world").into(),
+            ("//example.com/foo#(bar)/", "(bar)/").into(),
+            ("http://www.example.com/#foo?bar", "foo?bar").into(),
+        ];
+        for test_vector in test_vectors {
+            let uri = Uri::parse(test_vector.uri_string());
+            assert!(uri.is_ok());
+            let uri = uri.unwrap();
+            assert_eq!(
+                Some(*test_vector.fragment()),
+                uri.fragment_as_string().unwrap().as_deref()
+            );
+        }
+    }
+
+    #[test]
+    fn parse_from_string_paths_with_percent_encoded_characters() {
+        named_tuple!(
+            struct TestVector {
+                uri_string: &'static str,
+                path_first_segment: &'static [u8]
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            ("%41", &b"A"[..]).into(),
+            ("%4A", &b"J"[..]).into(),
+            ("%4a", &b"J"[..]).into(),
+            ("%bc", &b"\xBC"[..]).into(),
+            ("%Bc", &b"\xBC"[..]).into(),
+            ("%bC", &b"\xBC"[..]).into(),
+            ("%BC", &b"\xBC"[..]).into(),
+            ("%41%42%43", &b"ABC"[..]).into(),
+            ("%41%4A%43%4b", &b"AJCK"[..]).into(),
+        ];
+        for test_vector in test_vectors {
+            let uri = Uri::parse(test_vector.uri_string());
+            assert!(uri.is_ok());
+            let uri = uri.unwrap();
+            assert_eq!(
+                test_vector.path_first_segment(),
+                uri.path().first().unwrap()
+            );
+        }
+    }
+
+    #[test]
+    fn normalize_path() {
+        named_tuple!(
+            struct TestVector {
+                uri_string: &'static str,
+                normalized_path: &'static str,
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            ("/a/b/c/./../../g", "/a/g").into(),
+            ("mid/content=5/../6", "mid/6").into(),
+            ("http://example.com/a/../b", "/b").into(),
+            ("http://example.com/../b", "/b").into(),
+            ("http://example.com/a/../b/", "/b/").into(),
+            ("http://example.com/a/../../b", "/b").into(),
+            ("./a/b", "a/b").into(),
+            ("", "").into(),
+            (".", "").into(),
+            ("./", "").into(),
+            ("..", "").into(),
+            ("../", "").into(),
+            ("/", "/").into(),
+            ("a/b/..", "a/").into(),
+            ("a/b/../", "a/").into(),
+            ("a/b/.", "a/b/").into(),
+            ("a/b/./", "a/b/").into(),
+            ("a/b/./c", "a/b/c").into(),
+            ("a/b/./c/", "a/b/c/").into(),
+            ("/a/b/..", "/a/").into(),
+            ("/a/b/.", "/a/b/").into(),
+            ("/a/b/./c", "/a/b/c").into(),
+            ("/a/b/./c/", "/a/b/c/").into(),
+            ("./a/b/..", "a/").into(),
+            ("./a/b/.", "a/b/").into(),
+            ("./a/b/./c", "a/b/c").into(),
+            ("./a/b/./c/", "a/b/c/").into(),
+            ("../a/b/..", "a/").into(),
+            ("../a/b/.", "a/b/").into(),
+            ("../a/b/./c", "a/b/c").into(),
+            ("../a/b/./c/", "a/b/c/").into(),
+            ("../a/b/../c", "a/c").into(),
+            ("../a/b/./../c/", "a/c/").into(),
+            ("../a/b/./../c", "a/c").into(),
+            ("../a/b/./../c/", "a/c/").into(),
+            ("../a/b/.././c/", "a/c/").into(),
+            ("../a/b/.././c", "a/c").into(),
+            ("../a/b/.././c/", "a/c/").into(),
+            ("/./c/d", "/c/d").into(),
+            ("/../c/d", "/c/d").into(),
+        ];
+        for test_vector in test_vectors.iter() {
+            let uri = Uri::parse(test_vector.uri_string());
+            assert!(uri.is_ok());
+            let mut uri = uri.unwrap();
+            uri.normalize();
+            assert_eq!(
+                *test_vector.normalized_path(),
+                uri.path_as_string().unwrap(),
+                "{}", test_vector.uri_string()
+            );
+        }
+    }
+
+    #[test]
+    fn construct_normalize_and_compare_equivalent_uris() {
+        // This was inspired by section 6.2.2
+        // of RFC 3986 (https://tools.ietf.org/html/rfc3986).
+        let uri1 = Uri::parse("example://a/b/c/%7Bfoo%7D");
+        assert!(uri1.is_ok());
+        let uri1 = uri1.unwrap();
+        let uri2 = Uri::parse("eXAMPLE://a/./b/../b/%63/%7bfoo%7d");
+        assert!(uri2.is_ok());
+        let mut uri2 = uri2.unwrap();
+        assert_ne!(uri1, uri2);
+        uri2.normalize();
+        assert_eq!(uri1, uri2);
+    }
+
+    #[test]
+    fn reference_resolution() {
+        named_tuple!(
+            struct TestVector {
+                base_string: &'static str,
+                relative_reference_string: &'static str,
+                target_string: &'static str
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            // These are all taken from section 5.4.1
+            // of RFC 3986 (https://tools.ietf.org/html/rfc3986).
+            ("http://a/b/c/d;p?q", "g:h", "g:h").into(),
+            ("http://a/b/c/d;p?q", "g", "http://a/b/c/g").into(),
+            ("http://a/b/c/d;p?q", "./g", "http://a/b/c/g").into(),
+            ("http://a/b/c/d;p?q", "g/", "http://a/b/c/g/").into(),
+            ("http://a/b/c/d;p?q", "//g", "http://g").into(),
+            ("http://a/b/c/d;p?q", "?y", "http://a/b/c/d;p?y").into(),
+            ("http://a/b/c/d;p?q", "g?y", "http://a/b/c/g?y").into(),
+            ("http://a/b/c/d;p?q", "#s", "http://a/b/c/d;p?q#s").into(),
+            ("http://a/b/c/d;p?q", "g#s", "http://a/b/c/g#s").into(),
+            ("http://a/b/c/d;p?q", "g?y#s", "http://a/b/c/g?y#s").into(),
+            ("http://a/b/c/d;p?q", ";x", "http://a/b/c/;x").into(),
+            ("http://a/b/c/d;p?q", "g;x", "http://a/b/c/g;x").into(),
+            ("http://a/b/c/d;p?q", "g;x?y#s", "http://a/b/c/g;x?y#s").into(),
+            ("http://a/b/c/d;p?q", "", "http://a/b/c/d;p?q").into(),
+            ("http://a/b/c/d;p?q", ".", "http://a/b/c/").into(),
+            ("http://a/b/c/d;p?q", "./", "http://a/b/c/").into(),
+            ("http://a/b/c/d;p?q", "..", "http://a/b/").into(),
+            ("http://a/b/c/d;p?q", "../", "http://a/b/").into(),
+            ("http://a/b/c/d;p?q", "../g", "http://a/b/g").into(),
+            ("http://a/b/c/d;p?q", "../..", "http://a").into(),
+            ("http://a/b/c/d;p?q", "../../", "http://a").into(),
+            ("http://a/b/c/d;p?q", "../../g", "http://a/g").into(),
+
+            // Here are some examples of our own.
+            ("http://example.com", "foo", "http://example.com/foo").into(),
+            ("http://example.com/", "foo", "http://example.com/foo").into(),
+            ("http://example.com", "foo/", "http://example.com/foo/").into(),
+            ("http://example.com/", "foo/", "http://example.com/foo/").into(),
+            ("http://example.com", "/foo", "http://example.com/foo").into(),
+            ("http://example.com/", "/foo", "http://example.com/foo").into(),
+            ("http://example.com", "/foo/", "http://example.com/foo/").into(),
+            ("http://example.com/", "/foo/", "http://example.com/foo/").into(),
+            ("http://example.com/", "?foo", "http://example.com/?foo").into(),
+            ("http://example.com/", "#foo", "http://example.com/#foo").into(),
+        ];
+        for test_vector in test_vectors {
+            let base_uri = Uri::parse(test_vector.base_string()).unwrap();
+            let relative_reference_uri = Uri::parse(test_vector.relative_reference_string()).unwrap();
+            let expected_target_uri = Uri::parse(test_vector.target_string()).unwrap();
+            let actual_target_uri = base_uri.resolve(&relative_reference_uri);
+            assert_eq!(expected_target_uri, actual_target_uri);
+        }
+    }
+
+    #[test]
+    fn empty_path_in_uri_with_authority_is_equivalent_to_slash_only_path() {
+        let uri1 = Uri::parse("http://example.com");
+        assert!(uri1.is_ok());
+        let uri1 = uri1.unwrap();
+        let uri2 = Uri::parse("http://example.com/");
+        assert!(uri2.is_ok());
+        let uri2 = uri2.unwrap();
+        assert_eq!(uri1, uri2);
+        let uri1 = Uri::parse("//example.com");
+        assert!(uri1.is_ok());
+        let uri1 = uri1.unwrap();
+        let uri2 = Uri::parse("//example.com/");
+        assert!(uri2.is_ok());
+        let uri2 = uri2.unwrap();
+        assert_eq!(uri1, uri2);
+    }
+
+    #[test]
+    fn ipv6_address_good() {
+        named_tuple!(
+            struct TestVector {
+                uri_string: &'static str,
+                expected_host: &'static str,
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            ("http://[::1]/", "::1").into(),
+            ("http://[::ffff:1.2.3.4]/", "::ffff:1.2.3.4").into(),
+            ("http://[2001:db8:85a3:8d3:1319:8a2e:370:7348]/", "2001:db8:85a3:8d3:1319:8a2e:370:7348").into(),
+            ("http://[2001:db8:85a3:8d3:1319:8a2e:370::]/", "2001:db8:85a3:8d3:1319:8a2e:370::").into(),
+            ("http://[2001:db8:85a3:8d3:1319:8a2e::1]/", "2001:db8:85a3:8d3:1319:8a2e::1").into(),
+            ("http://[fFfF::1]", "fFfF::1").into(),
+            ("http://[1234::1]", "1234::1").into(),
+            ("http://[fFfF:1:2:3:4:5:6:a]", "fFfF:1:2:3:4:5:6:a").into(),
+            ("http://[2001:db8:85a3::8a2e:0]/", "2001:db8:85a3::8a2e:0").into(),
+            ("http://[2001:db8:85a3:8a2e::]/", "2001:db8:85a3:8a2e::").into(),
+        ];
+        for test_vector in test_vectors {
+            let uri = Uri::parse(test_vector.uri_string());
+            assert!(uri.is_ok());
+            assert_eq!(
+                Some(*test_vector.expected_host()),
+                uri.unwrap().host_as_string().unwrap().as_deref()
+            );
+        }
+    }
+
+    #[test]
+    fn ipv6_address_bad() {
+        named_tuple!(
+            struct TestVector {
+                uri_string: &'static str,
+                expected_error: Error,
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            ("http://[::fFfF::1]", Error::TooManyDoubleColons).into(),
+            ("http://[::ffff:1.2.x.4]/", Error::IllegalCharacter(Context::Ipv4Address)).into(),
+            ("http://[::ffff:1.2.3.4.8]/", Error::TooManyAddressParts).into(),
+            ("http://[::ffff:1.2.3]/", Error::TooFewAddressParts).into(),
+            ("http://[::ffff:1.2.3.]/", Error::TruncatedHost).into(),
+            ("http://[::ffff:1.2.3.256]/", Error::InvalidDecimalOctet).into(),
+            ("http://[::fxff:1.2.3.4]/", Error::IllegalCharacter(Context::Ipv6Address)).into(),
+            ("http://[::ffff:1.2.3.-4]/", Error::IllegalCharacter(Context::Ipv4Address)).into(),
+            ("http://[::ffff:1.2.3. 4]/", Error::IllegalCharacter(Context::Ipv4Address)).into(),
+            ("http://[::ffff:1.2.3.4 ]/", Error::IllegalCharacter(Context::Ipv4Address)).into(),
+            ("http://[::ffff:1.2.3.4/", Error::TruncatedHost).into(),
+            ("http://[2001:db8:85a3:8d3:1319:8a2e:370:7348:0000]/", Error::TooManyAddressParts).into(),
+            ("http://[2001:db8:85a3:8d3:1319:8a2e:370:7348::1]/", Error::TooManyAddressParts).into(),
+            ("http://[2001:db8:85a3:8d3:1319:8a2e:370::1]/", Error::TooManyAddressParts).into(),
+            ("http://[2001:db8:85a3::8a2e:0:]/", Error::TruncatedHost).into(),
+            ("http://[2001:db8:85a3::8a2e::]/", Error::TooManyDoubleColons).into(),
+            ("http://[]/", Error::TooFewAddressParts).into(),
+            ("http://[:]/", Error::TruncatedHost).into(),
+            ("http://[v]/", Error::TruncatedHost).into(),
+        ];
+        for test_vector in test_vectors {
+            let uri = Uri::parse(test_vector.uri_string());
+            assert_eq!(
+                *test_vector.expected_error(),
+                uri.unwrap_err(),
+                "{}",
+                test_vector.uri_string()
+            );
+        }
+
+        // This is a special case because std::num doesn't trust that we're
+        // good enough to make our own ParseIntError values.  FeelsBadMan
+        let uri = Uri::parse("http://::ffff:1.2.3.4]/");
+        assert!(matches!(uri, Err(Error::IllegalPortNumber(_))));
+    }
+
+    #[test]
+    // NOTE: `clippy::too_many_arguments` lint has to be disabled at the
+    // test level because it's triggered inside the `named_tuple!` macro
+    // expansion.
+    #[allow(clippy::too_many_arguments)]
+    fn generate_string() {
+        named_tuple!(
+            struct TestVector {
+                scheme: Option<&'static str>,
+                userinfo: Option<&'static str>,
+                host: Option<&'static str>,
+                port: Option<u16>,
+                path: &'static str,
+                query: Option<&'static str>,
+                fragment: Option<&'static str>,
+                expected_uri_string: &'static str
+            }
+        );
+        let test_vectors: &[TestVector] = &[
+            // general test vectors
+            // scheme      userinfo     host                     port        path         query           fragment     expected_uri_string
+            (Some("http"), Some("bob"), Some("www.example.com"), Some(8080), "/abc/def",  Some("foobar"), Some("ch2"), "http://bob@www.example.com:8080/abc/def?foobar#ch2").into(),
+            (Some("http"), Some("bob"), Some("www.example.com"), Some(0),    "",          Some("foobar"), Some("ch2"), "http://bob@www.example.com:0?foobar#ch2").into(),
+            (Some("http"), Some("bob"), Some("www.example.com"), Some(0),    "",          Some("foobar"), Some(""),    "http://bob@www.example.com:0?foobar#").into(),
+            (None,         None,        Some("example.com"),     None,       "",          Some("bar"),    None,        "//example.com?bar").into(),
+            (None,         None,        Some("example.com"),     None,       "",          Some(""),       None,        "//example.com?").into(),
+            (None,         None,        Some("example.com"),     None,       "",          None,           None,        "//example.com").into(),
+            (None,         None,        Some("example.com"),     None,       "/",         None,           None,        "//example.com/").into(),
+            (None,         None,        Some("example.com"),     None,       "/xyz",      None,           None,        "//example.com/xyz").into(),
+            (None,         None,        Some("example.com"),     None,       "/xyz/",     None,           None,        "//example.com/xyz/").into(),
+            (None,         None,        None,                    None,       "/",         None,           None,        "/").into(),
+            (None,         None,        None,                    None,       "/xyz",      None,           None,        "/xyz").into(),
+            (None,         None,        None,                    None,       "/xyz/",     None,           None,        "/xyz/").into(),
+            (None,         None,        None,                    None,       "",          None,           None,        "").into(),
+            (None,         None,        None,                    None,       "xyz",       None,           None,        "xyz").into(),
+            (None,         None,        None,                    None,       "xyz/",      None,           None,        "xyz/").into(),
+            (None,         None,        None,                    None,       "",          Some("bar"),    None,        "?bar").into(),
+            (Some("http"), None,        None,                    None,       "",          Some("bar"),    None,        "http:?bar").into(),
+            (Some("http"), None,        None,                    None,       "",          None,           None,        "http:").into(),
+            (Some("http"), None,        Some("::1"),             None,       "",          None,           None,        "http://[::1]").into(),
+            (Some("http"), None,        Some("::1.2.3.4"),       None,       "",          None,           None,        "http://[::1.2.3.4]").into(),
+            (Some("http"), None,        Some("1.2.3.4"),         None,       "",          None,           None,        "http://1.2.3.4").into(),
+            (None,         None,        None,                    None,       "",          None,           None,        "").into(),
+            (Some("http"), Some("bob"), None,                    None,       "",          Some("foobar"), None,        "http://bob@?foobar").into(),
+            (None,         Some("bob"), None,                    None,       "",          Some("foobar"), None,        "//bob@?foobar").into(),
+            (None,         Some("bob"), None,                    None,       "",          None,           None,        "//bob@").into(),
+
+            // percent-encoded character test vectors
+            // scheme      userinfo      host                     port        path        query            fragment     expected_uri_string
+            (Some("http"), Some("b b"),  Some("www.example.com"), Some(8080), "/abc/def", Some("foobar"),  Some("ch2"), "http://b%20b@www.example.com:8080/abc/def?foobar#ch2").into(),
+            (Some("http"), Some("bob"),  Some("www.e ample.com"), Some(8080), "/abc/def", Some("foobar"),  Some("ch2"), "http://bob@www.e%20ample.com:8080/abc/def?foobar#ch2").into(),
+            (Some("http"), Some("bob"),  Some("www.example.com"), Some(8080), "/a c/def", Some("foobar"),  Some("ch2"), "http://bob@www.example.com:8080/a%20c/def?foobar#ch2").into(),
+            (Some("http"), Some("bob"),  Some("www.example.com"), Some(8080), "/abc/def", Some("foo ar"),  Some("ch2"), "http://bob@www.example.com:8080/abc/def?foo%20ar#ch2").into(),
+            (Some("http"), Some("bob"),  Some("www.example.com"), Some(8080), "/abc/def", Some("foobar"),  Some("c 2"), "http://bob@www.example.com:8080/abc/def?foobar#c%202").into(),
+            (Some("http"), Some("bob"),  Some("ሴ.example.com"),   Some(8080), "/abc/def", Some("foobar"),  None,        "http://bob@%E1%88%B4.example.com:8080/abc/def?foobar").into(),
+
+            // normalization of IPv6 address hex digits
+            // scheme      userinfo     host                   port        path        query           fragment     expected_uri_string
+            (Some("http"), Some("bob"), Some("fFfF::1"),       Some(8080), "/abc/def", Some("foobar"), Some("c 2"), "http://bob@[ffff::1]:8080/abc/def?foobar#c%202").into(),
+        ];
+        for test_vector in test_vectors {
+            let mut uri = Uri::default();
+            assert!(uri.set_scheme(test_vector.scheme().map(ToString::to_string)).is_ok());
+            if
+                test_vector.userinfo().is_some()
+                || test_vector.host().is_some()
+                || test_vector.port().is_some()
+            {
+                let mut authority = Authority::default();
+                authority.set_userinfo(test_vector.userinfo().map(Into::into));
+                authority.set_host(test_vector.host().unwrap_or_else(|| ""));
+                authority.set_port(*test_vector.port());
+                uri.set_authority(Some(authority));
+            } else {
+                uri.set_authority(None);
+            }
+            uri.set_path_from_str(test_vector.path());
+            uri.set_query(test_vector.query().map(Into::into));
+            uri.set_fragment(test_vector.fragment().map(Into::into));
+            assert_eq!(
+                *test_vector.expected_uri_string(),
+                uri.to_string()
+            );
+        }
+    }
+
+    #[test]
+    fn fragment_empty_but_present() {
+        let uri = Uri::parse("http://example.com#");
+        assert!(uri.is_ok());
+        let mut uri = uri.unwrap();
+        assert_eq!(Some(&b""[..]), uri.fragment());
+        assert_eq!(uri.to_string(), "http://example.com/#");
+        uri.set_fragment(None);
+        assert_eq!(uri.to_string(), "http://example.com/");
+        assert_eq!(None, uri.fragment());
+
+        let uri = Uri::parse("http://example.com");
+        assert!(uri.is_ok());
+        let mut uri = uri.unwrap();
+        assert_eq!(None, uri.fragment());
+        uri.set_fragment(Some(vec![]));
+        assert_eq!(Some(&b""[..]), uri.fragment());
+        assert_eq!(uri.to_string(), "http://example.com/#");
+    }
+
+    #[test]
+    fn query_empty_but_present() {
+        let uri = Uri::parse("http://example.com?");
+        assert!(uri.is_ok());
+        let mut uri = uri.unwrap();
+        assert_eq!(Some(&b""[..]), uri.query());
+        assert_eq!(uri.to_string(), "http://example.com/?");
+        uri.set_query(None);
+        assert_eq!(uri.to_string(), "http://example.com/");
+        assert_eq!(None, uri.query());
+
+        let uri = Uri::parse("http://example.com");
+        assert!(uri.is_ok());
+        let mut uri = uri.unwrap();
+        assert_eq!(None, uri.query());
+        uri.set_query(Some(vec![]));
+        assert_eq!(Some(&b""[..]), uri.query());
+        assert_eq!(uri.to_string(), "http://example.com/?");
+    }
+
+    #[test]
+    fn make_a_copy() {
+        let mut uri1 = Uri::parse("http://www.example.com/foo.txt").unwrap();
+        let mut uri2 = uri1.clone();
+        uri1.set_query(Some(b"bar".to_vec()));
+        uri2.set_fragment(Some(b"page2".to_vec()));
+        let mut uri2_new_auth = uri2.authority().unwrap().clone();
+        uri2_new_auth.set_host("example.com");
+        uri2.set_authority(Some(uri2_new_auth));
+        assert_eq!(uri1.to_string(), "http://www.example.com/foo.txt?bar");
+        assert_eq!(uri2.to_string(), "http://example.com/foo.txt#page2");
+    }
+
+    #[test]
+    fn clear_query() {
+        let mut uri = Uri::parse("http://www.example.com/?foo=bar").unwrap();
+        uri.set_query(None);
+        assert_eq!(uri.to_string(), "http://www.example.com/");
+        assert_eq!(None, uri.query());
+    }
+
+    #[test]
+    fn percent_encode_plus_in_queries() {
+        // Although RFC 3986 doesn't say anything about '+', some web services
+        // treat it the same as ' ' due to how HTML originally defined how
+        // to encode the query portion of a URL
+        // (see https://stackoverflow.com/questions/2678551/when-to-encode-space-to-plus-or-20).
+        //
+        // To avoid issues with these web services, make sure '+' is
+        // percent-encoded in a URI when the URI is encoded.
+        let mut uri = Uri::default();
+        uri.set_query(Some(b"foo+bar".to_vec()));
+        assert_eq!(uri.to_string(), "?foo%2Bbar");
+    }
+
+    #[test]
+    fn set_illegal_schemes() {
+        let test_vectors = [
+            "ab_de",
+            "ab/de",
+            "ab:de",
+            "",
+            "&",
+            "foo&bar",
+        ];
+        for test_vector in &test_vectors {
+            let mut uri = Uri::default();
+            assert!(uri.set_scheme(Some((*test_vector).to_string())).is_err());
+        }
+    }
+
+}