Precisely route formats. Make 'content_type' an 'Option' in 'Request'.

This commit changes the routing algorithm. In particular, it enforces
precise matching of formats. With this change, a route with a specified
format only matches requests that have the same format specified. A
route with no format specified matches any request's format. This is
contrast to the previous behavior, where a route without a specified
format would match requests regardless of their format or whether one
was specified.

This commit also changes the following:
  * The return type of the 'content_type' method of 'Request' is now
    'Option<ContentType>'.
  * The 'ContentType' request guard forwards when the request has no
    specified ContentType.
  * The 'add_header' and 'replace_header' methods take the header
    argument generically.

Closes #120.

contrib/src/json/mod.rs

@@ -73,7 +73,7 @@ impl<T: Deserialize> FromData for JSON<T> {
     type Error = SerdeError;
 
     fn from_data(request: &Request, data: Data) -> data::Outcome<Self, SerdeError> {
-        if !request.content_type().is_json() {
+        if !request.content_type().map_or(false, |ct| ct.is_json()) {
             error_!("Content-Type is not JSON.");
             return Outcome::Forward(data);
         }

examples/content_types/src/main.rs

@@ -6,8 +6,7 @@ extern crate serde_json;
 #[macro_use]
 extern crate serde_derive;
 
-#[cfg(test)]
+#[cfg(test)] mod tests;
-mod tests;
 
 use rocket::Request;
 use rocket::http::ContentType;
@@ -34,13 +33,13 @@ fn hello(content_type: ContentType, name: String, age: i8) -> content::JSON<Stri
 
 #[error(404)]
 fn not_found(request: &Request) -> content::HTML<String> {
-    let html = if !request.content_type().is_json() {
+    let html = match request.content_type() {
-        format!("<p>This server only supports JSON requests, not '{}'.</p>",
+        Some(ref ct) if !ct.is_json() => {
-                request.content_type())
+            format!("<p>This server only supports JSON requests, not '{}'.</p>", ct)
-    } else {
+        }
-        format!("<p>Sorry, '{}' is an invalid path! Try \
+        _ => format!("<p>Sorry, '{}' is an invalid path! Try \
                  /hello/&lt;name&gt;/&lt;age&gt; instead.</p>",
-                request.uri())
+                 request.uri())
     };
 
     content::HTML(html)

examples/manual_routes/src/main.rs

@@ -28,7 +28,7 @@ fn echo_url(req: &Request, _: Data) -> Outcome<'static> {
 }
 
 fn upload<'r>(req: &'r Request, data: Data) -> Outcome<'r> {
-    if !req.content_type().is_plain() {
+    if !req.content_type().map_or(false, |ct| ct.is_plain()) {
         println!("    => Content-Type of upload must be text/plain. Ignoring.");
         return Outcome::failure(Status::BadRequest);
     }

lib/src/data/from_data.rs

@@ -99,7 +99,7 @@ impl<'a, S, E> IntoOutcome<S, (Status, E), Data> for Result<S, E> {
 ///     fn from_data(req: &Request, data: Data) -> data::Outcome<Self, String> {
 ///         // Ensure the content type is correct before opening the data.
 ///         let person_ct = ContentType::new("application", "x-person");
-///         if req.content_type() != person_ct {
+///         if req.content_type() != Some(person_ct) {
 ///             return Outcome::Forward(data);
 ///         }
 ///

lib/src/http/content_type.rs

@@ -5,7 +5,6 @@ use std::fmt;
 use http::Header;
 use http::hyper::mime::Mime;
 use http::ascii::{uncased_eq, UncasedAscii};
-use router::Collider;
 
 /// Representation of HTTP Content-Types.
 ///
@@ -419,13 +418,6 @@ impl Into<Header<'static>> for ContentType {
     }
 }
 
-impl Collider for ContentType {
-    fn collides_with(&self, other: &ContentType) -> bool {
-        let collide = |a, b| a == "*" || b == "*" || a == b;
-        collide(&self.ttype, &other.ttype) && collide(&self.subtype, &other.subtype)
-    }
-}
-
 #[cfg(test)]
 mod test {
     use super::ContentType;

lib/src/http/uri.rs

@@ -8,8 +8,6 @@ use std::str::Utf8Error;
 
 use url;
 
-use router::Collider;
-
 /// Index (start, end) into a string, to prevent borrowing.
 type Index = (usize, usize);
 
@@ -299,26 +297,6 @@ impl<'a> fmt::Display for URI<'a> {
 
 unsafe impl<'a> Sync for URI<'a> { /* It's safe! */ }
 
-impl<'a, 'b> Collider<URI<'b>> for URI<'a> {
-    fn collides_with(&self, other: &URI<'b>) -> bool {
-        for (seg_a, seg_b) in self.segments().zip(other.segments()) {
-            if seg_a.ends_with("..>") || seg_b.ends_with("..>") {
-                return true;
-            }
-
-            if !seg_a.collides_with(seg_b) {
-                return false;
-            }
-        }
-
-        if self.segment_count() != other.segment_count() {
-            return false;
-        }
-
-        true
-    }
-}
-
 /// Iterator over the segments of an absolute URI path. Skips empty segments.
 ///
 /// ### Examples

lib/src/request/form/mod.rs

@@ -234,7 +234,7 @@ impl<'f, T: FromForm<'f>> FromData for Form<'f, T> where T::Error: Debug {
     type Error = Option<String>;
 
     fn from_data(request: &Request, data: Data) -> data::Outcome<Self, Self::Error> {
-        if !request.content_type().is_form() {
+        if !request.content_type().map_or(false, |ct| ct.is_form()) {
             warn_!("Form data does not have form content type.");
             return Forward(data);
         }

lib/src/request/from_request.rs

@@ -97,10 +97,8 @@ impl<S, E> IntoOutcome<S, (Status, E), ()> for Result<S, E> {
 ///   * **ContentType**
 ///
 ///     Extracts the [ContentType](/rocket/http/struct.ContentType.html) from
-///     the incoming request. If the request didn't specify a Content-Type, a
+///     the incoming request. If the request didn't specify a Content-Type, the
-///     Content-Type of `*/*` (`Any`) is returned.
+///     request is forwarded.
-///
-///     _This implementation always returns successfully._
 ///
 ///   * **SocketAddr**
 ///
@@ -217,7 +215,10 @@ impl<'a, 'r> FromRequest<'a, 'r> for ContentType {
     type Error = ();
 
     fn from_request(request: &'a Request<'r>) -> Outcome<Self, Self::Error> {
-        Success(request.content_type())
+        match request.content_type() {
+            Some(content_type) => Success(content_type),
+            None => Forward(())
+        }
     }
 }
 

lib/src/request/request.rs

@@ -201,13 +201,13 @@ impl<'r> Request<'r> {
     /// let mut request = Request::new(Method::Get, "/uri");
     /// assert!(request.headers().is_empty());
     ///
-    /// request.add_header(ContentType::HTML.into());
+    /// request.add_header(ContentType::HTML);
     /// assert!(request.headers().contains("Content-Type"));
     /// assert_eq!(request.headers().len(), 1);
     /// ```
     #[inline(always)]
-    pub fn add_header(&mut self, header: Header<'r>) {
+    pub fn add_header<H: Into<Header<'r>>>(&mut self, header: H) {
-        self.headers.add(header);
+        self.headers.add(header.into());
     }
 
     /// Replaces the value of the header with `header.name` with `header.value`.
@@ -222,15 +222,15 @@ impl<'r> Request<'r> {
     /// let mut request = Request::new(Method::Get, "/uri");
     /// assert!(request.headers().is_empty());
     ///
-    /// request.add_header(ContentType::HTML.into());
+    /// request.add_header(ContentType::HTML);
-    /// assert_eq!(request.content_type(), ContentType::HTML);
+    /// assert_eq!(request.content_type(), Some(ContentType::HTML));
     ///
-    /// request.replace_header(ContentType::JSON.into());
+    /// request.replace_header(ContentType::JSON);
-    /// assert_eq!(request.content_type(), ContentType::JSON);
+    /// assert_eq!(request.content_type(), Some(ContentType::JSON));
     /// ```
     #[inline(always)]
-    pub fn replace_header(&mut self, header: Header<'r>) {
+    pub fn replace_header<H: Into<Header<'r>>>(&mut self, header: H) {
-        self.headers.replace(header);
+        self.headers.replace(header.into());
     }
 
     /// Returns a borrow to the cookies in `self`.
@@ -262,8 +262,8 @@ impl<'r> Request<'r> {
         self.cookies = cookies;
     }
 
-    /// Returns the Content-Type header of `self`. If the header is not present,
+    /// Returns `Some` of the Content-Type header of `self`. If the header is
-    /// returns `ContentType::Any`.
+    /// not present, returns `None`.
     ///
     /// # Example
     ///
@@ -272,16 +272,15 @@ impl<'r> Request<'r> {
     /// use rocket::http::{Method, ContentType};
     ///
     /// let mut request = Request::new(Method::Get, "/uri");
-    /// assert_eq!(request.content_type(), ContentType::Any);
+    /// assert_eq!(request.content_type(), None);
     ///
-    /// request.replace_header(ContentType::JSON.into());
+    /// request.replace_header(ContentType::JSON);
-    /// assert_eq!(request.content_type(), ContentType::JSON);
+    /// assert_eq!(request.content_type(), Some(ContentType::JSON));
     /// ```
     #[inline(always)]
-    pub fn content_type(&self) -> ContentType {
+    pub fn content_type(&self) -> Option<ContentType> {
         self.headers().get_one("Content-Type")
             .and_then(|value| value.parse().ok())
-            .unwrap_or(ContentType::Any)
     }
 
     /// Retrieves and parses into `T` the 0-indexed `n`th dynamic parameter from
@@ -458,8 +457,10 @@ impl<'r> fmt::Display for Request<'r> {
     /// infrastructure.
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "{} {}", Green.paint(&self.method), Blue.paint(&self.uri))?;
-        if self.method.supports_payload() && !self.content_type().is_any() {
+        if let Some(content_type) = self.content_type() {
-            write!(f, " {}", Yellow.paint(self.content_type()))?;
+            if self.method.supports_payload() {
+                write!(f, " {}", Yellow.paint(content_type))?;
+            }
         }
 
         Ok(())

lib/src/rocket.rs

@@ -161,7 +161,7 @@ impl Rocket {
         // field which we use to reinterpret the request's method.
         let data_len = data.peek().len();
         let (min_len, max_len) = ("_method=get".len(), "_method=delete".len());
-        let is_form = req.content_type().is_form();
+        let is_form = req.content_type().map_or(false, |ct| ct.is_form());
         if is_form && req.method() == Method::Post && data_len >= min_len {
             let form = unsafe {
                 from_utf8_unchecked(&data.peek()[..min(data_len, max_len)])

lib/src/router/collider.rs

@@ -1,3 +1,9 @@
+use super::Route;
+
+use http::uri::URI;
+use http::ContentType;
+use request::Request;
+
 /// The Collider trait is used to determine if two items that can be routed on
 /// can match against a given request. That is, if two items `collide`, they
 /// will both match against _some_ request.
@@ -44,18 +50,80 @@ impl<'a> Collider<str> for &'a str {
     }
 }
 
+impl<'a, 'b> Collider<URI<'b>> for URI<'a> {
+    fn collides_with(&self, other: &URI<'b>) -> bool {
+        for (seg_a, seg_b) in self.segments().zip(other.segments()) {
+            if seg_a.ends_with("..>") || seg_b.ends_with("..>") {
+                return true;
+            }
+
+            if !seg_a.collides_with(seg_b) {
+                return false;
+            }
+        }
+
+        if self.segment_count() != other.segment_count() {
+            return false;
+        }
+
+        true
+    }
+}
+
+impl Collider for ContentType  {
+    fn collides_with(&self, other: &ContentType) -> bool {
+        let collide = |a, b| a == "*" || b == "*" || a == b;
+        collide(&self.ttype, &other.ttype) && collide(&self.subtype, &other.subtype)
+    }
+}
+
+// This implementation is used at initialization to check if two user routes
+// collide before launching. Format collisions works like this:
+//   * If route a specifies format, it only gets requests for that format.
+//   * If a route doesn't specify format, it gets requests for any format.
+impl Collider for Route {
+    fn collides_with(&self, b: &Route) -> bool {
+        self.method == b.method
+            && self.rank == b.rank
+            && self.path.collides_with(&b.path)
+            && match (self.format.as_ref(), b.format.as_ref()) {
+                (Some(ct_a), Some(ct_b)) => ct_a.collides_with(ct_b),
+                (Some(_), None) => true,
+                (None, Some(_)) => true,
+                (None, None) => true
+            }
+    }
+}
+
+// This implementation is used at runtime to check if a given request is
+// intended for this Route. Format collisions works like this:
+//   * If route a specifies format, it only gets requests for that format.
+//   * If a route doesn't specify format, it gets requests for any format.
+impl<'r> Collider<Request<'r>> for Route {
+    fn collides_with(&self, req: &Request<'r>) -> bool {
+        self.method == req.method()
+            && req.uri().collides_with(&self.path)
+            // FIXME: On payload requests, check Content-Type, else Accept.
+            && match (req.content_type().as_ref(), self.format.as_ref()) {
+                (Some(ct_a), Some(ct_b)) => ct_a.collides_with(ct_b),
+                (Some(_), None) => true,
+                (None, Some(_)) => false,
+                (None, None) => true
+            }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use std::str::FromStr;
 
-    use router::Collider;
+    use super::Collider;
     use request::Request;
     use data::Data;
     use handler::Outcome;
     use router::route::Route;
     use http::{Method, ContentType};
     use http::uri::URI;
-
     use http::Method::*;
 
     type SimpleRoute = (Method, &'static str);
@@ -199,12 +267,6 @@ mod tests {
         assert!(!s_s_collide("/a/hi/<a..>", "/a/hi/"));
     }
 
-    fn ct_route(m: Method, s: &str, ct: &str) -> Route {
-        let mut route_a = Route::new(m, s, dummy_handler);
-        route_a.format = ContentType::from_str(ct).expect("Whoops!");
-        route_a
-    }
-
     fn ct_ct_collide(ct1: &str, ct2: &str) -> bool {
         let ct_a = ContentType::from_str(ct1).expect(ct1);
         let ct_b = ContentType::from_str(ct2).expect(ct2);
@@ -229,10 +291,20 @@ mod tests {
         assert!(!ct_ct_collide("something/*", "random/else"));
     }
 
-    fn r_ct_ct_collide(m1: Method, ct1: &str, m2: Method, ct2: &str) -> bool {
+    fn r_ct_ct_collide<S1, S2>(m1: Method, ct1: S1, m2: Method, ct2: S2) -> bool
-        let a_route = ct_route(m1, "a", ct1);
+        where S1: Into<Option<&'static str>>, S2: Into<Option<&'static str>>
-        let b_route = ct_route(m2, "a", ct2);
+    {
-        a_route.collides_with(&b_route)
+        let mut route_a = Route::new(m1, "/", dummy_handler);
+        if let Some(ct_str) = ct1.into() {
+            route_a.format = Some(ct_str.parse::<ContentType>().unwrap());
+        }
+
+        let mut route_b = Route::new(m2, "/", dummy_handler);
+        if let Some(ct_str) = ct2.into() {
+            route_b.format = Some(ct_str.parse::<ContentType>().unwrap());
+        }
+
+        route_a.collides_with(&route_b)
     }
 
     #[test]
@@ -241,9 +313,56 @@ mod tests {
         assert!(r_ct_ct_collide(Get, "*/json", Get, "application/json"));
         assert!(r_ct_ct_collide(Get, "*/json", Get, "application/*"));
         assert!(r_ct_ct_collide(Get, "text/html", Get, "text/*"));
+        assert!(r_ct_ct_collide(Get, "any/thing", Get, "*/*"));
+
+        assert!(r_ct_ct_collide(Get, None, Get, "text/*"));
+        assert!(r_ct_ct_collide(Get, None, Get, "text/html"));
+        assert!(r_ct_ct_collide(Get, None, Get, "*/*"));
+        assert!(r_ct_ct_collide(Get, "text/html", Get, None));
+        assert!(r_ct_ct_collide(Get, "*/*", Get, None));
+        assert!(r_ct_ct_collide(Get, "application/json", Get, None));
 
         assert!(!r_ct_ct_collide(Get, "text/html", Get, "application/*"));
         assert!(!r_ct_ct_collide(Get, "application/html", Get, "text/*"));
         assert!(!r_ct_ct_collide(Get, "*/json", Get, "text/html"));
+        assert!(!r_ct_ct_collide(Get, "text/html", Get, "text/css"));
+    }
+
+    fn req_route_collide<S1, S2>(m1: Method, ct1: S1, m2: Method, ct2: S2) -> bool
+        where S1: Into<Option<&'static str>>, S2: Into<Option<&'static str>>
+    {
+        let mut req = Request::new(m1, "/");
+        if let Some(ct_str) = ct1.into() {
+            req.replace_header(ct_str.parse::<ContentType>().unwrap());
+        }
+
+        let mut route = Route::new(m2, "/", dummy_handler);
+        if let Some(ct_str) = ct2.into() {
+            route.format = Some(ct_str.parse::<ContentType>().unwrap());
+        }
+
+        route.collides_with(&req)
+    }
+
+    #[test]
+    fn test_req_route_ct_collisions() {
+        assert!(req_route_collide(Get, "application/json", Get, "application/json"));
+        assert!(req_route_collide(Get, "application/json", Get, "application/*"));
+        assert!(req_route_collide(Get, "application/json", Get, "*/json"));
+        assert!(req_route_collide(Get, "text/html", Get, "text/html"));
+        assert!(req_route_collide(Get, "text/html", Get, "*/*"));
+
+        assert!(req_route_collide(Get, "text/html", Get, None));
+        assert!(req_route_collide(Get, None, Get, None));
+        assert!(req_route_collide(Get, "application/json", Get, None));
+        assert!(req_route_collide(Get, "x-custom/anything", Get, None));
+
+        assert!(!req_route_collide(Get, "application/json", Get, "text/html"));
+        assert!(!req_route_collide(Get, "application/json", Get, "text/*"));
+        assert!(!req_route_collide(Get, "application/json", Get, "*/xml"));
+
+        assert!(!req_route_collide(Get, None, Get, "text/html"));
+        assert!(!req_route_collide(Get, None, Get, "*/*"));
+        assert!(!req_route_collide(Get, None, Get, "application/json"));
     }
 }

lib/src/router/mod.rs

@@ -1,11 +1,11 @@
 mod collider;
 mod route;
 
-pub use self::collider::Collider;
-pub use self::route::Route;
-
 use std::collections::hash_map::HashMap;
 
+use self::collider::Collider;
+pub use self::route::Route;
+
 use request::Request;
 use http::Method;
 
@@ -206,7 +206,6 @@ mod test {
         assert!(route(&router, Get, "/a/b/").is_some());
         assert!(route(&router, Get, "/i/a").is_some());
         assert!(route(&router, Get, "/a/b/c/d/e/f").is_some());
-
     }
 
     #[test]

lib/src/router/route.rs

@@ -1,14 +1,11 @@
 use std::fmt;
 use std::convert::From;
 
-use super::Collider; // :D
-
 use term_painter::ToStyle;
 use term_painter::Color::*;
 
 use codegen::StaticRouteInfo;
 use handler::Handler;
-use request::Request;
 use http::{Method, ContentType};
 use http::uri::URI;
 
@@ -23,7 +20,7 @@ pub struct Route {
     /// The rank of this route. Lower ranks have higher priorities.
     pub rank: isize,
     /// The Content-Type this route matches against.
-    pub format: ContentType,
+    pub format: Option<ContentType>,
 }
 
 fn default_rank(path: &str) -> isize {
@@ -45,7 +42,7 @@ impl Route {
             handler: handler,
             rank: default_rank(path.as_ref()),
             path: URI::from(path.as_ref().to_string()),
-            format: ContentType::Any,
+            format: None,
         }
     }
 
@@ -58,7 +55,7 @@ impl Route {
             path: URI::from(path.as_ref().to_string()),
             handler: handler,
             rank: rank,
-            format: ContentType::Any,
+            format: None,
         }
     }
 
@@ -115,11 +112,11 @@ impl fmt::Display for Route {
             write!(f, " [{}]", White.paint(&self.rank))?;
         }
 
-        if !self.format.is_any() {
+        if let Some(ref format) = self.format {
-            write!(f, " {}", Yellow.paint(&self.format))
+            write!(f, " {}", Yellow.paint(format))?;
-        } else {
-            Ok(())
         }
+
+        Ok(())
     }
 }
 
@@ -133,7 +130,7 @@ impl fmt::Debug for Route {
 impl<'a> From<&'a StaticRouteInfo> for Route {
     fn from(info: &'a StaticRouteInfo) -> Route {
         let mut route = Route::new(info.method, info.path, info.handler);
-        route.format = info.format.clone().unwrap_or(ContentType::Any);
+        route.format = info.format.clone();
         if let Some(rank) = info.rank {
             route.rank = rank;
         }
@@ -141,22 +138,3 @@ impl<'a> From<&'a StaticRouteInfo> for Route {
         route
     }
 }
-
-impl Collider for Route {
-    fn collides_with(&self, b: &Route) -> bool {
-        self.method == b.method
-            && self.rank == b.rank
-            && self.format.collides_with(&b.format)
-            && self.path.collides_with(&b.path)
-    }
-}
-
-impl<'r> Collider<Request<'r>> for Route {
-    fn collides_with(&self, req: &Request<'r>) -> bool {
-        self.method == req.method()
-            && req.uri().collides_with(&self.path)
-            // FIXME: On payload requests, check Content-Type. On non-payload
-            // requests, check Accept.
-            && req.content_type().collides_with(&self.format)
-    }
-}

lib/src/testing.rs

@@ -140,11 +140,30 @@ impl<'r> MockRequest<'r> {
     /// let req = MockRequest::new(Get, "/").header(ContentType::JSON);
     /// ```
     #[inline]
-    pub fn header<'h, H: Into<Header<'static>>>(mut self, header: H) -> Self {
+    pub fn header<H: Into<Header<'static>>>(mut self, header: H) -> Self {
         self.request.add_header(header.into());
         self
     }
 
+    /// Adds a header to this request without consuming `self`.
+    ///
+    /// # Examples
+    ///
+    /// Add the Content-Type header:
+    ///
+    /// ```rust
+    /// use rocket::http::Method::*;
+    /// use rocket::testing::MockRequest;
+    /// use rocket::http::ContentType;
+    ///
+    /// let mut req = MockRequest::new(Get, "/");
+    /// req.add_header(ContentType::JSON);
+    /// ```
+    #[inline]
+    pub fn add_header<H: Into<Header<'static>>>(&mut self, header: H) {
+        self.request.add_header(header.into());
+    }
+
     /// Set the remote address of this request.
     ///
     /// # Examples
@@ -164,25 +183,6 @@ impl<'r> MockRequest<'r> {
         self
     }
 
-    /// Adds a header to this request. Does not consume `self`.
-    ///
-    /// # Examples
-    ///
-    /// Add the Content-Type header:
-    ///
-    /// ```rust
-    /// use rocket::http::Method::*;
-    /// use rocket::testing::MockRequest;
-    /// use rocket::http::ContentType;
-    ///
-    /// let mut req = MockRequest::new(Get, "/");
-    /// req.add_header(ContentType::JSON);
-    /// ```
-    #[inline]
-    pub fn add_header<'h, H: Into<Header<'static>>>(&mut self, header: H) {
-        self.request.add_header(header.into());
-    }
-
     /// Add a cookie to this request.
     ///
     /// # Examples

lib/tests/precise-content-type-matching.rs

@@ -0,0 +1,74 @@
+#![feature(plugin)]
+#![plugin(rocket_codegen)]
+
+extern crate rocket;
+
+#[post("/", format = "application/json")]
+fn specified() -> &'static str {
+    "specified"
+}
+
+#[post("/", rank = 2)]
+fn unspecified() -> &'static str {
+    "unspecified"
+}
+
+#[post("/", format = "application/json")]
+fn specified_json() -> &'static str {
+    "specified_json"
+}
+
+#[post("/", format = "text/html")]
+fn specified_html() -> &'static str {
+    "specified_html"
+}
+
+#[cfg(feature = "testing")]
+mod tests {
+    use super::*;
+
+    use rocket::Rocket;
+    use rocket::testing::MockRequest;
+    use rocket::http::Method::*;
+    use rocket::http::{Status, ContentType};
+
+    fn rocket() -> Rocket {
+        rocket::ignite()
+            .mount("/first", routes![specified, unspecified])
+            .mount("/second", routes![specified_json, specified_html])
+    }
+
+    macro_rules! check_dispatch {
+        ($mount:expr, $ct:expr, $body:expr) => (
+            let rocket = rocket();
+            let mut req = MockRequest::new(Post, $mount);
+            let ct: Option<ContentType> = $ct;
+            if let Some(ct) = ct {
+                req.add_header(ct);
+            }
+
+            let mut response = req.dispatch_with(&rocket);
+            let body_str = response.body().and_then(|b| b.into_string());
+            let body: Option<&'static str> = $body;
+            match body {
+                Some(string) => assert_eq!(body_str, Some(string.to_string())),
+                None => assert_eq!(response.status(), Status::NotFound)
+            }
+        )
+    }
+
+    #[test]
+    fn exact_match_or_forward() {
+        check_dispatch!("/first", Some(ContentType::JSON), Some("specified"));
+        check_dispatch!("/first", None, Some("unspecified"));
+        check_dispatch!("/first", Some(ContentType::HTML), Some("unspecified"));
+    }
+
+    #[test]
+    fn exact_match_or_none() {
+        check_dispatch!("/second", Some(ContentType::JSON), Some("specified_json"));
+        check_dispatch!("/second", Some(ContentType::HTML), Some("specified_html"));
+        check_dispatch!("/second", Some(ContentType::CSV), None);
+        check_dispatch!("/second", None, None);
+    }
+}