feat(http2): add new error variant for HTTP/2

Automatic conversion from the `solicit::http::HttpError` is also
provided.

BREAKING CHANGE: A new variant `Http2` added to a public enum
`hyper::Error`.

src/error.rs

@@ -6,6 +6,7 @@ use std::io::Error as IoError;
 use httparse;
 use openssl::ssl::error::SslError;
 use url;
+use solicit::http::HttpError as Http2Error;
 
 use self::Error::{
     Method,
@@ -15,7 +16,8 @@ use self::Error::{
     Status,
     Io,
     Ssl,
-    TooLarge
+    TooLarge,
+    Http2,
 };
 
 
@@ -40,7 +42,9 @@ pub enum Error {
     /// An `io::Error` that occurred while trying to read or write to a network stream.
     Io(IoError),
     /// An error from the `openssl` library.
-    Ssl(SslError)
+    Ssl(SslError),
+    /// An HTTP/2-specific error, coming from the `solicit` library.
+    Http2(Http2Error),
 }
 
 impl fmt::Display for Error {
@@ -60,6 +64,7 @@ impl StdError for Error {
             Uri(ref e) => e.description(),
             Io(ref e) => e.description(),
             Ssl(ref e) => e.description(),
+            Http2(ref e) => e.description(),
         }
     }
 
@@ -68,6 +73,7 @@ impl StdError for Error {
             Io(ref error) => Some(error),
             Ssl(ref error) => Some(error),
             Uri(ref error) => Some(error),
+            Http2(ref error) => Some(error),
             _ => None,
         }
     }
@@ -108,12 +114,19 @@ impl From<httparse::Error> for Error {
     }
 }
 
+impl From<Http2Error> for Error {
+    fn from(err: Http2Error) -> Error {
+        Error::Http2(err)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use std::error::Error as StdError;
     use std::io;
     use httparse;
     use openssl::ssl::error::SslError;
+    use solicit::http::HttpError as Http2Error;
     use url;
     use super::Error;
     use super::Error::*;
@@ -156,6 +169,7 @@ mod tests {
         from_and_cause!(io::Error::new(io::ErrorKind::Other, "other") => Io(..));
         from_and_cause!(url::ParseError::EmptyHost => Uri(..));
         from_and_cause!(SslError::SslSessionClosed => Ssl(..));
+        from_and_cause!(Http2Error::UnknownStreamId => Http2(..));
 
         from!(SslError::StreamError(io::Error::new(io::ErrorKind::Other, "ssl negotiation")) => Io(..));