Move tests and support utilities to sub crates. (#268)

These crates will not be published to crates.io, but moving them allows
`tower-h2` to also depend on the test utilities.

tests/h2-support/src/mod.rs

@@ -0,0 +1,69 @@
+//! Utilities to support tests.
+
+#[cfg(not(feature = "unstable"))]
+compile_error!(
+    "Tests depend on the 'unstable' feature on h2. \
+    Retry with `cargo test --features unstable`"
+);
+
+pub extern crate bytes;
+pub extern crate env_logger;
+pub extern crate futures;
+pub extern crate h2;
+pub extern crate http;
+pub extern crate string;
+pub extern crate tokio_io;
+
+// Kind of annoying, but we can't use macros from crates that aren't specified
+// at the root.
+macro_rules! try_ready {
+    ($e:expr) => ({
+        use $crate::support::futures::Async;
+        match $e {
+            Ok(Async::Ready(t)) => t,
+            Ok(Async::NotReady) => return Ok(Async::NotReady),
+            Err(e) => return Err(From::from(e)),
+        }
+    })
+}
+
+macro_rules! try_nb {
+    ($e:expr) => ({
+        use ::std::io::ErrorKind::WouldBlock;
+        use $crate::support::futures::Async;
+
+        match $e {
+            Ok(t) => t,
+            Err(ref e) if e.kind() == WouldBlock => {
+                return Ok(Async::NotReady)
+            }
+            Err(e) => return Err(e.into()),
+        }
+    })
+}
+
+#[macro_use]
+mod assert;
+
+#[macro_use]
+pub mod raw;
+
+pub mod frames;
+pub mod prelude;
+pub mod mock;
+pub mod mock_io;
+pub mod notify;
+pub mod util;
+
+mod future_ext;
+
+pub use self::future_ext::{FutureExt, Unwrap};
+
+pub type WindowSize = usize;
+pub const DEFAULT_WINDOW_SIZE: WindowSize = (1 << 16) - 1;
+
+// This is our test Codec type
+pub type Codec<T> = h2::Codec<T, ::std::io::Cursor<::bytes::Bytes>>;
+
+// This is the frame type that is sent
+pub type SendFrame = h2::frame::Frame<::std::io::Cursor<::bytes::Bytes>>;