ensure that tests work when only server-auto feature is enabled (#271)

These two commands:
cargo test --no-default-features --features server-auto --features tokio
cargo test --no-default-features --features server-auto

Author: alexanderkjall

Cargo.toml

@@ -40,7 +40,7 @@ hyper = { version = "1.4.0", features = ["full"] }
 bytes = "1"
 futures-util = { version = "0.3.16", default-features = false, features = ["alloc"] }
 http-body-util = "0.1.0"
-tokio = { version = "1", features = ["macros", "test-util", "signal"] }
+tokio = { version = "1", features = ["macros", "test-util", "signal", "net"] }
 tokio-test = "0.4"
 tower-test = "0.4"
 pretty_env_logger = "0.5"

src/server/conn/auto/mod.rs

@@ -80,12 +80,15 @@ impl<E> Builder<E> {
     /// # Example
     ///
     /// ```
+    /// # #[cfg(feature = "tokio")]
+    /// # {
     /// use hyper_util::{
     ///     rt::TokioExecutor,
     ///     server::conn::auto,
     /// };
     ///
     /// auto::Builder::new(TokioExecutor::new());
+    /// # }
     /// ```
     pub fn new(executor: E) -> Self {
         Self {
@@ -171,13 +174,16 @@ impl<E> Builder<E> {
     /// # Example
     ///
     /// ```
+    /// # #[cfg(feature = "tokio")]
+    /// # {
     /// use hyper_util::{
     ///     rt::TokioExecutor,
     ///     server::conn::auto,
     /// };
     ///
     /// auto::Builder::new(TokioExecutor::new())
     ///     .title_case_headers(true);
+    /// # }
     /// ```
     #[cfg(feature = "http1")]
     pub fn title_case_headers(mut self, enabled: bool) -> Self {
@@ -195,13 +201,16 @@ impl<E> Builder<E> {
     /// # Example
     ///
     /// ```
+    /// # #[cfg(feature = "tokio")]
+    /// # {
     /// use hyper_util::{
     ///     rt::TokioExecutor,
     ///     server::conn::auto,
     /// };
     ///
     /// auto::Builder::new(TokioExecutor::new())
     ///     .preserve_header_case(true);
+    /// # }
     /// ```
     #[cfg(feature = "http1")]
     pub fn preserve_header_case(mut self, enabled: bool) -> Self {
@@ -1124,7 +1133,7 @@ impl<E> Http2Builder<'_, E> {
     }
 }
 
-#[cfg(test)]
+#[cfg(all(feature = "tokio", test))]
 mod tests {
     use crate::{
         rt::{TokioExecutor, TokioIo},