tests(iroh): Feature-flag the doc test (#2983)

## Description

This test can only work if the feature is enabled.  Feature-flag the
entire test contents.

Closes #2950.

## Breaking Changes

<!-- Optional, if there are any breaking changes document them,
including how to migrate older code. -->

## Notes & open questions

<!-- Any notes, remarks or open questions you have to make about the PR.
-->

## Change checklist

- [x] Self-review.
- [x] Documentation updates following the [style
guide](https://rust-lang.github.io/rfcs/1574-more-api-documentation-conventions.html#appendix-a-full-conventions-text),
if relevant.
- [x] Tests if relevant.
- [x] All breaking changes documented.

.github/workflows/ci.yml

@@ -216,6 +216,7 @@ jobs:
     env:
       RUSTC_WRAPPER: "sccache"
       SCCACHE_GHA_ENABLED: "on"
+      RUSTDOCFLAGS: --cfg docsrs
     steps:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@master
@@ -226,8 +227,9 @@ jobs:
 
       - name: Docs
         run: cargo doc --workspace --all-features --no-deps --document-private-items
-        env:
-          RUSTDOCFLAGS: --cfg docsrs
+
+      - name: Docs (default features)
+        run: cargo doc --workspace --no-deps
 
   clippy_check:
     timeout-minutes: 30

.github/workflows/tests.yaml

@@ -127,14 +127,25 @@ jobs:
 
       - name: doctests
         if: ${{ (! inputs.flaky) &&  matrix.features == 'all' }}
+        env:
+          RUST_LOG: ${{ runner.debug && 'TRACE' || 'DEBUG'}}
         run: |
-          if [ -n "${{ runner.debug }}" ]; then
-              export RUST_LOG=TRACE
-          else
-              export RUST_LOG=DEBUG
-          fi
           cargo test --workspace --all-features --doc
 
+      # We can not check the doctest features by only compiling them,
+      # so are forced to run them once more.
+      - name: Check doctest features
+        if: ${{ ! inputs.flaky }}
+        env:
+          RUST_LOG: ${{ runner.debug && 'TRACE' || 'DEBUG'}}
+        run: |
+          for i in ${CRATES_LIST//,/ }
+          do
+            echo "Checking $i doctest $FEATURES"
+            echo cargo test -p $i --doc $FEATURES
+            cargo test -p $i --doc $FEATURES
+          done
+
   build_and_test_windows:
     timeout-minutes: 30
     name: "Tests"

iroh-relay/src/server.rs

@@ -138,8 +138,8 @@ pub struct QuicConfig {
     pub bind_addr: SocketAddr,
     /// The TLS server configuration for the QUIC server.
     ///
-    /// If this [`rustls::ServerConfig`] does not support
-    /// TLS 1.3, the QUIC server will fail at [`QuicServer::spawn`].
+    /// If this [`rustls::ServerConfig`] does not support TLS 1.3, the QUIC server will fail
+    /// to spawn.
     pub server_config: rustls::ServerConfig,
 }
 

iroh/src/discovery.rs

@@ -30,9 +30,11 @@
 //!
 //! - The [`PkarrResolver`] which can perform lookups from designated [pkarr relay servers]
 //!   using HTTP.
-//!
-//! - The [`LocalSwarmDiscovery`] discovers iroh nodes present on the local network,
-//!   very similar to mdNS.
+#![cfg_attr(
+    feature = "discovery-local-network",
+    doc = "- [`LocalSwarmDiscovery`]: local_swarm_discovery::LocalSwarmDiscovery
+             very similar to mDNS."
+)]
 //!
 //! - The [`DhtDiscovery`] also uses the [`pkarr`] system but can also publish and lookup
 //!   records to/from the Mainline DHT.
@@ -67,10 +69,18 @@
 //! # }
 //! ```
 //!
-//! To also enable [`LocalSwarmDiscovery`], it can be added as another service in the
+//! To also enable
+#![cfg_attr(feature = "discovery-local-network", doc = "[`LocalSwarmDiscovery`]")]
+#![cfg_attr(
+    not(feature = "discovery-local-network"),
+    doc = "`LocalSwarmDiscovery`"
+)]
+//! it can be added as another service in the
 //! [`ConcurrentDiscovery`]:
 //!
 //! ```no_run
+//! # #[cfg(feature = "discovery-local-network")]
+//! # {
 //! # use iroh::discovery::dns::DnsDiscovery;
 //! # use iroh::discovery::local_swarm_discovery::LocalSwarmDiscovery;
 //! # use iroh::discovery::pkarr::PkarrPublisher;
@@ -86,6 +96,7 @@
 //! ]);
 //! # Ok(())
 //! # }
+//! # }
 //! ```
 //!
 //! [`RelayUrl`]: crate::relay::RelayUrl
@@ -94,9 +105,12 @@
 //! [Number 0]: https://n0.computer
 //! [`PkarrResolver`]: pkarr::PkarrResolver
 //! [`PkarrPublisher`]: pkarr::PkarrPublisher
-//! [`LocalSwarmDiscovery`]: local_swarm_discovery::LocalSwarmDiscovery
 //! [`DhtDiscovery`]: pkarr::dht::DhtDiscovery
 //! [pkarr relay servers]: https://pkarr.org/#servers
+#![cfg_attr(
+    feature = "discovery-local-network",
+    doc = "[`LocalSwarmDiscovery`]: local_swarm_discovery::LocalSwarmDiscovery"
+)]
 
 use std::time::Duration;