From bdc82eb6393789b16c69987ab1db0762c7297081 Mon Sep 17 00:00:00 2001
From: Rick Newton-Rogers <rnro@apple.com>
Date: Thu, 6 Mar 2025 09:30:36 +0000
Subject: [PATCH 1/2] Enable strict concurrency checking for NIOTestUtils

Motivation:

To ensure `NIOTestUtils` concurrency safety.

Modifications:

* Enable strict concurrency checking in the package manifest.
* `NIOHTTP1TestServer` does pipeline configuration as synchronous
  operations.

Result:

`NIOTestUtils` does not warn of concurrency issues, builds will warn and CI will fail if regressions are introduced.
---
 Package.swift                                 |  3 ++-
 Sources/NIOTestUtils/NIOHTTP1TestServer.swift | 18 ++++++++----------
 2 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/Package.swift b/Package.swift
index 0a57fa70d12..71b69bd15fa 100644
--- a/Package.swift
+++ b/Package.swift
@@ -233,7 +233,8 @@ let package = Package(
                 "NIOEmbedded",
                 "NIOHTTP1",
                 swiftAtomics,
-            ]
+            ],
+            swiftSettings: strictConcurrencySettings
         ),
         .target(
             name: "_NIOFileSystem",
diff --git a/Sources/NIOTestUtils/NIOHTTP1TestServer.swift b/Sources/NIOTestUtils/NIOHTTP1TestServer.swift
index 6687d6e8838..2a2676cabb7 100644
--- a/Sources/NIOTestUtils/NIOHTTP1TestServer.swift
+++ b/Sources/NIOTestUtils/NIOHTTP1TestServer.swift
@@ -263,18 +263,16 @@ public final class NIOHTTP1TestServer {
             self.handleChannels()
             return
         }
-        channel.pipeline.configureHTTPServerPipeline().flatMap {
+        do {
+            try channel.pipeline.syncOperations.configureHTTPServerPipeline()
             if self.aggregateBody {
-                return channel.pipeline.addHandler(AggregateBodyHandler())
-            } else {
-                return self.eventLoop.makeSucceededVoidFuture()
+                try channel.pipeline.syncOperations.addHandler(AggregateBodyHandler())
             }
-        }.flatMap {
-            channel.pipeline.addHandler(WebServerHandler(webServer: self))
-        }.flatMap {
-            channel.pipeline.addHandler(TransformerHandler())
-        }.whenSuccess {
-            _ = channel.setOption(.autoRead, value: true)
+            try channel.pipeline.syncOperations.addHandler(WebServerHandler(webServer: self))
+            try channel.pipeline.syncOperations.addHandler(TransformerHandler())
+            _ = try channel.syncOptions!.setOption(.autoRead, value: true)
+        } catch {
+            assertionFailure("Channel initialization failed with: \(error)")
         }
     }
 

From ddef4954ca476d4cadf79f2ee6973cc267f6037d Mon Sep 17 00:00:00 2001
From: Rick Newton-Rogers <rnro@apple.com>
Date: Fri, 7 Mar 2025 09:56:56 +0000
Subject: [PATCH 2/2] NIOHTTP1TestServer fatalErrors on channel init failure

---
 Sources/NIOTestUtils/NIOHTTP1TestServer.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Sources/NIOTestUtils/NIOHTTP1TestServer.swift b/Sources/NIOTestUtils/NIOHTTP1TestServer.swift
index 2a2676cabb7..08712e2f95b 100644
--- a/Sources/NIOTestUtils/NIOHTTP1TestServer.swift
+++ b/Sources/NIOTestUtils/NIOHTTP1TestServer.swift
@@ -272,7 +272,7 @@ public final class NIOHTTP1TestServer {
             try channel.pipeline.syncOperations.addHandler(TransformerHandler())
             _ = try channel.syncOptions!.setOption(.autoRead, value: true)
         } catch {
-            assertionFailure("Channel initialization failed with: \(error)")
+            fatalError("Channel initialization failed with: \(error)")
         }
     }