Add more tracing tests (#58)

Motivation:

The OTel tracing interceptors have a few shortcomings
which need fixing. This includes ending the span too
early. This change introduces a number of new tests
which test client and server end-to-end. These tests
currently fail because of the aforementioned issues so
are disabled.

Modifications:

- Add echo service
- Add tracing tests

Result:

Better test coverage

Author: glbrntt

Package.swift

@@ -55,7 +55,7 @@ let dependencies: [Package.Dependency] = [
   ),
   .package(
     url: "https://github.com/apple/swift-distributed-tracing.git",
-    from: "1.1.2"
+    from: "1.3.0"
   ),
   .package(
     url: "https://github.com/swift-server/swift-service-lifecycle.git",
@@ -145,8 +145,10 @@ let targets: [Target] = [
     dependencies: [
       .target(name: "GRPCOTelTracingInterceptors"),
       .product(name: "GRPCCore", package: "grpc-swift-2"),
+      .product(name: "GRPCInProcessTransport", package: "grpc-swift-2"),
       .product(name: "GRPCProtobuf", package: "grpc-swift-protobuf"),
       .product(name: "Tracing", package: "swift-distributed-tracing"),
+      .product(name: "InMemoryTracing", package: "swift-distributed-tracing"),
     ],
     swiftSettings: defaultSwiftSettings
   ),

Sources/GRPCOTelTracingInterceptors/Tracing/ClientOTelTracingInterceptor.swift

@@ -38,6 +38,7 @@ public struct ClientOTelTracingInterceptor: ClientInterceptor {
   private let traceEachMessage: Bool
   private var includeRequestMetadata: Bool
   private var includeResponseMetadata: Bool
+  private let tracerOverride: (any Tracer)?
 
   /// Create a new instance of a ``ClientOTelTracingInterceptor``.
   ///
@@ -80,13 +81,32 @@ public struct ClientOTelTracingInterceptor: ClientInterceptor {
     traceEachMessage: Bool = true,
     includeRequestMetadata: Bool = false,
     includeResponseMetadata: Bool = false
+  ) {
+    self.init(
+      serverHostname: serverHostname,
+      networkTransportMethod: networkTransportMethod,
+      traceEachMessage: traceEachMessage,
+      includeRequestMetadata: includeRequestMetadata,
+      includeResponseMetadata: includeResponseMetadata,
+      tracerOverride: nil
+    )
+  }
+
+  package init(
+    serverHostname: String,
+    networkTransportMethod: String,
+    traceEachMessage: Bool,
+    includeRequestMetadata: Bool,
+    includeResponseMetadata: Bool,
+    tracerOverride: (any Tracer)?
   ) {
     self.injector = ClientRequestInjector()
     self.serverHostname = serverHostname
     self.networkTransportMethod = networkTransportMethod
     self.traceEachMessage = traceEachMessage
     self.includeRequestMetadata = includeRequestMetadata
     self.includeResponseMetadata = includeResponseMetadata
+    self.tracerOverride = tracerOverride
   }
 
   /// This interceptor will inject as the request's metadata whatever `ServiceContext` key-value pairs
@@ -108,7 +128,7 @@ public struct ClientOTelTracingInterceptor: ClientInterceptor {
     ) async throws -> StreamingClientResponse<Output>
   ) async throws -> StreamingClientResponse<Output> where Input: Sendable, Output: Sendable {
     try await self.intercept(
-      tracer: InstrumentationSystem.tracer,
+      tracer: self.tracerOverride ?? InstrumentationSystem.tracer,
       request: request,
       context: context,
       next: next

Sources/GRPCOTelTracingInterceptors/Tracing/ServerOTelTracingInterceptor.swift

@@ -38,6 +38,8 @@ public struct ServerOTelTracingInterceptor: ServerInterceptor {
   private var includeRequestMetadata: Bool
   private var includeResponseMetadata: Bool
 
+  private var tracerOverride: (any Tracer)?
+
   /// Create a new instance of a ``ServerOTelTracingInterceptor``.
   ///
   /// - Parameters:
@@ -79,13 +81,32 @@ public struct ServerOTelTracingInterceptor: ServerInterceptor {
     traceEachMessage: Bool = true,
     includeRequestMetadata: Bool = false,
     includeResponseMetadata: Bool = false
+  ) {
+    self.init(
+      serverHostname: serverHostname,
+      networkTransportMethod: networkTransportMethod,
+      traceEachMessage: traceEachMessage,
+      includeRequestMetadata: includeRequestMetadata,
+      includeResponseMetadata: includeResponseMetadata,
+      tracerOverride: nil
+    )
+  }
+
+  package init(
+    serverHostname: String,
+    networkTransportMethod: String,
+    traceEachMessage: Bool,
+    includeRequestMetadata: Bool,
+    includeResponseMetadata: Bool,
+    tracerOverride: (any Tracer)?
   ) {
     self.extractor = ServerRequestExtractor()
     self.traceEachMessage = traceEachMessage
     self.serverHostname = serverHostname
     self.networkTransportMethod = networkTransportMethod
     self.includeRequestMetadata = includeRequestMetadata
     self.includeResponseMetadata = includeResponseMetadata
+    self.tracerOverride = tracerOverride
   }
 
   /// This interceptor will extract whatever `ServiceContext` key-value pairs have been inserted into the
@@ -107,7 +128,7 @@ public struct ServerOTelTracingInterceptor: ServerInterceptor {
       StreamingServerResponse<Output>
   ) async throws -> StreamingServerResponse<Output> where Input: Sendable, Output: Sendable {
     try await self.intercept(
-      tracer: InstrumentationSystem.tracer,
+      tracer: self.tracerOverride ?? InstrumentationSystem.tracer,
       request: request,
       context: context,
       next: next

Tests/GRPCOTelTracingInterceptorsTests/Echo/EchoService.swift

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2025, gRPC Authors All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+internal import GRPCCore
+internal import SwiftProtobuf
+
+@available(gRPCSwiftExtras 2.0, *)
+struct EchoService: Echo_Echo.ServiceProtocol {
+  func get(
+    request: ServerRequest<Echo_EchoRequest>,
+    context: ServerContext
+  ) async throws -> ServerResponse<Echo_EchoResponse> {
+    return ServerResponse(message: .with { $0.text = request.message.text })
+  }
+
+  func collect(
+    request: StreamingServerRequest<Echo_EchoRequest>,
+    context: ServerContext
+  ) async throws -> ServerResponse<Echo_EchoResponse> {
+    let messages = try await request.messages.reduce(into: []) { $0.append($1.text) }
+    let joined = messages.joined(separator: " ")
+    return ServerResponse(message: .with { $0.text = joined })
+  }
+
+  func expand(
+    request: ServerRequest<Echo_EchoRequest>,
+    context: ServerContext
+  ) async throws -> StreamingServerResponse<Echo_EchoResponse> {
+    return StreamingServerResponse { response in
+      let parts = request.message.text.split(separator: " ")
+      let messages = parts.map { part in Echo_EchoResponse.with { $0.text = String(part) } }
+      try await response.write(contentsOf: messages)
+
+      return [:]
+    }
+  }
+
+  func update(
+    request: StreamingServerRequest<Echo_EchoRequest>,
+    context: ServerContext
+  ) async throws -> StreamingServerResponse<Echo_EchoResponse> {
+    return StreamingServerResponse { response in
+      for try await message in request.messages {
+        try await response.write(.with { $0.text = message.text })
+      }
+
+      return [:]
+    }
+  }
+}