Verify if tests communicate with just spawned dev server

Package.swift

@@ -116,7 +116,10 @@ let package = Package(
         "WebDriver",
         "WasmTransformer",
       ],
-      exclude: ["Utilities/README.md"]
+      exclude: ["Utilities/README.md"],
+      swiftSettings: [
+        .enableUpcomingFeature("BareSlashRegexLiterals")
+      ]
     ),
     .target(
       name: "SwiftToolchain",

Plugins/CartonDevPlugin/CartonDevPluginCommand.swift

@@ -21,12 +21,17 @@ struct CartonDevPluginCommand: CommandPlugin {
     var product: String?
     var release: Bool
     var verbose: Bool
+    var pid: String?
 
     static func parse(from extractor: inout ArgumentExtractor) throws -> Options {
       let product = extractor.extractOption(named: "product").last
       let release = extractor.extractFlag(named: "release")
       let verbose = extractor.extractFlag(named: "verbose")
-      return Options(product: product, release: release != 0, verbose: verbose != 0)
+      let pid = extractor.extractOption(named: "pid").last
+      return Options(
+        product: product, release: release != 0, verbose: verbose != 0,
+        pid: pid
+      )
     }
   }
 
@@ -82,19 +87,19 @@ struct CartonDevPluginCommand: CommandPlugin {
     let buildRequestPipe = try createFifo(hint: "build-request", directory: tempDirectory)
     let buildResponsePipe = try createFifo(hint: "build-response", directory: tempDirectory)
 
-    let frontend = try makeCartonFrontendProcess(
-      context: context,
-      arguments: [
-        "dev",
-        "--main-wasm-path", productArtifact.path.string,
-        "--build-request", buildRequestPipe,
-        "--build-response", buildResponsePipe,
-      ]
-        + resourcesPaths.flatMap { ["--resources", $0.string] }
-        + pathsToWatch.flatMap { ["--watch-path", $0] }
-        + (options.verbose ? ["--verbose"] : [])
-        + extractor.remainingArguments
-    )
+    var args: [String] = [
+      "dev",
+      "--main-wasm-path", productArtifact.path.string,
+      "--build-request", buildRequestPipe,
+      "--build-response", buildResponsePipe
+    ]
+    args += (options.pid.map { ["--pid", $0] } ?? [])
+    args += resourcesPaths.flatMap { ["--resources", $0.string] }
+    args += pathsToWatch.flatMap { ["--watch-path", $0] }
+    args += (options.verbose ? ["--verbose"] : [])
+    args += extractor.remainingArguments
+
+    let frontend = try makeCartonFrontendProcess(context: context, arguments: args)
     frontend.forwardTerminationSignals()
 
     try frontend.run()

Plugins/CartonTestPlugin/CartonTestPluginCommand.swift

@@ -20,11 +20,16 @@ struct CartonTestPluginCommand: CommandPlugin {
   struct Options {
     var environment: Environment
     var prebuiltTestBundlePath: String?
+    var pid: String?
 
     static func parse(from extractor: inout ArgumentExtractor) throws -> Options {
       let environment = try Environment.parse(from: &extractor)
       let prebuiltTestBundlePath = extractor.extractOption(named: "prebuilt-test-bundle-path").first
-      return Options(environment: environment, prebuiltTestBundlePath: prebuiltTestBundlePath)
+      let pid = extractor.extractOption(named: "pid").last
+      return Options(
+        environment: environment, prebuiltTestBundlePath: prebuiltTestBundlePath,
+        pid: pid
+      )
     }
   }
 
@@ -98,17 +103,18 @@ struct CartonTestPluginCommand: CommandPlugin {
       package: context.package
     )
 
-    let frontendArguments =
-      [
-        "test",
-        "--prebuilt-test-bundle-path", testProductArtifactPath,
-        "--environment", options.environment.rawValue,
-        "--plugin-work-directory", context.pluginWorkDirectory.string
-      ]
-      + resourcesPaths.flatMap {
-        ["--resources", $0.string]
-      } + extractor.remainingArguments
-    let frontend = try makeCartonFrontendProcess(context: context, arguments: frontendArguments)
+    var args: [String] = [
+      "test",
+      "--prebuilt-test-bundle-path", testProductArtifactPath,
+      "--environment", options.environment.rawValue,
+      "--plugin-work-directory", context.pluginWorkDirectory.string
+    ]
+    args += (options.pid.map { ["--pid", $0] } ?? [])
+    args += resourcesPaths.flatMap {
+      ["--resources", $0.string]
+    }
+    args += extractor.remainingArguments
+    let frontend = try makeCartonFrontendProcess(context: context, arguments: args)
     try frontend.checkRun(printsLoadingMessage: false, forwardExit: true)
   }
 

Sources/CartonCore/CartonCoreError.swift

@@ -1,6 +1,6 @@
-struct CartonCoreError: Error & CustomStringConvertible {
-  init(_ description: String) {
+public struct CartonCoreError: Error & CustomStringConvertible {
+  public init(_ description: String) {
     self.description = description
   }
-  var description: String
+  public  var description: String
 }

Sources/CartonDriver/CartonDriverCommand.swift

@@ -54,6 +54,8 @@ func derivePackageCommandArguments(
   let pluginArguments: [String] = ["plugin"]
   var cartonPluginArguments: [String] = extraArguments
 
+  let pid = ProcessInfo.processInfo.processIdentifier
+
   switch subcommand {
   case "bundle":
     packageArguments += ["--disable-sandbox"]
@@ -64,6 +66,7 @@ func derivePackageCommandArguments(
     cartonPluginArguments = ["--output", "Bundle"] + cartonPluginArguments
   case "dev":
     packageArguments += ["--disable-sandbox"]
+    cartonPluginArguments += ["--pid", pid.description]
   case "test":
     // 1. Ask the plugin process to generate the build command based on the given options
     let commandFile = try makeTemporaryFile(prefix: "test-build")
@@ -92,6 +95,7 @@ func derivePackageCommandArguments(
 
     // "--environment browser" launches a http server
     packageArguments += ["--disable-sandbox"]
+    cartonPluginArguments += ["--pid", pid.description]
   default: break
   }
 

Sources/CartonFrontend/Commands/CartonFrontendDevCommand.swift

@@ -113,6 +113,8 @@ struct CartonFrontendDevCommand: AsyncParsableCommand {
   )
   var mainWasmPath: String
 
+  @Option(name: .long, help: .hidden) var pid: Int32?
+
   static let configuration = CommandConfiguration(
     commandName: "dev",
     abstract: "Watch the current directory, host the app, rebuild on change."
@@ -169,6 +171,7 @@ struct CartonFrontendDevCommand: AsyncParsableCommand {
         },
         resourcesPaths: resources,
         entrypoint: Self.entrypoint,
+        pid: pid,
         terminal: terminal
       )
     )

Sources/CartonFrontend/Commands/CartonFrontendTestCommand.swift

@@ -96,6 +96,8 @@ struct CartonFrontendTestCommand: AsyncParsableCommand {
   ))
   var pluginWorkDirectory: String = "./"
 
+  @Option(name: .long, help: .hidden) var pid: Int32?
+
   func validate() throws {
     if headless && environment != .browser {
       throw TestError(
@@ -133,6 +135,7 @@ struct CartonFrontendTestCommand: AsyncParsableCommand {
         port: port,
         headless: headless,
         resourcesPaths: resources,
+        pid: pid,
         terminal: terminal
       ).run()
     case .node:

Sources/CartonFrontend/Commands/TestRunners/BrowserTestRunner.swift

@@ -53,6 +53,7 @@ struct BrowserTestRunner: TestRunner {
   let port: Int
   let headless: Bool
   let resourcesPaths: [String]
+  let pid: Int32?
   let terminal: InteractiveWriter
   let eventLoopGroup = MultiThreadedEventLoopGroup(numberOfThreads: 1)
 
@@ -63,6 +64,7 @@ struct BrowserTestRunner: TestRunner {
     port: Int,
     headless: Bool,
     resourcesPaths: [String],
+    pid: Int32?,
     terminal: InteractiveWriter
   ) {
     self.testFilePath = testFilePath
@@ -71,6 +73,7 @@ struct BrowserTestRunner: TestRunner {
     self.port = port
     self.headless = headless
     self.resourcesPaths = resourcesPaths
+    self.pid = pid
     self.terminal = terminal
   }
 
@@ -86,6 +89,7 @@ struct BrowserTestRunner: TestRunner {
         customIndexPath: nil,
         resourcesPaths: resourcesPaths,
         entrypoint: Constants.entrypoint,
+        pid: pid,
         terminal: terminal
       )
     )

Sources/CartonKit/Server/Server.swift

@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+import CartonCore
 import CartonHelpers
 import Foundation
 import Logging
@@ -106,6 +107,42 @@ public actor Server {
       hasher.combine(ObjectIdentifier(self))
     }
   }
+
+  public static let serverName = "carton dev server"
+
+  public struct ServerNameField: CustomStringConvertible {
+    public init(
+      name: String = serverName,
+      version: String = cartonVersion,
+      pid: Int32
+    ) {
+      self.name = name
+      self.version = version
+      self.pid = pid
+    }
+
+    public var name: String
+    public var version: String
+    public var pid: Int32
+
+    public var description: String {
+      "\(name)/\(version) (PID \(pid))"
+    }
+
+    private static let regex = #/([\w ]+)/([\w\.]+) \(PID (\d+)\)/#
+
+    public static func parse(_ string: String) throws -> ServerNameField {
+      guard let m = try regex.wholeMatch(in: string),
+            let pid = Int32(m.output.3) else {
+        throw CartonCoreError("invalid server name: \(string)")
+      }
+
+      let name = String(m.output.1)
+      let version = String(m.output.2)
+      return ServerNameField(name: name, version: version, pid: pid)
+    }
+  }
+
   /// Used for decoding `Event` values sent from the WebSocket client.
   private let decoder = JSONDecoder()
 
@@ -131,6 +168,8 @@ public actor Server {
 
   private let configuration: Configuration
 
+  private let serverName: ServerNameField
+
   public struct Configuration {
     let builder: BuilderProtocol?
     let mainWasmPath: AbsolutePath
@@ -141,6 +180,7 @@ public actor Server {
     let customIndexPath: AbsolutePath?
     let resourcesPaths: [String]
     let entrypoint: Entrypoint
+    let pid: Int32?
     let terminal: InteractiveWriter
 
     public init(
@@ -153,6 +193,7 @@ public actor Server {
       customIndexPath: AbsolutePath?,
       resourcesPaths: [String],
       entrypoint: Entrypoint,
+      pid: Int32?,
       terminal: InteractiveWriter
     ) {
       self.builder = builder
@@ -164,6 +205,7 @@ public actor Server {
       self.customIndexPath = customIndexPath
       self.resourcesPaths = resourcesPaths
       self.entrypoint = entrypoint
+      self.pid = pid
       self.terminal = terminal
     }
 
@@ -184,6 +226,9 @@ public actor Server {
     self.localURL = localURL
     watcher = nil
     self.configuration = configuration
+    self.serverName = ServerNameField(
+      pid: configuration.pid ?? ProcessInfo.processInfo.processIdentifier
+    )
 
     guard let builder = configuration.builder else {
       return
@@ -293,7 +338,8 @@ public actor Server {
       mainWasmPath: configuration.mainWasmPath,
       customIndexPath: configuration.customIndexPath,
       resourcesPaths: configuration.resourcesPaths,
-      entrypoint: configuration.entrypoint
+      entrypoint: configuration.entrypoint,
+      serverName: serverName.description
     )
     let channel = try await ServerBootstrap(group: group)
       // Specify backlog and enable SO_REUSEADDR for the server itself

Sources/CartonKit/Server/ServerHTTPHandler.swift

@@ -28,6 +28,7 @@ final class ServerHTTPHandler: ChannelInboundHandler, RemovableChannelHandler {
     let customIndexPath: AbsolutePath?
     let resourcesPaths: [String]
     let entrypoint: Entrypoint
+    let serverName: String
   }
 
   let configuration: Configuration
@@ -93,6 +94,7 @@ final class ServerHTTPHandler: ChannelInboundHandler, RemovableChannelHandler {
     self.responseBody = response.body
 
     var headers = HTTPHeaders()
+    headers.add(name: "Server", value: configuration.serverName)
     headers.add(name: "Content-Type", value: response.contentType)
     headers.add(name: "Content-Length", value: String(response.body.readableBytes))
     headers.add(name: "Connection", value: "close")

Tests/CartonCommandTests/CommandTestHelper.swift

@@ -15,6 +15,7 @@
 import ArgumentParser
 import XCTest
 import CartonHelpers
+import CartonKit
 
 #if canImport(FoundationNetworking)
   import FoundationNetworking
@@ -91,8 +92,10 @@ func swiftRunProcess(
       stdout: { (chunk) in
         outputBuffer += chunk
         stdoutStream.write(sequence: chunk)
+        stdoutStream.flush()
       }, stderr: { (chunk) in
         stderrStream.write(sequence: chunk)
+        stderrStream.flush()
       },
       redirectStderr: false
     )
@@ -134,3 +137,18 @@ func fetchWebContent(at url: URL, timeout: Duration) async throws -> (response:
 
   return (response: response, body: body)
 }
+
+func checkServerNameField(response: HTTPURLResponse, expectedPID: Int32) throws {
+  guard let string = response.value(forHTTPHeaderField: "Server") else {
+    throw CommandTestError("no Server header")
+  }
+  let field = try Server.ServerNameField.parse(string)
+
+  guard field.name == Server.serverName else {
+    throw CommandTestError("invalid server name: \(field)")
+  }
+
+  guard field.pid == expectedPID else {
+    throw CommandTestError("Expected PID \(expectedPID) but got PID \(field.pid).")
+  }
+}

Tests/CartonCommandTests/DevCommandTests.swift

@@ -82,6 +82,7 @@ final class DevCommandTests: XCTestCase {
 
     let (response, data) = try await fetchDevServerWithRetry(at: try URL(string: url).unwrap("url"))
     XCTAssertEqual(response.statusCode, 200, "Response was not ok")
+    try checkServerNameField(response: response, expectedPID: process.process.processID)
 
     let expectedHtml = """
       <!DOCTYPE html>