feat: Adding more tests

.swiftformat

@@ -8,3 +8,4 @@
 --wrapconditions after-first
 --typeblanklines preserve
 --commas inline
+--stripunusedargs closure-only

Dockerfile

@@ -11,4 +11,4 @@ RUN swift build --enable-test-discovery -c release -Xswiftc -g
 FROM swift:5.10-slim
 WORKDIR /run
 COPY --from=build /build/.build/release/dewPoint-controller /run
-CMD ["/bin/bash", "-xc", "./dewPoint-controller"]
+CMD ["/bin/bash", "-xc", "./dewpoint-controller"]

Makefile

@@ -23,7 +23,7 @@ stop-mosquitto:
 	@docker-compose rm -f mosquitto || true
 
 test-docker:
-	@docker-compose run --remove-orphans -i --rm test
+	@docker-compose run --build --remove-orphans -i --rm test
 	@docker-compose kill mosquitto-test
 	@docker-compose rm -f
 

Package.swift

@@ -8,17 +8,20 @@ let swiftSettings: [SwiftSetting] = [
 ]
 
 let package = Package(
-  name: "dewPoint-controller",
+  name: "dewpoint-controller",
   platforms: [
     .macOS(.v14)
   ],
   products: [
-    .executable(name: "dewPoint-controller", targets: ["dewPoint-controller"]),
+    .executable(name: "dewpoint-controller", targets: ["dewpoint-controller"]),
     .library(name: "Models", targets: ["Models"]),
+    .library(name: "MQTTConnectionManager", targets: ["MQTTConnectionManager"]),
     .library(name: "MQTTConnectionService", targets: ["MQTTConnectionService"]),
-    .library(name: "SensorsService", targets: ["SensorsService"])
+    .library(name: "SensorsService", targets: ["SensorsService"]),
+    .library(name: "TopicDependencies", targets: ["TopicDependencies"])
   ],
   dependencies: [
+    .package(url: "https://github.com/apple/swift-async-algorithms", from: "1.0.0"),
     .package(url: "https://github.com/apple/swift-nio", from: "2.0.0"),
     .package(url: "https://github.com/apple/swift-log", from: "1.6.0"),
     .package(url: "https://github.com/pointfreeco/swift-dependencies", from: "1.4.1"),
@@ -28,20 +31,18 @@ let package = Package(
   ],
   targets: [
     .executableTarget(
-      name: "dewPoint-controller",
+      name: "dewpoint-controller",
       dependencies: [
         "Models",
+        "MQTTConnectionManager",
         "MQTTConnectionService",
         "SensorsService",
+        "TopicDependencies",
         .product(name: "MQTTNIO", package: "mqtt-nio"),
         .product(name: "NIO", package: "swift-nio"),
         .product(name: "PsychrometricClientLive", package: "swift-psychrometrics")
       ]
     ),
-    .testTarget(
-      name: "dewPoint-controllerTests",
-      dependencies: ["dewPoint-controller"]
-    ),
     .target(
       name: "Models",
       dependencies: [
@@ -50,11 +51,21 @@ let package = Package(
       ],
       swiftSettings: swiftSettings
     ),
+    .target(
+      name: "MQTTConnectionManager",
+      dependencies: [
+        .product(name: "AsyncAlgorithms", package: "swift-async-algorithms"),
+        .product(name: "Dependencies", package: "swift-dependencies"),
+        .product(name: "DependenciesMacros", package: "swift-dependencies"),
+        .product(name: "MQTTNIO", package: "mqtt-nio")
+      ],
+      swiftSettings: swiftSettings
+    ),
     .target(
       name: "MQTTConnectionService",
       dependencies: [
         "Models",
-        .product(name: "MQTTNIO", package: "mqtt-nio"),
+        "MQTTConnectionManager",
         .product(name: "ServiceLifecycle", package: "swift-service-lifecycle")
       ],
       swiftSettings: swiftSettings
@@ -63,6 +74,7 @@ let package = Package(
       name: "MQTTConnectionServiceTests",
       dependencies: [
         "MQTTConnectionService",
+        "MQTTConnectionManager",
         .product(name: "ServiceLifecycleTestKit", package: "swift-service-lifecycle")
       ]
     ),
@@ -71,6 +83,7 @@ let package = Package(
       dependencies: [
         "Models",
         "MQTTConnectionService",
+        "TopicDependencies",
         .product(name: "Dependencies", package: "swift-dependencies"),
         .product(name: "DependenciesMacros", package: "swift-dependencies"),
         .product(name: "MQTTNIO", package: "mqtt-nio"),
@@ -84,6 +97,15 @@ let package = Package(
         "SensorsService",
         .product(name: "PsychrometricClientLive", package: "swift-psychrometrics")
       ]
+    ),
+    .target(
+      name: "TopicDependencies",
+      dependencies: [
+        .product(name: "Dependencies", package: "swift-dependencies"),
+        .product(name: "DependenciesMacros", package: "swift-dependencies"),
+        .product(name: "MQTTNIO", package: "mqtt-nio")
+      ],
+      swiftSettings: swiftSettings
     )
   ]
 )

Sources/MQTTConnectionManager/Live.swift

@@ -0,0 +1,199 @@
+import AsyncAlgorithms
+import Dependencies
+import DependenciesMacros
+import Foundation
+import Logging
+import MQTTNIO
+import NIO
+
+public extension DependencyValues {
+
+  /// A dependency that is responsible for managing the connection to
+  /// an MQTT broker.
+  var mqttConnectionManager: MQTTConnectionManager {
+    get { self[MQTTConnectionManager.self] }
+    set { self[MQTTConnectionManager.self] = newValue }
+  }
+}
+
+/// Represents the interface needed for the ``MQTTConnectionService``.
+///
+/// See ``MQTTConnectionManagerLive`` module for live implementation.
+@DependencyClient
+public struct MQTTConnectionManager: Sendable {
+
+  /// Connect to the MQTT broker.
+  public var connect: @Sendable () async throws -> Void
+
+  /// Shutdown the connection to the MQTT broker.
+  ///
+  /// - Note: You should cancel any tasks that are listening to the connection stream first.
+  public var shutdown: @Sendable () -> Void
+
+  /// Create a stream of connection events.
+  public var stream: @Sendable () throws -> AsyncStream<Event>
+
+  /// Represents connection events that clients can listen for and
+  /// react accordingly.
+  public enum Event: Sendable {
+    case connected
+    case disconnected
+    case shuttingDown
+  }
+
+  public static func live(
+    client: MQTTClient,
+    cleanSession: Bool = false,
+    logger: Logger? = nil,
+    alwaysReconnect: Bool = true
+  ) -> Self {
+    let manager = ConnectionManager(
+      client: client,
+      logger: logger,
+      alwaysReconnect: alwaysReconnect
+    )
+    return .init {
+      try await manager.connect(cleanSession: cleanSession)
+    } shutdown: {
+      manager.shutdown()
+    } stream: {
+      MQTTConnectionStream(client: client, logger: logger)
+        .start()
+        .removeDuplicates()
+        .eraseToStream()
+    }
+  }
+}
+
+extension MQTTConnectionManager: TestDependencyKey {
+  public static var testValue: MQTTConnectionManager {
+    Self()
+  }
+}
+
+// MARK: - Helpers
+
+final class MQTTConnectionStream: AsyncSequence, Sendable {
+
+  typealias AsyncIterator = AsyncStream<Element>.AsyncIterator
+  typealias Element = MQTTConnectionManager.Event
+
+  private let client: MQTTClient
+  private let continuation: AsyncStream<Element>.Continuation
+  private let logger: Logger?
+  private let name: String
+  private let stream: AsyncStream<Element>
+
+  init(client: MQTTClient, logger: Logger?) {
+    let (stream, continuation) = AsyncStream<Element>.makeStream()
+    self.client = client
+    self.continuation = continuation
+    self.logger = logger
+    self.name = UUID().uuidString
+    self.stream = stream
+  }
+
+  deinit { stop() }
+
+  func start(
+    isolation: isolated (any Actor)? = #isolation
+  ) -> AsyncStream<Element> {
+    // Check if the client is active and yield the result.
+    continuation.yield(client.isActive() ? .connected : .disconnected)
+
+    // Register listener on the client for when the connection
+    // closes.
+    client.addCloseListener(named: name) { _ in
+      self.logger?.trace("Client has disconnected.")
+      self.continuation.yield(.disconnected)
+    }
+
+    // Register listener on the client for when the client
+    // is shutdown.
+    client.addShutdownListener(named: name) { _ in
+      self.logger?.trace("Client is shutting down.")
+      self.continuation.yield(.shuttingDown)
+      self.stop()
+    }
+
+    return stream
+  }
+
+  func stop() {
+    client.removeCloseListener(named: name)
+    client.removeShutdownListener(named: name)
+    continuation.finish()
+  }
+
+  public __consuming func makeAsyncIterator() -> AsyncIterator {
+    start().makeAsyncIterator()
+  }
+
+}
+
+actor ConnectionManager {
+  private let client: MQTTClient
+  private let logger: Logger?
+  private let name: String
+  private let shouldReconnect: Bool
+  private var hasConnected: Bool = false
+
+  init(
+    client: MQTTClient,
+    logger: Logger?,
+    alwaysReconnect: Bool
+  ) {
+    self.client = client
+    self.logger = logger
+    self.name = UUID().uuidString
+    self.shouldReconnect = alwaysReconnect
+  }
+
+  deinit {
+    // We should've already logged that we're shutting down if
+    // the manager was shutdown properly, so don't log it twice.
+    self.shutdown(withLogging: false)
+  }
+
+  private func setHasConnected() {
+    hasConnected = true
+  }
+
+  func connect(
+    isolation: isolated (any Actor)? = #isolation,
+    cleanSession: Bool
+  ) async throws {
+    guard !(await hasConnected) else { return }
+    do {
+      try await client.connect(cleanSession: cleanSession)
+      await setHasConnected()
+
+      client.addCloseListener(named: name) { [weak self] _ in
+        guard let `self` else { return }
+        self.logger?.debug("Connection closed.")
+        if self.shouldReconnect {
+          self.logger?.debug("Reconnecting...")
+          Task {
+            try await self.connect(cleanSession: cleanSession)
+          }
+        }
+      }
+
+      client.addShutdownListener(named: name) { _ in
+        self.shutdown()
+      }
+
+    } catch {
+      logger?.trace("Failed to connect: \(error)")
+      throw error
+    }
+  }
+
+  nonisolated func shutdown(withLogging: Bool = true) {
+    if withLogging {
+      logger?.trace("Shutting down connection.")
+    }
+    client.removeCloseListener(named: name)
+    client.removeShutdownListener(named: name)
+  }
+}

Sources/MQTTConnectionService/MQTTConnectionService.swift

@@ -1,151 +1,37 @@
-@preconcurrency import Foundation
+import Dependencies
 import Logging
 import Models
-import MQTTNIO
+import MQTTConnectionManager
-import NIO
 import ServiceLifecycle
 
-// TODO: This may not need to be an actor.
-
-/// Manages the MQTT broker connection.
 public actor MQTTConnectionService: Service {
+  @Dependency(\.mqttConnectionManager) var manager
 
-  private let cleanSession: Bool
+  private nonisolated let logger: Logger?
-  public let client: MQTTClient
-  private let continuation: AsyncStream<Event>.Continuation
-  public nonisolated let events: AsyncStream<Event>
-  private let internalEventStream: ConnectionStream
-  nonisolated var logger: Logger { client.logger }
-  // private var shuttingDown = false
 
   public init(
-    cleanSession: Bool = true,
+    logger: Logger? = nil
-    client: MQTTClient
   ) {
-    self.cleanSession = cleanSession
+    self.logger = logger
-    self.client = client
-    self.internalEventStream = .init()
-    let (stream, continuation) = AsyncStream.makeStream(of: Event.self)
-    self.events = stream
-    self.continuation = continuation
   }
 
-  deinit {
+  /// The entry-point of the service which starts the connection
-    self.logger.debug("MQTTConnectionService is gone.")
+  /// to the MQTT broker and handles graceful shutdown of the
-    self.internalEventStream.stop()
+  /// connection.
-    continuation.finish()
-  }
-
-  /// The entry-point of the service.
-  ///
-  /// This method connects to the MQTT broker and manages the connection.
-  /// It will attempt to gracefully shutdown the connection upon receiving
-  /// `sigterm` signals.
   public func run() async throws {
-    await withGracefulShutdownHandler {
+    try await withGracefulShutdownHandler {
-      await withDiscardingTaskGroup { group in
+      try await manager.connect()
-        group.addTask { await self.connect() }
+      for await event in try manager.stream().cancelOnGracefulShutdown() {
-        group.addTask {
+        // We don't really need to do anything with the events, so just logging
-          await self.internalEventStream.start { self.client.isActive() }
+        // for now.  But we need to iterate on an async stream for the service to
-        }
+        // continue to run and handle graceful shutdowns.
-        for await event in self.internalEventStream.events.cancelOnGracefulShutdown() {
+        logger?.trace("Received connection event: \(event)")
-          if event == .shuttingDown {
-            self.shutdown()
-            break
-          }
-          self.logger.trace("Sending connection event: \(event)")
-          self.continuation.yield(event)
-        }
-        group.cancelAll()
       }
+      // when we reach here we are shutting down, so we shutdown
+      // the manager.
+      manager.shutdown()
     } onGracefulShutdown: {
-      self.logger.trace("Received graceful shutdown.")
+      self.logger?.trace("Received graceful shutdown.")
-      self.shutdown()
     }
   }
-
-  func connect() async {
-    do {
-      try await withThrowingDiscardingTaskGroup { group in
-        group.addTask {
-          try await self.client.connect(cleanSession: self.cleanSession)
-        }
-        client.addCloseListener(named: "\(Self.self)") { _ in
-          Task {
-            self.logger.debug("Connection closed.")
-            self.logger.debug("Reconnecting...")
-            await self.connect()
-          }
-        }
-        self.logger.debug("Connection successful.")
-        self.continuation.yield(.connected)
-      }
-    } catch {
-      logger.trace("Failed to connect: \(error)")
-      continuation.yield(.disconnected)
-    }
-  }
-
-  private nonisolated func shutdown() {
-    logger.debug("Begin shutting down MQTT broker connection.")
-    client.removeCloseListener(named: "\(Self.self)")
-    internalEventStream.stop()
-    _ = client.disconnect()
-    try? client.syncShutdownGracefully()
-    continuation.finish()
-    logger.info("MQTT broker connection closed.")
-  }
-
-}
-
-extension MQTTConnectionService {
-
-  public enum Event: Sendable {
-    case connected
-    case disconnected
-    case shuttingDown
-  }
-
-  // TODO: This functionality can probably move into the connection service.
-
-  private final class ConnectionStream: Sendable {
-
-    // private var cancellable: AnyCancellable?
-    private let continuation: AsyncStream<MQTTConnectionService.Event>.Continuation
-    let events: AsyncStream<MQTTConnectionService.Event>
-
-    init() {
-      let (stream, continuation) = AsyncStream.makeStream(of: MQTTConnectionService.Event.self)
-      self.events = stream
-      self.continuation = continuation
-    }
-
-    deinit {
-      stop()
-    }
-
-    func start(isActive connectionIsActive: @escaping () -> Bool) async {
-      try? await Task.sleep(for: .seconds(1))
-      let event: MQTTConnectionService.Event = connectionIsActive()
-        ? .connected
-        : .disconnected
-
-      continuation.yield(event)
-//       cancellable = Timer.publish(every: 1.0, on: .main, in: .common)
-//         .autoconnect()
-//         .sink { [weak self] (_: Date) in
-//           let event: MQTTConnectionService.Event = connectionIsActive()
-//             ? .connected
-//             : .disconnected
-//
-//           self?.continuation.yield(event)
-//         }
-    }
-
-    func stop() {
-      continuation.yield(.shuttingDown)
-      continuation.finish()
-    }
-  }
-
 }

Sources/Models/TemperatureAndHumiditySensor.swift

@@ -56,10 +56,11 @@ public struct TemperatureAndHumiditySensor: Identifiable, Sendable {
   public var dewPoint: DewPoint? {
     get async {
       guard let temperature = temperature,
-            let humidity = humidity
+            let humidity = humidity,
+            !temperature.value.isNaN,
+            !humidity.value.isNaN
       else { return nil }
       return try? await psychrometrics.dewPoint(.dryBulb(temperature, relativeHumidity: humidity))
-      // return .init(dryBulb: temperature, humidity: humidity)
     }
   }
 
@@ -67,12 +68,13 @@ public struct TemperatureAndHumiditySensor: Identifiable, Sendable {
   public var enthalpy: EnthalpyOf<MoistAir>? {
     get async {
       guard let temperature = temperature,
-            let humidity = humidity
+            let humidity = humidity,
+            !temperature.value.isNaN,
+            !humidity.value.isNaN
       else { return nil }
       return try? await psychrometrics.enthalpy.moistAir(
         .dryBulb(temperature, relativeHumidity: humidity, altitude: altitude)
       )
-      // return .init(dryBulb: temperature, humidity: humidity, altitude: altitude)
     }
   }
 
@@ -129,10 +131,10 @@ public struct TemperatureAndHumiditySensor: Identifiable, Sendable {
         prefix = "\(prefix.dropLast())"
       }
       self.init(
-        dewPoint: "\(prefix)/sensors/\(location.rawValue)_dew_point/state",
+        dewPoint: "\(prefix)/sensor/\(location.rawValue)_dew_point/state",
-        enthalpy: "\(prefix)/sensors/\(location.rawValue)_enthalpy/state",
+        enthalpy: "\(prefix)/sensor/\(location.rawValue)_enthalpy/state",
-        humidity: "\(prefix)/sensors/\(location.rawValue)_humidity/state",
+        humidity: "\(prefix)/sensor/\(location.rawValue)_humidity/state",
-        temperature: "\(prefix)/sensors/\(location.rawValue)_temperature/state"
+        temperature: "\(prefix)/sensor/\(location.rawValue)_temperature/state"
       )
     }
   }

Sources/Models/TrackedChanges.swift

@@ -3,7 +3,7 @@
 /// This allows values to only publish changes if they have changed since the
 /// last time they were recieved.
 @propertyWrapper
-public struct TrackedChanges<Value> {
+public struct TrackedChanges<Value: Sendable>: Sendable {
 
   /// The current tracking state.
   private var tracking: TrackingState
@@ -12,7 +12,7 @@ public struct TrackedChanges<Value> {
   private var value: Value
 
   /// Used to check if a new value is equal to an old value.
-  private var isEqual: (Value, Value) -> Bool
+  private var isEqual: @Sendable (Value, Value) -> Bool
 
   /// Access to the underlying property that we are wrapping.
   public var wrappedValue: Value {
@@ -35,7 +35,7 @@ public struct TrackedChanges<Value> {
   public init(
     wrappedValue: Value,
     needsProcessed: Bool = false,
-    isEqual: @escaping (Value, Value) -> Bool
+    isEqual: @escaping @Sendable (Value, Value) -> Bool
   ) {
     self.value = wrappedValue
     self.tracking = needsProcessed ? .needsProcessed : .hasProcessed
@@ -85,7 +85,9 @@ extension TrackedChanges: Equatable where Value: Equatable {
     wrappedValue: Value,
     needsProcessed: Bool = false
   ) {
-    self.init(wrappedValue: wrappedValue, needsProcessed: needsProcessed, isEqual: ==)
+    self.init(wrappedValue: wrappedValue, needsProcessed: needsProcessed) {
+      $0 == $1
+    }
   }
 }
 
@@ -96,5 +98,3 @@ extension TrackedChanges: Hashable where Value: Hashable {
     hasher.combine(needsProcessed)
   }
 }
-
-extension TrackedChanges: Sendable where Value: Sendable {}

Sources/SensorsService/Helpers.swift

@@ -1,6 +1,3 @@
-import Logging
-import Models
-import MQTTNIO
 import NIO
 import NIOFoundationCompat
 import PsychrometricClient

Sources/SensorsService/SensorsService.swift

@@ -3,305 +3,160 @@ import DependenciesMacros
 import Foundation
 import Logging
 import Models
-import MQTTConnectionService
+import MQTTNIO
-@preconcurrency import MQTTNIO
 import NIO
 import PsychrometricClient
 import ServiceLifecycle
+import TopicDependencies
 
-@DependencyClient
+/// Service that is responsible for listening to changes of the temperature and humidity
-public struct SensorsClient: Sendable {
+/// sensors, then publishing back the calculated dew-point temperature and enthalpy for
+/// the sensor location.
+///
+///
+public actor SensorsService: Service {
 
-  public var listen: @Sendable ([String]) async throws -> AsyncStream<MQTTPublishInfo>
+  @Dependency(\.topicListener) var topicListener
-  public var logger: Logger?
+  @Dependency(\.topicPublisher) var topicPublisher
-  public var publish: @Sendable (Double, String) async throws -> Void
-  public var shutdown: @Sendable () -> Void = {}
 
-  public func listen(to topics: [String]) async throws -> AsyncStream<MQTTPublishInfo> {
+  /// The logger to use for the service.
-    try await listen(topics)
+  private let logger: Logger?
-  }
 
-  public func publish(_ value: Double, to topic: String) async throws {
+  /// The sensors that we are listening for updates to, so
-    try await publish(value, topic)
+  /// that we can calculate the dew-point temperature and enthalpy
-  }
+  /// values to publish back to the MQTT broker.
-}
+  var sensors: [TemperatureAndHumiditySensor]
 
-extension SensorsClient: TestDependencyKey {
+  var topics: [String] {
-  public static var testValue: SensorsClient {
-    Self()
-  }
-}
-
-public extension DependencyValues {
-  var sensorsClient: SensorsClient {
-    get { self[SensorsClient.self] }
-    set { self[SensorsClient.self] = newValue }
-  }
-}
-
-public actor SensorsService2: Service {
-
-  @Dependency(\.sensorsClient) var client
-
-  private var sensors: [TemperatureAndHumiditySensor]
-
-  public init(
-    sensors: [TemperatureAndHumiditySensor]
-  ) {
-    self.sensors = sensors
-  }
-
-  public func run() async throws {
-    guard sensors.count > 0 else {
-      throw SensorCountError()
-    }
-
-    let stream = try await client.listen(to: topics)
-
-    do {
-      try await withGracefulShutdownHandler {
-        try await withThrowingDiscardingTaskGroup { group in
-          for await result in stream.cancelOnGracefulShutdown() {
-            group.addTask { try await self.handleResult(result) }
-          }
-        }
-      } onGracefulShutdown: {
-        Task {
-          await self.client.logger?.trace("Received graceful shutdown.")
-          try? await self.publishUpdates()
-          await self.client.shutdown()
-        }
-      }
-    } catch {
-      client.logger?.trace("Error: \(error)")
-      client.shutdown()
-    }
-  }
-
-  private var topics: [String] {
     sensors.reduce(into: [String]()) { array, sensor in
       array.append(sensor.topics.temperature)
       array.append(sensor.topics.humidity)
     }
   }
 
-  private func handleResult(_ result: MQTTPublishInfo) async throws {
+  /// Create a new sensors service that listens to the passed in
-    let topic = result.topicName
+  /// sensors.
-    client.logger?.trace("Begin handling result for topic: \(topic)")
+  ///
+  /// - Note: The service will fail to start if the array of sensors is not greater than 0.
+  ///
+  /// - Parameters:
+  ///   - sensors: The sensors to listen for changes to.
+  ///   - logger: An optional logger to use.
+  public init(
+    sensors: [TemperatureAndHumiditySensor],
+    logger: Logger? = nil
+  ) {
+    self.sensors = sensors
+    self.logger = logger
+  }
+
+  /// Start the service with graceful shutdown, which will attempt to publish
+  /// any pending changes to the MQTT broker, upon a shutdown signal.
+  public func run() async throws {
+    precondition(sensors.count > 0, "Sensors should not be empty.")
+
+    let stream = try await makeStream()
+
+    await withGracefulShutdownHandler {
+      await withDiscardingTaskGroup { group in
+        for await result in stream.cancelOnGracefulShutdown() {
+          logger?.trace("Received result for topic: \(result.topic)")
+          group.addTask { await self.handleResult(result) }
+        }
+        // group.cancelAll()
+      }
+    } onGracefulShutdown: {
+      Task {
+        self.logger?.trace("Received graceful shutdown.")
+        try? await self.publishUpdates()
+        await self.topicListener.shutdown()
+      }
+    }
+  }
+
+  private func makeStream() async throws -> AsyncStream<(buffer: ByteBuffer, topic: String)> {
+    try await topicListener.listen(to: topics)
+      // ignore errors, so that we continue to listen, but log them
+      // for debugging purposes.
+      .compactMap { result in
+        switch result {
+        case let .failure(error):
+          self.logger?.trace("Received error listening for sensors: \(error)")
+          return nil
+        case let .success(info):
+          return (info.payload, info.topicName)
+        }
+      }
+      // ignore duplicate values, to prevent publishing dew-point and enthalpy
+      // changes to frequently.
+      .removeDuplicates { lhs, rhs in
+        lhs.buffer == rhs.buffer
+          && lhs.topic == rhs.topic
+      }
+      .eraseToStream()
+  }
+
+  private func handleResult(_ result: (buffer: ByteBuffer, topic: String)) async {
+    do {
+      let topic = result.topic
+      assert(topics.contains(topic))
+      logger?.trace("Begin handling result for topic: \(topic)")
 
       func decode<V: BufferInitalizable>(_: V.Type) -> V? {
-      var buffer = result.payload
+        var buffer = result.buffer
         return V(buffer: &buffer)
       }
 
       if topic.contains("temperature") {
-      client.logger?.trace("Begin handling temperature result.")
+        logger?.trace("Begin handling temperature result.")
         guard let temperature = decode(DryBulb.self) else {
-        client.logger?.trace("Failed to decode temperature: \(result.payload)")
+          logger?.trace("Failed to decode temperature: \(result.buffer)")
           throw DecodingError()
         }
-      client.logger?.trace("Decoded temperature: \(temperature)")
+        logger?.trace("Decoded temperature: \(temperature)")
         try sensors.update(topic: topic, keyPath: \.temperature, with: temperature)
 
       } else if topic.contains("humidity") {
-      client.logger?.trace("Begin handling humidity result.")
+        logger?.trace("Begin handling humidity result.")
         guard let humidity = decode(RelativeHumidity.self) else {
-        client.logger?.trace("Failed to decode humidity: \(result.payload)")
+          logger?.trace("Failed to decode humidity: \(result.buffer)")
           throw DecodingError()
         }
-      client.logger?.trace("Decoded humidity: \(humidity)")
+        logger?.trace("Decoded humidity: \(humidity)")
         try sensors.update(topic: topic, keyPath: \.humidity, with: humidity)
-    } else {
-      client.logger?.error("Received unexpected topic, expected topic to contain 'temperature' or 'humidity'!")
-      return
       }
 
       try await publishUpdates()
-    client.logger?.trace("Done handling result for topic: \(topic)")
+      logger?.trace("Done handling result for topic: \(topic)")
+    } catch {
+      logger?.error("Received error: \(error)")
+    }
   }
 
   private func publish(_ double: Double?, to topic: String) async throws {
     guard let double else { return }
-    try await client.publish(double, to: topic)
+    try await topicPublisher.publish(
-    client.logger?.trace("Published update to topic: \(topic)")
+      to: topic,
+      payload: ByteBufferAllocator().buffer(string: "\(double)"),
+      qos: .exactlyOnce,
+      retain: true
+    )
+    logger?.trace("Published update to topic: \(topic)")
   }
 
   private func publishUpdates() async throws {
     for sensor in sensors.filter(\.needsProcessed) {
       try await publish(sensor.dewPoint?.value, to: sensor.topics.dewPoint)
       try await publish(sensor.enthalpy?.value, to: sensor.topics.enthalpy)
-    }
-  }
-}
-
-public actor SensorsService: Service {
-  private var sensors: [TemperatureAndHumiditySensor]
-  private let client: MQTTClient
-  private let events: @Sendable () -> AsyncStream<MQTTConnectionService.Event>
-  nonisolated var logger: Logger { client.logger }
-  private var shuttingDown: Bool = false
-
-  public init(
-    client: MQTTClient,
-    events: @Sendable @escaping () -> AsyncStream<MQTTConnectionService.Event>,
-    sensors: [TemperatureAndHumiditySensor]
-  ) {
-    self.client = client
-    self.events = events
-    self.sensors = sensors
-  }
-
-  /// The entry-point of the service.
-  ///
-  /// This method is called to start the service and begin
-  /// listening for sensor value changes then publishing the dew-point
-  /// and enthalpy values of the sensors.
-  public func run() async throws {
-    do {
-      try await withGracefulShutdownHandler {
-        try await withThrowingDiscardingTaskGroup { group in
-          client.addPublishListener(named: "\(Self.self)") { result in
-            if self.shuttingDown {
-              self.logger.trace("Shutting down.")
-            } else if !self.client.isActive() {
-              self.logger.trace("Client is not currently active")
-            } else {
-              Task { try await self.handleResult(result) }
-            }
-          }
-          for await event in self.events().cancelOnGracefulShutdown() {
-            logger.trace("Received event: \(event)")
-            if event == .shuttingDown {
-              self.setIsShuttingDown()
-            } else if event == .connected {
-              group.addTask { try await self.subscribeToSensors() }
-            } else {
-              group.addTask { await self.unsubscribeToSensors() }
-              group.addTask { try? await Task.sleep(for: .milliseconds(100)) }
-            }
-          }
-        }
-      } onGracefulShutdown: {
-        // do something.
-        self.logger.debug("Received graceful shutdown.")
-        Task { [weak self] in await self?.setIsShuttingDown() }
-      }
-    } catch {
-      // WARN: We always get an MQTTNIO `noConnection` error here, which generally is not an issue,
-      // but causes service ServiceLifecycle to fail, so currently just ignoring errors that are thrown.
-      // However we do receive the unsubscribe message back from the MQTT broker, so it is likely safe
-      // to ignore the `noConnection` error.
-      logger.trace("Run error: \(error)")
-      // throw error
-    }
-  }
-
-  private func setIsShuttingDown() {
-    logger.debug("Received shut down event.")
-    Task { try await publishUpdates() }
-    Task { await self.unsubscribeToSensors() }
-    shuttingDown = true
-    client.removePublishListener(named: "\(Self.self)")
-  }
-
-  private func handleResult(
-    _ result: Result<MQTTPublishInfo, any Error>
-  ) async throws {
-    logger.trace("Begin handling result")
-    do {
-      switch result {
-      case let .failure(error):
-        logger.debug("Failed receiving sensor: \(error)")
-        throw error
-      case let .success(value):
-        // do something.
-        let topic = value.topicName
-        logger.trace("Received new value for topic: \(topic)")
-        if topic.contains("temperature") {
-          // do something.
-          var buffer = value.payload
-          guard let temperature = DryBulb(buffer: &buffer) else {
-            logger.trace("Decoding error for topic: \(topic)")
-            throw DecodingError()
-          }
-          try sensors.update(topic: topic, keyPath: \.temperature, with: temperature)
-          try await publishUpdates()
-
-        } else if topic.contains("humidity") {
-          var buffer = value.payload
-          // Decode and update the temperature value
-          guard let humidity = RelativeHumidity(buffer: &buffer) else {
-            logger.debug("Failed to decode humidity from buffer: \(buffer)")
-            throw DecodingError()
-          }
-          try sensors.update(topic: topic, keyPath: \.humidity, with: humidity)
-          try await publishUpdates()
-        }
-      }
-    } catch {
-      logger.trace("Handle Result error: \(error)")
-      throw error
-    }
-  }
-
-  private func subscribeToSensors() async throws {
-    for sensor in sensors {
-      _ = try await client.subscribe(to: [
-        MQTTSubscribeInfo(topicFilter: sensor.topics.temperature, qos: .atLeastOnce),
-        MQTTSubscribeInfo(topicFilter: sensor.topics.humidity, qos: .atLeastOnce)
-      ])
-      logger.debug("Subscribed to sensor: \(sensor.location)")
-    }
-  }
-
-  private func unsubscribeToSensors() async {
-    logger.trace("Begin unsubscribe to sensors.")
-    guard client.isActive() else {
-      logger.debug("Client is not active, skipping.")
-      return
-    }
-    do {
-      let topics = sensors.reduce(into: [String]()) { array, sensor in
-        array.append(sensor.topics.temperature)
-        array.append(sensor.topics.humidity)
-      }
-      try await client.unsubscribe(from: topics)
-      logger.trace("Unsubscribed from sensors.")
-    } catch {
-      logger.trace("Unsubscribe error: \(error)")
-    }
-  }
-
-  private func publish(double: Double?, to topic: String) async throws {
-    guard client.isActive() else { return }
-    guard let double else { return }
-    let rounded = round(double * 100) / 100
-    logger.debug("Publishing \(rounded), to: \(topic)")
-    try await client.publish(
-      to: topic,
-      payload: ByteBufferAllocator().buffer(string: "\(rounded)"),
-      qos: .exactlyOnce,
-      retain: true
-    )
-  }
-
-  private func publishUpdates() async throws {
-    for sensor in sensors.filter(\.needsProcessed) {
-      try await publish(double: sensor.dewPoint?.value, to: sensor.topics.dewPoint)
-      try await publish(double: sensor.enthalpy?.value, to: sensor.topics.enthalpy)
       try sensors.hasProcessed(sensor)
     }
   }
-
 }
 
 // MARK: - Errors
 
 struct DecodingError: Error {}
-struct MQTTClientNotConnected: Error {}
+struct SensorNotFoundError: Error {}
-struct NotFoundError: Error {}
-struct SensorExists: Error {}
-struct SensorCountError: Error {}
 
 // MARK: - Helpers
 
@@ -319,14 +174,14 @@ private extension Array where Element == TemperatureAndHumiditySensor {
     with value: V
   ) throws {
     guard let index = firstIndex(where: { $0.topics.contains(topic) }) else {
-      throw NotFoundError()
+      throw SensorNotFoundError()
     }
     self[index][keyPath: keyPath] = value
   }
 
   mutating func hasProcessed(_ sensor: TemperatureAndHumiditySensor) throws {
     guard let index = firstIndex(where: { $0.id == sensor.id }) else {
-      throw NotFoundError()
+      throw SensorNotFoundError()
     }
     self[index].needsProcessed = false
   }

Sources/TopicDependencies/TopicListener.swift

@@ -0,0 +1,183 @@
+import Dependencies
+import DependenciesMacros
+import Foundation
+import MQTTNIO
+
+/// A dependency that can generate an async stream of changes to the given topics.
+///
+/// - Note: This type only conforms to ``TestDependencyKey`` because it requires an MQTTClient
+/// to generate the live dependency.
+@DependencyClient
+public struct TopicListener: Sendable {
+
+  public typealias Stream = AsyncStream<Result<MQTTPublishInfo, MQTTListenResultError>>
+
+  /// Create an async stream that listens for changes to the given topics.
+  private var _listen: @Sendable ([String], MQTTQoS) async throws -> Stream
+
+  /// Shutdown the listener stream.
+  public var shutdown: @Sendable () -> Void
+
+  /// Create a new topic listener.
+  ///
+  /// - Parameters:
+  ///   - listen: Generate an async stream of changes for the given topics.
+  ///   - shutdown: Shutdown the topic listener stream.
+  public init(
+    listen: @Sendable @escaping ([String], MQTTQoS) async throws -> Stream,
+    shutdown: @Sendable @escaping () -> Void
+  ) {
+    self._listen = listen
+    self.shutdown = shutdown
+  }
+
+  /// Create an async stream that listens for changes to the given topics.
+  ///
+  /// - Parameters:
+  ///   - topics: The topics to listen for changes to.
+  ///   - qos: The MQTTQoS for the subscription.
+  public func listen(
+    to topics: [String],
+    qos: MQTTQoS = .atLeastOnce
+  ) async throws -> Stream {
+    try await _listen(topics, qos)
+  }
+
+  /// Create an async stream that listens for changes to the given topics.
+  ///
+  /// - Parameters:
+  ///   - topics: The topics to listen for changes to.
+  ///   - qos: The MQTTQoS for the subscription.
+  public func listen(
+    _ topics: String...,
+    qos: MQTTQoS = .atLeastOnce
+  ) async throws -> Stream {
+    try await listen(to: topics, qos: qos)
+  }
+
+  /// Create the live implementation of the topic listener with the given MQTTClient.
+  ///
+  /// - Parameters:
+  ///   - client: The MQTTClient to use.
+  public static func live(client: MQTTClient) -> Self {
+    let listener = MQTTTopicListener(client: client)
+    return .init(
+      listen: { try await listener.listen($0, $1) },
+      shutdown: { listener.shutdown() }
+    )
+  }
+}
+
+extension TopicListener: TestDependencyKey {
+  public static var testValue: TopicListener { Self() }
+}
+
+public extension DependencyValues {
+  var topicListener: TopicListener {
+    get { self[TopicListener.self] }
+    set { self[TopicListener.self] = newValue }
+  }
+}
+
+// MARK: - Helpers
+
+private actor MQTTTopicListener {
+  private let client: MQTTClient
+  private let continuation: TopicListener.Stream.Continuation
+  private let name: String
+  let stream: TopicListener.Stream
+  private var shuttingDown: Bool = false
+
+  init(
+    client: MQTTClient
+  ) {
+    let (stream, continuation) = TopicListener.Stream.makeStream()
+    self.client = client
+    self.continuation = continuation
+    self.name = UUID().uuidString
+    self.stream = stream
+  }
+
+  deinit {
+    if !shuttingDown {
+      let message = """
+      Shutdown was not called on topic listener. This could lead to potential errors or
+      the stream never ending.
+
+      Please ensure that you call shutdown on the listener.
+      """
+      client.logger.warning("\(message)")
+      continuation.finish()
+    }
+    client.removePublishListener(named: name)
+    client.removeShutdownListener(named: name)
+  }
+
+  func listen(
+    _ topics: [String],
+    _ qos: MQTTQoS = .atLeastOnce
+  ) async throws(TopicListenerError) -> TopicListener.Stream {
+    var sleepTimes = 0
+
+    while !client.isActive() {
+      guard sleepTimes < 10 else {
+        throw .connectionTimeout
+      }
+      try? await Task.sleep(for: .milliseconds(100))
+      sleepTimes += 1
+    }
+
+    client.logger.trace("Client is active, begin subscribing to topics.")
+
+    let subscription = try? await client.subscribe(to: topics.map {
+      MQTTSubscribeInfo(topicFilter: $0, qos: qos)
+    })
+
+    guard subscription != nil else {
+      client.logger.error("Error subscribing to topics: \(topics)")
+      throw .failedToSubscribe
+    }
+
+    client.logger.trace("Done subscribing, begin listening to topics.")
+
+    client.addPublishListener(named: name) { result in
+      switch result {
+      case let .failure(error):
+        self.client.logger.error("Received error while listening: \(error)")
+        self.continuation.yield(.failure(.init(error)))
+      case let .success(publishInfo):
+        if topics.contains(publishInfo.topicName) {
+          self.client.logger.trace("Recieved new value for topic: \(publishInfo.topicName)")
+          self.continuation.yield(.success(publishInfo))
+        }
+      }
+    }
+
+    return stream
+  }
+
+  private func setIsShuttingDown() {
+    shuttingDown = true
+  }
+
+  nonisolated func shutdown() {
+    client.logger.trace("Closing topic listener...")
+    continuation.finish()
+    client.removePublishListener(named: name)
+    client.removeShutdownListener(named: name)
+    Task { await self.setIsShuttingDown() }
+  }
+}
+
+public enum TopicListenerError: Error {
+  case connectionTimeout
+  case failedToSubscribe
+}
+
+public struct MQTTListenResultError: Error {
+  let underlyingError: any Error
+
+  init(_ underlyingError: any Error) {
+    self.underlyingError = underlyingError
+  }
+}

Sources/TopicDependencies/TopicPublisher.swift

@@ -0,0 +1,117 @@
+import Dependencies
+import DependenciesMacros
+import MQTTNIO
+import NIO
+
+/// A dependency that is responsible for publishing values to an MQTT broker.
+///
+/// - Note: This dependency only conforms to `TestDependencyKey` because it
+/// requires an active `MQTTClient` to generate the live dependency.
+@DependencyClient
+public struct TopicPublisher: Sendable {
+
+  private var _publish: @Sendable (PublishRequest) async throws -> Void
+
+  /// Create a new topic publisher.
+  ///
+  /// - Parameters:
+  ///   -  publish: Handle the publish request.
+  public init(
+    publish: @Sendable @escaping (PublishRequest) async throws -> Void
+  ) {
+    self._publish = publish
+  }
+
+  /// Publish a new value to the given topic.
+  ///
+  /// - Parameters:
+  ///   - topicName: The topic to publish the new value to.
+  ///   - payload: The value to publish.
+  ///   - qos: The MQTTQoS.
+  ///   - retain: The retain flag.
+  public func publish(
+    to topicName: String,
+    payload: ByteBuffer,
+    qos: MQTTQoS,
+    retain: Bool = false
+  ) async throws {
+    try await _publish(.init(
+      topicName: topicName,
+      payload: payload,
+      qos: qos,
+      retain: retain
+    ))
+  }
+
+  /// Create the live topic publisher with the given `MQTTClient`.
+  ///
+  /// - Parameters:
+  ///   - client: The mqtt broker client to use.
+  public static func live(client: MQTTClient) -> Self {
+    .init(
+      publish: { request in
+        guard client.isActive() else {
+          client.logger.trace("Client is not connected, unable to publish to \(request.topicName)")
+          return
+        }
+        client.logger.trace("Begin publishing to topic: \(request.topicName)")
+        defer { client.logger.trace("Done publishing to topic: \(request.topicName)") }
+        try await client.publish(
+          to: request.topicName,
+          payload: request.payload,
+          qos: request.qos,
+          retain: request.retain
+        )
+      }
+    )
+  }
+
+  /// Represents the parameters required to publish a new value to the
+  /// MQTT broker.
+  public struct PublishRequest: Equatable, Sendable {
+
+    /// The topic to publish the new value to.
+    public let topicName: String
+
+    /// The value to publish.
+    public let payload: ByteBuffer
+
+    /// The qos of the request.
+    public let qos: MQTTQoS
+
+    /// The retain flag for the request.
+    public let retain: Bool
+
+    /// Create a new publish request.
+    ///
+    /// - Parameters:
+    ///   - topicName: The topic to publish to.
+    ///   - payload: The value to publish.
+    ///   - qos: The qos of the request.
+    ///   - retain: The retain flag of the request.
+    public init(
+      topicName: String,
+      payload: ByteBuffer,
+      qos: MQTTQoS,
+      retain: Bool
+    ) {
+      self.topicName = topicName
+      self.payload = payload
+      self.qos = qos
+      self.retain = retain
+    }
+  }
+}
+
+extension TopicPublisher: TestDependencyKey {
+  public static var testValue: TopicPublisher { Self() }
+}
+
+public extension DependencyValues {
+
+  /// A dependency that is responsible for publishing values to an MQTT broker.
+  var topicPublisher: TopicPublisher {
+    get { self[TopicPublisher.self] }
+    set { self[TopicPublisher.self] = newValue }
+  }
+}

Sources/dewPoint-controller/Application.swift

@@ -1,15 +1,19 @@
+import Dependencies
 import Foundation
 import Logging
 import Models
+import MQTTConnectionManager
 import MQTTConnectionService
 import MQTTNIO
 import NIO
 import PsychrometricClientLive
 import SensorsService
 import ServiceLifecycle
+import TopicDependencies
 
 @main
 struct Application {
+
   /// The main entry point of the application.
   static func main() async throws {
     let eventloopGroup = MultiThreadedEventLoopGroup(numberOfThreads: 1)
@@ -31,14 +35,17 @@ struct Application {
       logger: logger
     )
 
-    let mqttConnection = MQTTConnectionService(client: mqtt)
+    do {
-    let sensors = SensorsService(
+      try await withDependencies {
-      client: mqtt,
+        $0.psychrometricClient = .liveValue
-      events: { mqttConnection.events },
+        $0.topicListener = .live(client: mqtt)
-      sensors: .live
+        $0.topicPublisher = .live(client: mqtt)
-    )
+        $0.mqttConnectionManager = .live(client: mqtt, logger: logger)
+      } operation: {
+        let mqttConnection = MQTTConnectionService(logger: logger)
+        let sensors = SensorsService(sensors: .live, logger: logger)
 
-    let serviceGroup = ServiceGroup(
+        var serviceGroupConfiguration = ServiceGroupConfiguration(
           services: [
             mqttConnection,
             sensors
@@ -46,9 +53,20 @@ struct Application {
           gracefulShutdownSignals: [.sigterm, .sigint],
           logger: logger
         )
+        serviceGroupConfiguration.maximumCancellationDuration = .seconds(5)
+        serviceGroupConfiguration.maximumGracefulShutdownDuration = .seconds(10)
+
+        let serviceGroup = ServiceGroup(configuration: serviceGroupConfiguration)
 
         try await serviceGroup.run()
       }
+
+      try await mqtt.shutdown()
+      try await eventloopGroup.shutdownGracefully()
+    } catch {
+      try await eventloopGroup.shutdownGracefully()
+    }
+  }
 }
 
 // MARK: - Helpers

Tests/MQTTConnectionServiceTests/MQTTConnectionServiceTests.swift

@@ -1,7 +1,7 @@
-import Combine
 import Logging
 import Models
-@testable import MQTTConnectionService
+@testable import MQTTConnectionManager
+import MQTTConnectionService
 import MQTTNIO
 import NIO
 import ServiceLifecycle
@@ -13,22 +13,59 @@ final class MQTTConnectionServiceTests: XCTestCase {
   static let hostname = ProcessInfo.processInfo.environment["MOSQUITTO_SERVER"] ?? "localhost"
 
   static let logger: Logger = {
-    var logger = Logger(label: "AsyncClientTests")
+    var logger = Logger(label: "MQTTConnectionServiceTests")
     logger.logLevel = .trace
     return logger
   }()
 
-  func testGracefulShutdownWorks() async throws {
+//   func testGracefulShutdownWorks() async throws {
-    try await testGracefulShutdown { trigger in
+//     let client = createClient(identifier: "testGracefulShutdown")
-      let client = createClient(identifier: "testGracefulShutdown")
+//     let service = MQTTConnectionService(client: client)
-      let service = MQTTConnectionService(client: client)
+//     await service.connect()
-      try await service.run()
+//     try await Task.sleep(for: .seconds(1))
-      try await Task.sleep(for: .seconds(1))
+//     XCTAssert(client.isActive())
-      XCTAssert(client.isActive())
+//     service.shutdown()
-      trigger.triggerGracefulShutdown()
+//     XCTAssertFalse(client.isActive())
-      // try await Task.sleep(for: .seconds(2))
+//   }
-      // XCTAssertFalse(client.isActive())
+
+  func testWhatHappensIfConnectIsCalledMultipleTimes() async throws {
+    let client = createClient(identifier: "testWhatHappensIfConnectIsCalledMultipleTimes")
+    let manager = MQTTConnectionManager.live(client: client)
+    try await manager.connect()
+    try await manager.connect()
   }
+
+  // TODO: Move to integration tests.
+  func testMQTTConnectionStream() async throws {
+    let client = createClient(identifier: "testNonManagedStream")
+    let manager = MQTTConnectionManager.live(
+      client: client,
+      logger: Self.logger,
+      alwaysReconnect: false
+    )
+    let stream = MQTTConnectionStream(client: client, logger: Self.logger)
+    var events = [MQTTConnectionManager.Event]()
+
+    _ = try await manager.connect()
+
+    Task {
+      while !client.isActive() {
+        try await Task.sleep(for: .milliseconds(100))
+      }
+      try await Task.sleep(for: .milliseconds(200))
+      manager.shutdown()
+      try await client.disconnect()
+      try await Task.sleep(for: .milliseconds(200))
+      try await client.shutdown()
+      try await Task.sleep(for: .milliseconds(200))
+      stream.stop()
+    }
+
+    for await event in stream.removeDuplicates() {
+      events.append(event)
+    }
+
+    XCTAssertEqual(events, [.disconnected, .connected, .disconnected, .shuttingDown])
   }
 
   func createClient(identifier: String) -> MQTTClient {
@@ -58,65 +95,4 @@ final class MQTTConnectionServiceTests: XCTestCase {
     )
   }
 
-  func testEventStream() async throws {
-    var connection: ConnectionStream? = ConnectionStream()
-
-    let task = Task {
-      guard let events = connection?.events else { return }
-      print("before loop")
-      for await event in events {
-        print("\(event)")
-      }
-      print("after loop")
-    }
-
-    let ending = Task {
-      try await Task.sleep(for: .seconds(2))
-      connection = nil
-    }
-
-    connection?.start()
-    try await ending.value
-    task.cancel()
-  }
-
-}
-
-class ConnectionStream {
-
-  enum Event {
-    case connected
-    case disconnected
-    case shuttingDown
-  }
-
-  let events: AsyncStream<Event>
-  private let continuation: AsyncStream<Event>.Continuation
-  private var cancellable: AnyCancellable?
-
-  init() {
-    let (stream, continuation) = AsyncStream.makeStream(of: Event.self)
-    self.events = stream
-    self.continuation = continuation
-  }
-
-  deinit {
-    print("connection stream is gone.")
-    stop()
-  }
-
-  func start() {
-    cancellable = Timer.publish(every: 1.0, on: .main, in: .common)
-      .autoconnect()
-      .sink { [weak self] _ in
-        print("will send event.")
-        self?.continuation.yield(.connected)
-      }
-  }
-
-  func stop() {
-    continuation.yield(.shuttingDown)
-    cancellable = nil
-    continuation.finish()
-  }
 }

Tests/SensorsServiceTests/SensorsClientTests.swift

@@ -5,6 +5,7 @@ import MQTTNIO
 import NIO
 import PsychrometricClientLive
 @testable import SensorsService
+import TopicDependencies
 import XCTest
 
 final class SensorsClientTests: XCTestCase {
@@ -12,7 +13,7 @@ final class SensorsClientTests: XCTestCase {
   static let hostname = ProcessInfo.processInfo.environment["MOSQUITTO_SERVER"] ?? "localhost"
 
   static let logger: Logger = {
-    var logger = Logger(label: "AsyncClientTests")
+    var logger = Logger(label: "SensorsClientTests")
     logger.logLevel = .debug
     return logger
   }()
@@ -25,42 +26,28 @@ final class SensorsClientTests: XCTestCase {
     }
   }
 
-//   func createClient(identifier: String) -> SensorsClient {
+  func testWhatHappensIfClientDisconnectsWhileListening() async throws {
-//     let envVars = EnvVars(
+    let client = createClient(identifier: "testWhatHappensIfClientDisconnectsWhileListening")
-//       appEnv: .testing,
+    let listener = TopicListener.live(client: client)
-//       host: Self.hostname,
+    try await client.connect()
-//       port: "1883",
+
-//       identifier: identifier,
+    let stream = try await listener.listen("/some/topic")
-//       userName: nil,
+
-//       password: nil
+//     try await Task.sleep(for: .seconds(1))
-//     )
+//     try await client.disconnect()
-//     return .init(envVars: envVars, logger: Self.logger)
+//
-//   }
+//     try await client.connect()
-  func createClient(identifier: String) -> MQTTClient {
+//     try await Task.sleep(for: .seconds(1))
-    let envVars = EnvVars(
+    try await client.publish(
-      appEnv: .testing,
+      to: "/some/topic",
-      host: Self.hostname,
+      payload: ByteBufferAllocator().buffer(string: "Foo"),
-      port: "1883",
+      qos: .atLeastOnce,
-      identifier: identifier,
+      retain: true
-      userName: nil,
-      password: nil
-    )
-    let config = MQTTClient.Configuration(
-      version: .v3_1_1,
-      userName: envVars.userName,
-      password: envVars.password,
-      useSSL: false,
-      useWebSockets: false,
-      tlsConfiguration: nil,
-      webSocketURLPath: nil
-    )
-    return .init(
-      host: Self.hostname,
-      identifier: identifier,
-      eventLoopGroupProvider: .shared(MultiThreadedEventLoopGroup(numberOfThreads: 1)),
-      logger: Self.logger,
-      configuration: config
     )
+    try await Task.sleep(for: .seconds(1))
+
+    listener.shutdown()
+    try await client.shutdown()
   }
 
 //   func testConnectAndShutdown() async throws {
@@ -132,52 +119,52 @@ final class SensorsClientTests: XCTestCase {
 //     try await mqtt.shutdown()
 //   }
 
-  func testCapturingSensorClient() async throws {
+//   func testCapturingSensorClient() async throws {
-    class CapturedValues {
+//     class CapturedValues {
-      var values = [(value: Double, topic: String)]()
+//       var values = [(value: Double, topic: String)]()
-      var didShutdown = false
+//       var didShutdown = false
-
+//
-      init() {}
+//       init() {}
-    }
+//     }
-
+//
-    let capturedValues = CapturedValues()
+//     let capturedValues = CapturedValues()
-
+//
-    try await withDependencies {
+//     try await withDependencies {
-      $0.sensorsClient = .testing(
+//       $0.sensorsClient = .testing(
-        yielding: [
+//         yielding: [
-          (value: 76, to: "not-listening"),
+//           (value: 76, to: "not-listening"),
-          (value: 75, to: "test")
+//           (value: 75, to: "test")
-        ]
+//         ]
-      ) { value, topic in
+//       ) { value, topic in
-        capturedValues.values.append((value, topic))
+//         capturedValues.values.append((value, topic))
-      } captureShutdownEvent: {
+//       } captureShutdownEvent: {
-        capturedValues.didShutdown = $0
+//         capturedValues.didShutdown = $0
-      }
+//       }
-    } operation: {
+//     } operation: {
-      @Dependency(\.sensorsClient) var client
+//       @Dependency(\.sensorsClient) var client
-      let stream = try await client.listen(to: ["test"])
+//       let stream = try await client.listen(to: ["test"])
-
+//
-      for await value in stream {
+//       for await result in stream {
-        var buffer = value.payload
+//         var buffer = result.buffer
-        guard let double = Double(buffer: &buffer) else {
+//         guard let double = Double(buffer: &buffer) else {
-          XCTFail("Failed to decode double")
+//           XCTFail("Failed to decode double")
-          return
+//           return
-        }
+//         }
-
+//
-        XCTAssertEqual(double, 75)
+//         XCTAssertEqual(double, 75)
-        XCTAssertEqual(value.topicName, "test")
+//         XCTAssertEqual(result.topic, "test")
-        try await client.publish(26, to: "publish")
+//         try await client.publish(26, to: "publish")
-        try await Task.sleep(for: .milliseconds(100))
+//         try await Task.sleep(for: .milliseconds(100))
-        client.shutdown()
+//         client.shutdown()
-      }
+//       }
-
+//
-      XCTAssertEqual(capturedValues.values.count, 1)
+//       XCTAssertEqual(capturedValues.values.count, 1)
-      XCTAssertEqual(capturedValues.values.first?.value, 26)
+//       XCTAssertEqual(capturedValues.values.first?.value, 26)
-      XCTAssertEqual(capturedValues.values.first?.topic, "publish")
+//       XCTAssertEqual(capturedValues.values.first?.topic, "publish")
-      XCTAssertTrue(capturedValues.didShutdown)
+//       XCTAssertTrue(capturedValues.didShutdown)
-    }
+//     }
-  }
+//   }
-
+//
 //   func testSensorCapturesPublishedState() async throws {
 //     let client = createClient(identifier: "testSensorCapturesPublishedState")
 //     let mqtt = client.client
@@ -234,10 +221,47 @@ final class SensorsClientTests: XCTestCase {
 //
 //     await client.shutdown()
 //   }
+
+  func createClient(identifier: String) -> MQTTClient {
+    let envVars = EnvVars(
+      appEnv: .testing,
+      host: Self.hostname,
+      port: "1883",
+      identifier: identifier,
+      userName: nil,
+      password: nil
+    )
+    let config = MQTTClient.Configuration(
+      version: .v3_1_1,
+      userName: envVars.userName,
+      password: envVars.password,
+      useSSL: false,
+      useWebSockets: false,
+      tlsConfiguration: nil,
+      webSocketURLPath: nil
+    )
+    return .init(
+      host: Self.hostname,
+      identifier: identifier,
+      eventLoopGroupProvider: .shared(MultiThreadedEventLoopGroup(numberOfThreads: 1)),
+      logger: Self.logger,
+      configuration: config
+    )
+  }
 }
 
 // MARK: Helpers for tests.
 
+extension AsyncStream {
+  func first() async -> Element {
+    var first: Element
+    for await value in self {
+      first = value
+    }
+    return first
+  }
+}
+
 class PublishInfoContainer {
   private(set) var info: [MQTTPublishInfo]
   private var topicFilters: [String]?
@@ -258,41 +282,35 @@ class PublishInfoContainer {
   }
 }
 
-extension SensorsClient {
+// extension SensorsClient {
-
+//
-  static func testing(
+//   static func testing(
-    yielding: [(value: Double, to: String)],
+//     yielding: [(value: Double, to: String)],
-    capturePublishedValues: @escaping (Double, String) -> Void,
+//     capturePublishedValues: @escaping (Double, String) -> Void,
-    captureShutdownEvent: @escaping (Bool) -> Void
+//     captureShutdownEvent: @escaping (Bool) -> Void
-  ) -> Self {
+//   ) -> Self {
-    let (stream, continuation) = AsyncStream.makeStream(of: MQTTPublishInfo.self)
+//     let (stream, continuation) = AsyncStream.makeStream(of: PublishInfo.self)
-    let logger = Logger(label: "\(Self.self).testing")
+//     let logger = Logger(label: "\(Self.self).testing")
-
+//
-    return .init(
+//     return .init(
-      listen: { topics in
+//       listen: { topics in
-        for (value, topic) in yielding where topics.contains(topic) {
+//         for (value, topic) in yielding where topics.contains(topic) {
-          continuation.yield(
+//           continuation.yield(
-            MQTTPublishInfo(
+//             (buffer: ByteBuffer(string: "\(value)"), topic: topic)
-              qos: .atLeastOnce,
+//           )
-              retain: true,
+//         }
-              topicName: topic,
+//         return stream
-              payload: ByteBuffer(string: "\(value)"),
+//       },
-              properties: MQTTProperties()
+//       logger: logger,
-            )
+//       publish: { value, topic in
-          )
+//         capturePublishedValues(value, topic)
-        }
+//       },
-        return stream
+//       shutdown: {
-      },
+//         captureShutdownEvent(true)
-      logger: logger,
+//         continuation.finish()
-      publish: { value, topic in
+//       }
-        capturePublishedValues(value, topic)
+//     )
-      },
+//   }
-      shutdown: {
+// }
-        captureShutdownEvent(true)
-        continuation.finish()
-      }
-    )
-  }
-}
 
 struct TopicNotFoundError: Error {}

Tests/dewPoint-controllerTests/dewPoint_controllerTests.swift

@@ -1,47 +0,0 @@
-import XCTest
-import class Foundation.Bundle
-
-//final class dewPoint_controllerTests: XCTestCase {
-//    func testExample() throws {
-//        // This is an example of a functional test case.
-//        // Use XCTAssert and related functions to verify your tests produce the correct
-//        // results.
-//
-//        // Some of the APIs that we use below are available in macOS 10.13 and above.
-//        guard #available(macOS 10.13, *) else {
-//            return
-//        }
-//
-//        // Mac Catalyst won't have `Process`, but it is supported for executables.
-//        #if !targetEnvironment(macCatalyst)
-//
-//        let fooBinary = productsDirectory.appendingPathComponent("dewPoint-controller")
-//
-//        let process = Process()
-//        process.executableURL = fooBinary
-//
-//        let pipe = Pipe()
-//        process.standardOutput = pipe
-//
-//        try process.run()
-//        process.waitUntilExit()
-//
-//        let data = pipe.fileHandleForReading.readDataToEndOfFile()
-//        let output = String(data: data, encoding: .utf8)
-//
-//        XCTAssertEqual(output, "Hello, world!\n")
-//        #endif
-//    }
-//
-//    /// Returns path to the built products directory.
-//    var productsDirectory: URL {
-//      #if os(macOS)
-//        for bundle in Bundle.allBundles where bundle.bundlePath.hasSuffix(".xctest") {
-//            return bundle.bundleURL.deletingLastPathComponent()
-//        }
-//        fatalError("couldn't find the products directory")
-//      #else
-//        return Bundle.main.bundleURL
-//      #endif
-//    }
-//}

docker-compose.yaml

@@ -14,7 +14,7 @@ services:
     depends_on:
       - mosquitto
     environment:
-      - MOSQUITTO_SERVER=mosquitto
+      - MQTT_HOST=mosquitto
 
   test:
     build: