feat: Add unit tests and fakes for Crestron environment and data store

- Introduced `FakeCrestronEnvironment` and `FakeEthernetHelper` for testing purposes.
- Implemented `InMemoryCrestronDataStore` to facilitate unit tests for data storage.
- Created `DebugServiceTests` to validate the behavior of debug-related services.
- Added project files for unit tests targeting .NET 9.0 with necessary dependencies.
- Developed production adapters (`CrestronConsoleAdapter`, `CrestronDataStoreAdapter`, `CrestronEnvironmentAdapter`, `CrestronEthernetAdapter`) to interface with the Crestron SDK.
- Updated `Debug` class to utilize injected service abstractions instead of direct SDK calls.
- Enhanced `ControlSystem` initialization to register service adapters before usage.

src/PepperDash.Core.Abstractions/DebugServiceRegistration.cs

@@ -0,0 +1,36 @@
+namespace PepperDash.Core.Abstractions;
+
+/// <summary>
+/// Allows pre-registration of Crestron service implementations before the <c>Debug</c>
+/// static class initialises. Call <see cref="Register"/> from the composition root
+/// (e.g. ControlSystem constructor) <em>before</em> any code touches <c>Debug.*</c>.
+/// Test projects should call it with no-op / in-memory implementations so that the
+/// <c>Debug</c> static constructor never tries to reach the real Crestron SDK.
+/// </summary>
+public static class DebugServiceRegistration
+{
+    /// <summary>Gets the registered environment abstraction, or <c>null</c> if not registered.</summary>
+    public static ICrestronEnvironment? Environment { get; private set; }
+
+    /// <summary>Gets the registered console abstraction, or <c>null</c> if not registered.</summary>
+    public static ICrestronConsole? Console { get; private set; }
+
+    /// <summary>Gets the registered data-store abstraction, or <c>null</c> if not registered.</summary>
+    public static ICrestronDataStore? DataStore { get; private set; }
+
+    /// <summary>
+    /// Registers the service implementations that <c>Debug</c> will use when its
+    /// static constructor runs. Any parameter may be <c>null</c> to leave the
+    /// corresponding service unregistered (the <c>Debug</c> class will skip that
+    /// capability gracefully).
+    /// </summary>
+    public static void Register(
+        ICrestronEnvironment? environment,
+        ICrestronConsole? console,
+        ICrestronDataStore? dataStore)
+    {
+        Environment = environment;
+        Console = console;
+        DataStore = dataStore;
+    }
+}

src/PepperDash.Core.Abstractions/Enums.cs

@@ -0,0 +1,100 @@
+namespace PepperDash.Core.Abstractions;
+
+/// <summary>
+/// Mirrors Crestron's <c>eDevicePlatform</c> without requiring the Crestron SDK.
+/// </summary>
+public enum DevicePlatform
+{
+    /// <summary>Hardware appliance (e.g. CP4, MC4).</summary>
+    Appliance,
+    /// <summary>Crestron Virtual Control / server runtime.</summary>
+    Server,
+}
+
+/// <summary>
+/// Mirrors Crestron's <c>eRuntimeEnvironment</c>.
+/// </summary>
+public enum RuntimeEnvironment
+{
+    /// <summary>SimplSharpPro program slot (hardware 4-series).</summary>
+    SimplSharpPro,
+    /// <summary>SimplSharp (older 3-series or server environments).</summary>
+    SimplSharp,
+    /// <summary>Any other environment — check for completeness.</summary>
+    Other,
+}
+
+/// <summary>
+/// Mirrors Crestron's <c>ConsoleAccessLevelEnum</c>.
+/// </summary>
+public enum ConsoleAccessLevel
+{
+    AccessAdministrator = 0,
+    AccessOperator = 1,
+    AccessProgrammer = 2,
+}
+
+/// <summary>
+/// Mirrors Crestron's <c>eProgramStatusEventType</c>.
+/// </summary>
+public enum ProgramStatusEventType
+{
+    Starting,
+    Stopping,
+    Paused,
+    Resumed,
+}
+
+/// <summary>
+/// Mirrors the event type used by Crestron's <c>EthernetEventArgs</c>.
+/// </summary>
+public enum EthernetEventType
+{
+    LinkDown = 0,
+    LinkUp = 1,
+}
+
+/// <summary>
+/// Event args for Crestron ethernet link events.
+/// </summary>
+public class PepperDashEthernetEventArgs : EventArgs
+{
+    public EthernetEventType EthernetEventType { get; }
+    public short EthernetAdapter { get; }
+
+    public PepperDashEthernetEventArgs(EthernetEventType eventType, short adapter)
+    {
+        EthernetEventType = eventType;
+        EthernetAdapter = adapter;
+    }
+}
+
+/// <summary>
+/// Mirrors the set of <c>CrestronEthernetHelper.ETHERNET_PARAMETER_TO_GET</c> values
+/// used across this codebase — does not aim to be exhaustive.
+/// </summary>
+public enum EthernetParameterType
+{
+    GetCurrentIpAddress,
+    GetHostname,
+    GetDomainName,
+    GetLinkStatus,
+    GetCurrentDhcpState,
+    GetCurrentIpMask,
+    GetCurrentRouter,
+    GetMacAddress,
+    GetDnsServer,
+}
+
+/// <summary>
+/// Mirrors Crestron's <c>SocketStatus</c> without requiring the Crestron SDK.
+/// </summary>
+public enum PepperDashSocketStatus
+{
+    SocketNotConnected = 0,
+    SocketConnected = 2,
+    SocketConnectionInProgress = 6,
+    SocketConnectFailed = 11,
+    SocketDisconnecting = 12,
+    SocketBrokenRemotely = 7,
+}

src/PepperDash.Core.Abstractions/ICrestronConsole.cs

@@ -0,0 +1,32 @@
+namespace PepperDash.Core.Abstractions;
+
+/// <summary>
+/// Abstracts <c>Crestron.SimplSharp.CrestronConsole</c> to allow unit testing
+/// without the Crestron SDK.
+/// </summary>
+public interface ICrestronConsole
+{
+    /// <summary>Prints a line to the Crestron console/telnet output.</summary>
+    void PrintLine(string message);
+
+    /// <summary>Prints text (without newline) to the Crestron console/telnet output.</summary>
+    void Print(string message);
+
+    /// <summary>
+    /// Sends a response string to the console for the currently-executing console command.
+    /// </summary>
+    void ConsoleCommandResponse(string message);
+
+    /// <summary>
+    /// Registers a new command with the Crestron console.
+    /// </summary>
+    /// <param name="callback">Handler invoked when the command is typed.</param>
+    /// <param name="command">Command name (no spaces).</param>
+    /// <param name="helpText">Help text shown by the Crestron console.</param>
+    /// <param name="accessLevel">Minimum access level required to run the command.</param>
+    void AddNewConsoleCommand(
+        Action<string> callback,
+        string command,
+        string helpText,
+        ConsoleAccessLevel accessLevel);
+}

src/PepperDash.Core.Abstractions/ICrestronDataStore.cs

@@ -0,0 +1,31 @@
+namespace PepperDash.Core.Abstractions;
+
+/// <summary>
+/// Abstracts <c>Crestron.SimplSharp.CrestronDataStore.CrestronDataStoreStatic</c>
+/// to allow unit testing without the Crestron SDK.
+/// </summary>
+public interface ICrestronDataStore
+{
+    /// <summary>Initialises the data store. Must be called once before any other operation.</summary>
+    void InitStore();
+
+    /// <summary>Reads an integer value from the local (program-slot) store.</summary>
+    /// <returns><c>true</c> if the value was found and read successfully.</returns>
+    bool TryGetLocalInt(string key, out int value);
+
+    /// <summary>Writes an integer value to the local (program-slot) store.</summary>
+    /// <returns><c>true</c> on success.</returns>
+    bool SetLocalInt(string key, int value);
+
+    /// <summary>Writes an unsigned integer value to the local (program-slot) store.</summary>
+    /// <returns><c>true</c> on success.</returns>
+    bool SetLocalUint(string key, uint value);
+
+    /// <summary>Reads a boolean value from the local (program-slot) store.</summary>
+    /// <returns><c>true</c> if the value was found and read successfully.</returns>
+    bool TryGetLocalBool(string key, out bool value);
+
+    /// <summary>Writes a boolean value to the local (program-slot) store.</summary>
+    /// <returns><c>true</c> on success.</returns>
+    bool SetLocalBool(string key, bool value);
+}

src/PepperDash.Core.Abstractions/ICrestronEnvironment.cs

@@ -0,0 +1,45 @@
+namespace PepperDash.Core.Abstractions;
+
+/// <summary>
+/// Abstracts <c>Crestron.SimplSharp.CrestronEnvironment</c> to allow unit testing
+/// without the Crestron SDK.
+/// </summary>
+public interface ICrestronEnvironment
+{
+    /// <summary>Gets the platform the program is executing on.</summary>
+    DevicePlatform DevicePlatform { get; }
+
+    /// <summary>Gets the current runtime environment.</summary>
+    RuntimeEnvironment RuntimeEnvironment { get; }
+
+    /// <summary>Gets the platform-appropriate newline string.</summary>
+    string NewLine { get; }
+
+    /// <summary>Gets the application number (program slot).</summary>
+    uint ApplicationNumber { get; }
+
+    /// <summary>Gets the room ID (used in Crestron Virtual Control / server environments).</summary>
+    uint RoomId { get; }
+
+    /// <summary>Raised when program status changes (starting, stopping, etc.).</summary>
+    event EventHandler<ProgramStatusEventArgs> ProgramStatusChanged;
+
+    /// <summary>Raised when the ethernet link changes state.</summary>
+    event EventHandler<PepperDashEthernetEventArgs> EthernetEventReceived;
+
+    /// <summary>Gets the application root directory path.</summary>
+    string GetApplicationRootDirectory();
+}
+
+/// <summary>
+/// Event args for <see cref="ICrestronEnvironment.ProgramStatusChanged"/>.
+/// </summary>
+public class ProgramStatusEventArgs : EventArgs
+{
+    public ProgramStatusEventType EventType { get; }
+
+    public ProgramStatusEventArgs(ProgramStatusEventType eventType)
+    {
+        EventType = eventType;
+    }
+}

src/PepperDash.Core.Abstractions/IEthernetHelper.cs

@@ -0,0 +1,16 @@
+namespace PepperDash.Core.Abstractions;
+
+/// <summary>
+/// Abstracts <c>Crestron.SimplSharp.CrestronEthernetHelper</c> to allow unit testing
+/// without the Crestron SDK.
+/// </summary>
+public interface IEthernetHelper
+{
+    /// <summary>
+    /// Returns a network parameter string for the specified adapter.
+    /// </summary>
+    /// <param name="parameter">The parameter to retrieve.</param>
+    /// <param name="ethernetAdapterId">Ethernet adapter index (0 = LAN A).</param>
+    /// <returns>String value of the requested parameter.</returns>
+    string GetEthernetParameter(EthernetParameterType parameter, short ethernetAdapterId);
+}

src/PepperDash.Core.Abstractions/PepperDash.Core.Abstractions.csproj

@@ -0,0 +1,19 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <RootNamespace>PepperDash.Core.Abstractions</RootNamespace>
+    <AssemblyName>PepperDash.Core.Abstractions</AssemblyName>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Deterministic>true</Deterministic>
+    <NeutralLanguage>en</NeutralLanguage>
+    <Title>PepperDash Core Abstractions</Title>
+    <Company>PepperDash Technologies</Company>
+    <RepositoryType>git</RepositoryType>
+    <RepositoryUrl>https://github.com/PepperDash/PepperDashCore</RepositoryUrl>
+    <NullableContextOptions>enable</NullableContextOptions>
+    <IncludeSourceRevisionInInformationalVersion>false</IncludeSourceRevisionInInformationalVersion>
+    <InformationalVersion>$(Version)</InformationalVersion>
+    <GenerateAssemblyInfo>true</GenerateAssemblyInfo>
+    <!-- No Crestron SDK reference — this project must remain hardware-agnostic so test projects can reference it -->
+  </PropertyGroup>
+</Project>