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.Tests/Fakes/CrestronConsoleFakes.cs

@@ -0,0 +1,38 @@
+using PepperDash.Core.Abstractions;
+
+namespace PepperDash.Core.Tests.Fakes;
+
+/// <summary>
+/// No-op ICrestronConsole that captures output for test assertions.
+/// </summary>
+public class CapturingCrestronConsole : ICrestronConsole
+{
+    public List<string> Lines { get; } = new();
+    public List<string> CommandResponses { get; } = new();
+    public List<(string Command, string HelpText)> RegisteredCommands { get; } = new();
+
+    public void PrintLine(string message) => Lines.Add(message);
+    public void Print(string message) => Lines.Add(message);
+    public void ConsoleCommandResponse(string message) => CommandResponses.Add(message);
+
+    public void AddNewConsoleCommand(
+        Action<string> callback,
+        string command,
+        string helpText,
+        ConsoleAccessLevel accessLevel)
+    {
+        RegisteredCommands.Add((command, helpText));
+    }
+}
+
+/// <summary>
+/// Minimal no-op ICrestronConsole that discards all output. Useful when you only
+/// care about the system under test and not what it logs.
+/// </summary>
+public class NoOpCrestronConsole : ICrestronConsole
+{
+    public void PrintLine(string message) { }
+    public void Print(string message) { }
+    public void ConsoleCommandResponse(string message) { }
+    public void AddNewConsoleCommand(Action<string> _, string __, string ___, ConsoleAccessLevel ____) { }
+}

src/PepperDash.Core.Tests/Fakes/CrestronEnvironmentFakes.cs

@@ -0,0 +1,46 @@
+using PepperDash.Core.Abstractions;
+
+namespace PepperDash.Core.Tests.Fakes;
+
+/// <summary>
+/// Configurable ICrestronEnvironment for unit tests.
+/// Defaults: Appliance / SimplSharpPro / ApplicationNumber=1.
+/// </summary>
+public class FakeCrestronEnvironment : ICrestronEnvironment
+{
+    public DevicePlatform DevicePlatform { get; set; } = DevicePlatform.Appliance;
+    public RuntimeEnvironment RuntimeEnvironment { get; set; } = RuntimeEnvironment.SimplSharpPro;
+    public string NewLine { get; set; } = "\r\n";
+    public uint ApplicationNumber { get; set; } = 1;
+    public uint RoomId { get; set; } = 0;
+
+    public event EventHandler<ProgramStatusEventArgs>? ProgramStatusChanged;
+    public event EventHandler<PepperDashEthernetEventArgs>? EthernetEventReceived;
+
+    public string GetApplicationRootDirectory() => System.IO.Path.GetTempPath();
+
+    /// <summary>Simulates a program status event for tests.</summary>
+    public void RaiseProgramStatus(ProgramStatusEventType type) =>
+        ProgramStatusChanged?.Invoke(this, new ProgramStatusEventArgs(type));
+
+    /// <summary>Simulates an ethernet event for tests.</summary>
+    public void RaiseEthernetEvent(EthernetEventType type, short adapter = 0) =>
+        EthernetEventReceived?.Invoke(this, new PepperDashEthernetEventArgs(type, adapter));
+}
+
+/// <summary>
+/// No-op IEthernetHelper that returns configurable values.
+/// </summary>
+public class FakeEthernetHelper : IEthernetHelper
+{
+    private readonly Dictionary<EthernetParameterType, string> _values = new();
+
+    public FakeEthernetHelper Seed(EthernetParameterType param, string value)
+    {
+        _values[param] = value;
+        return this;
+    }
+
+    public string GetEthernetParameter(EthernetParameterType parameter, short ethernetAdapterId) =>
+        _values.TryGetValue(parameter, out var v) ? v : string.Empty;
+}

src/PepperDash.Core.Tests/Fakes/InMemoryCrestronDataStore.cs

@@ -0,0 +1,59 @@
+using PepperDash.Core.Abstractions;
+
+namespace PepperDash.Core.Tests.Fakes;
+
+/// <summary>
+/// In-memory ICrestronDataStore backed by a dictionary.
+/// Use in unit tests to verify that keys are read from and written to the store correctly.
+/// </summary>
+public class InMemoryCrestronDataStore : ICrestronDataStore
+{
+    private readonly Dictionary<string, object> _store = new();
+
+    public bool Initialized { get; private set; }
+
+    public void InitStore() => Initialized = true;
+
+    public bool TryGetLocalInt(string key, out int value)
+    {
+        if (_store.TryGetValue(key, out var raw) && raw is int i)
+        {
+            value = i;
+            return true;
+        }
+        value = 0;
+        return false;
+    }
+
+    public bool SetLocalInt(string key, int value)
+    {
+        _store[key] = value;
+        return true;
+    }
+
+    public bool SetLocalUint(string key, uint value)
+    {
+        _store[key] = (int)value;
+        return true;
+    }
+
+    public bool TryGetLocalBool(string key, out bool value)
+    {
+        if (_store.TryGetValue(key, out var raw) && raw is bool b)
+        {
+            value = b;
+            return true;
+        }
+        value = false;
+        return false;
+    }
+
+    public bool SetLocalBool(string key, bool value)
+    {
+        _store[key] = value;
+        return true;
+    }
+
+    /// <summary>Seeds a key for testing read paths.</summary>
+    public void Seed(string key, object value) => _store[key] = value;
+}

src/PepperDash.Core.Tests/Logging/DebugServiceTests.cs

@@ -0,0 +1,171 @@
+using FluentAssertions;
+using PepperDash.Core.Abstractions;
+using PepperDash.Core.Tests.Fakes;
+using Xunit;
+
+namespace PepperDash.Core.Tests.Logging;
+
+/// <summary>
+/// Tests for Debug-related service interfaces and implementations.
+/// These tests verify the behaviour of the abstractions in isolation (no Crestron SDK required).
+/// </summary>
+public class DebugServiceTests
+{
+    // -----------------------------------------------------------------------
+    // ICrestronDataStore — InMemoryCrestronDataStore
+    // -----------------------------------------------------------------------
+
+    [Fact]
+    public void DataStore_InitStore_SetsInitializedFlag()
+    {
+        var store = new InMemoryCrestronDataStore();
+        store.Initialized.Should().BeFalse("not yet initialized");
+
+        store.InitStore();
+
+        store.Initialized.Should().BeTrue();
+    }
+
+    [Fact]
+    public void DataStore_SetAndGetLocalInt_RoundTrips()
+    {
+        var store = new InMemoryCrestronDataStore();
+
+        store.SetLocalInt("MyKey", 42).Should().BeTrue();
+        store.TryGetLocalInt("MyKey", out var value).Should().BeTrue();
+        value.Should().Be(42);
+    }
+
+    [Fact]
+    public void DataStore_TryGetLocalInt_ReturnsFalse_WhenKeyAbsent()
+    {
+        var store = new InMemoryCrestronDataStore();
+
+        store.TryGetLocalInt("Missing", out var value).Should().BeFalse();
+        value.Should().Be(0);
+    }
+
+    [Fact]
+    public void DataStore_SetAndGetLocalBool_RoundTrips()
+    {
+        var store = new InMemoryCrestronDataStore();
+
+        store.SetLocalBool("FlagKey", true).Should().BeTrue();
+        store.TryGetLocalBool("FlagKey", out var value).Should().BeTrue();
+        value.Should().BeTrue();
+    }
+
+    [Fact]
+    public void DataStore_TryGetLocalBool_ReturnsFalse_WhenKeyAbsent()
+    {
+        var store = new InMemoryCrestronDataStore();
+
+        store.TryGetLocalBool("Missing", out var value).Should().BeFalse();
+        value.Should().BeFalse();
+    }
+
+    [Fact]
+    public void DataStore_SetLocalUint_CanBeReadBackAsInt()
+    {
+        var store = new InMemoryCrestronDataStore();
+
+        store.SetLocalUint("UintKey", 3u).Should().BeTrue();
+        store.TryGetLocalInt("UintKey", out var value).Should().BeTrue();
+        value.Should().Be(3);
+    }
+
+    [Fact]
+    public void DataStore_Seed_AllowsTestSetupOfReadPaths()
+    {
+        var store = new InMemoryCrestronDataStore();
+        store.Seed("MyLevel", 2);
+
+        store.TryGetLocalInt("MyLevel", out var level).Should().BeTrue();
+        level.Should().Be(2);
+    }
+
+    // -----------------------------------------------------------------------
+    // DebugServiceRegistration
+    // -----------------------------------------------------------------------
+
+    [Fact]
+    public void ServiceRegistration_Register_StoresAllThreeServices()
+    {
+        var env = new FakeCrestronEnvironment();
+        var console = new NoOpCrestronConsole();
+        var store = new InMemoryCrestronDataStore();
+
+        DebugServiceRegistration.Register(env, console, store);
+
+        DebugServiceRegistration.Environment.Should().BeSameAs(env);
+        DebugServiceRegistration.Console.Should().BeSameAs(console);
+        DebugServiceRegistration.DataStore.Should().BeSameAs(store);
+    }
+
+    [Fact]
+    public void ServiceRegistration_Register_AcceptsNullsWithoutThrowing()
+    {
+        var act = () => DebugServiceRegistration.Register(null, null, null);
+        act.Should().NotThrow();
+    }
+
+    // -----------------------------------------------------------------------
+    // ICrestronEnvironment — FakeCrestronEnvironment
+    // -----------------------------------------------------------------------
+
+    [Fact]
+    public void FakeEnvironment_DefaultsToAppliance()
+    {
+        var env = new FakeCrestronEnvironment();
+        env.DevicePlatform.Should().Be(DevicePlatform.Appliance);
+    }
+
+    [Fact]
+    public void FakeEnvironment_RaiseProgramStatus_FiresEvent()
+    {
+        var env = new FakeCrestronEnvironment();
+        ProgramStatusEventType? received = null;
+        env.ProgramStatusChanged += (_, e) => received = e.EventType;
+
+        env.RaiseProgramStatus(ProgramStatusEventType.Stopping);
+
+        received.Should().Be(ProgramStatusEventType.Stopping);
+    }
+
+    [Fact]
+    public void FakeEnvironment_RaiseEthernetEvent_FiresEvent()
+    {
+        var env = new FakeCrestronEnvironment();
+        EthernetEventType? received = null;
+        env.EthernetEventReceived += (_, e) => received = e.EthernetEventType;
+
+        env.RaiseEthernetEvent(EthernetEventType.LinkUp, adapter: 0);
+
+        received.Should().Be(EthernetEventType.LinkUp);
+    }
+
+    // -----------------------------------------------------------------------
+    // ICrestronConsole — CapturingCrestronConsole
+    // -----------------------------------------------------------------------
+
+    [Fact]
+    public void CapturingConsole_PrintLine_CapturesMessage()
+    {
+        var console = new CapturingCrestronConsole();
+
+        console.PrintLine("hello world");
+
+        console.Lines.Should().ContainSingle().Which.Should().Be("hello world");
+    }
+
+    [Fact]
+    public void CapturingConsole_AddNewConsoleCommand_RecordsCommandName()
+    {
+        var console = new CapturingCrestronConsole();
+
+        console.AddNewConsoleCommand(_ => { }, "appdebug", "Sets debug level", ConsoleAccessLevel.AccessOperator);
+
+        console.RegisteredCommands.Should().ContainSingle()
+            .Which.Command.Should().Be("appdebug");
+    }
+}

src/PepperDash.Core.Tests/PepperDash.Core.Tests.csproj

@@ -0,0 +1,25 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net9.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <IsPackable>false</IsPackable>
+    <GeneratePackageOnBuild>false</GeneratePackageOnBuild>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
+    <PackageReference Include="xunit" Version="2.9.3" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="NSubstitute" Version="5.3.0" />
+    <PackageReference Include="FluentAssertions" Version="7.0.0" />
+  </ItemGroup>
+
+  <!-- Reference the Abstractions project only — no Crestron SDK dependency -->
+  <ItemGroup>
+    <ProjectReference Include="..\PepperDash.Core.Abstractions\PepperDash.Core.Abstractions.csproj" />
+  </ItemGroup>
+</Project>