feat: make DiscordChannelAdapter testable and add unit tests

CHANGELOG.md

@@ -20,6 +20,7 @@ Please ADD ALL Changes to the UNRELEASED SECTION and not a specific release
 - SnsMessage: Token property was never populated from the constructor argument
 - Added null guards for botMessageChannel and botReleaseMessageChannel parameters in BotService constructor
 - Pass ILogger to HealthCheckClient.ExecuteAsync to match new API in Credfeto.Docker.HealthCheck.Http.Client 0.0.72.928
+- Made DiscordChannelAdapter testable by accepting ITextChannel instead of the sealed SocketTextChannel, and added unit tests
 ### Changed
 - Dependencies - Updated NSubstitute.Analyzers.CSharp to 1.0.17
 - Switched to use minimal APIs

src/BuildBot.Discord.Tests/BuildBot.Discord.Tests.csproj

@@ -70,4 +70,4 @@
     <PackageReference Include="ToStringWithoutOverrideAnalyzer" Version="0.6.0" PrivateAssets="All" ExcludeAssets="runtime" />
     <PackageReference Include="xunit.analyzers" Version="1.27.0" PrivateAssets="All" ExcludeAssets="runtime" />
   </ItemGroup>
-</Project>
+</Project>

src/BuildBot.Discord.Tests/Services/DiscordChannelAdapterTests.cs

@@ -0,0 +1,75 @@
+using System;
+using System.Threading.Tasks;
+using BuildBot.Discord.Services;
+using Discord;
+using FunFair.Test.Common;
+using NSubstitute;
+using Xunit;
+
+namespace BuildBot.Discord.Tests.Services;
+
+public sealed class DiscordChannelAdapterTests : TestBase
+{
+    [Fact]
+    public void Name_ReturnsChannelName()
+    {
+        ITextChannel channel = GetSubstitute<ITextChannel>();
+        channel.Name.Returns("test-channel");
+
+        DiscordChannelAdapter adapter = new(channel);
+
+        Assert.Equal(expected: "test-channel", actual: adapter.Name);
+    }
+
+    [Fact]
+    public void EnterTypingState_ReturnsTypingStateFromChannel()
+    {
+        ITextChannel channel = GetSubstitute<ITextChannel>();
+        IDisposable typingState = GetSubstitute<IDisposable>();
+        channel.EnterTypingState(Arg.Any<RequestOptions>()).Returns(typingState);
+
+        DiscordChannelAdapter adapter = new(channel);
+
+        IDisposable result = adapter.EnterTypingState();
+
+        Assert.Same(expected: typingState, actual: result);
+    }
+
+    [Fact]
+    public async Task SendMessageAsync_ReturnsChannelNameAndCleanContent()
+    {
+        ITextChannel channel = GetSubstitute<ITextChannel>();
+        IUserMessage message = GetSubstitute<IUserMessage>();
+
+        channel.Name.Returns("sent-channel");
+
+        // In production CleanContent is always "" because the adapter sends text: string.Empty (embed-only).
+        message.CleanContent.Returns("clean content");
+
+        channel.SendMessageAsync(text: string.Empty, embed: default).ReturnsForAnyArgs(Task.FromResult(message));
+
+        DiscordChannelAdapter adapter = new(channel);
+
+        Embed embed = new EmbedBuilder().Build();
+        (string sentToChannel, string messageContent) = await adapter.SendMessageAsync(embed);
+
+        Assert.Equal(expected: "sent-channel", actual: sentToChannel);
+        Assert.Equal(expected: "clean content", actual: messageContent);
+
+        await channel
+            .Received(1)
+            .SendMessageAsync(
+                text: string.Empty,
+                isTTS: Arg.Any<bool>(),
+                embed: embed,
+                options: Arg.Any<RequestOptions>(),
+                allowedMentions: Arg.Any<AllowedMentions>(),
+                messageReference: Arg.Any<MessageReference>(),
+                components: Arg.Any<MessageComponent>(),
+                stickers: Arg.Any<ISticker[]>(),
+                embeds: Arg.Any<Embed[]>(),
+                flags: Arg.Any<MessageFlags>(),
+                poll: Arg.Any<PollProperties>()
+            );
+    }
+}

src/BuildBot.Discord/Services/DiscordChannelAdapter.cs

@@ -1,18 +1,16 @@
 using System;
 using System.Threading.Tasks;
 using Discord;
-using Discord.Rest;
-using Discord.WebSocket;
 
 namespace BuildBot.Discord.Services;
 
-internal sealed class DiscordChannelAdapter : IDiscordChannel
+public sealed class DiscordChannelAdapter : IDiscordChannel
 {
-    private readonly SocketTextChannel _channel;
+    private readonly ITextChannel _channel;
 
-    public DiscordChannelAdapter(SocketTextChannel channel)
+    public DiscordChannelAdapter(ITextChannel channel)
     {
-        this._channel = channel;
+        this._channel = channel ?? throw new ArgumentNullException(nameof(channel));
     }
 
     public string Name => this._channel.Name;
@@ -24,8 +22,8 @@ public IDisposable EnterTypingState()
 
     public async Task<(string SentToChannel, string MessageContent)> SendMessageAsync(Embed embed)
     {
-        RestUserMessage msg = await this._channel.SendMessageAsync(text: string.Empty, embed: embed);
+        IUserMessage msg = await this._channel.SendMessageAsync(text: string.Empty, embed: embed);
 
-        return (msg.Channel.Name, msg.CleanContent);
+        return (this._channel.Name, msg.CleanContent);
     }
 }