From 0439469f248cafdb60fce91ba79ccfcd1f7068e2 Mon Sep 17 00:00:00 2001
From: Mark Ridgwell <273118822+dnyw4l3n13@users.noreply.github.com>
Date: Mon, 22 Jun 2026 11:06:34 +0000
Subject: [PATCH 1/2] test(discord): Add null-guard branch coverage for
 BotService constructor

Adds a reflection-based test to cover the null-bot argument guard in
BotService, bringing BotService to 100% line and branch coverage.
The null! operator cannot be used directly due to the NX0002 analyser
rule, so the constructor is invoked via reflection.

Prompt: Work on issue #356 in funfair-tech/BuildBot.
Closes #356
---
 CHANGELOG.md                                      |  1 +
 .../Services/BotServiceTests.cs                   | 15 +++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 54f60b33..9b022b13 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ Please ADD ALL Changes to the UNRELEASED SECTION and not a specific release
 - BuildBot.Json.Tests: new test project covering BuildBot.Json at 100% line and branch coverage
 - BuildBot.ServiceModel.Tests: Added test coverage for all types in BuildBot.ServiceModel
 - BuildBot.Discord.Tests: Added unit tests to increase code coverage to 100%
+- BotService null-guard branch coverage test
 ### Fixed
 - Suppress known Scriban 6.2.0 vulnerabilities pending upgrade
 - SnsMessage: Token property was never populated from the constructor argument
diff --git a/src/BuildBot.Discord.Tests/Services/BotServiceTests.cs b/src/BuildBot.Discord.Tests/Services/BotServiceTests.cs
index 426952cc..ef5ba1e7 100644
--- a/src/BuildBot.Discord.Tests/Services/BotServiceTests.cs
+++ b/src/BuildBot.Discord.Tests/Services/BotServiceTests.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Reflection;
 using System.Threading;
 using System.Threading.Tasks;
 using BuildBot.Discord.Models;
@@ -105,4 +106,18 @@ await bot.Received(1)
                 );
         }
     }
+
+    [Fact]
+    public void Constructor_ThrowsArgumentNullException_WhenBotIsNull()
+    {
+        MessageChannel<BotMessage> messageChannel = new();
+        MessageChannel<BotReleaseMessage> releaseChannel = new();
+
+        ConstructorInfo ctor = Assert.Single(typeof(BotService).GetConstructors());
+
+        TargetInvocationException ex = Assert.Throws<TargetInvocationException>(() =>
+            ctor.Invoke([null, messageChannel, releaseChannel])
+        );
+        Assert.IsType<ArgumentNullException>(ex.InnerException);
+    }
 }

From b04c00f7f0cfb434c358d79561687ab63ad34625 Mon Sep 17 00:00:00 2001
From: Mark Ridgwell <273118822+dnyw4l3n13@users.noreply.github.com>
Date: Tue, 23 Jun 2026 16:23:17 +0000
Subject: [PATCH 2/2] refactor(test): strengthen BotService null-guard
 constructor test
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- Use GetConstructor with explicit parameter types instead of Assert.Single
  on GetConstructors(), avoiding confusing failure messages if a second
  constructor is ever added
- Remove unnecessary MessageChannel allocations — the constructor throws
  before touching the channel parameters, so null suffices for those args
- Assert ParamName == "bot" on the caught ArgumentNullException so a
  mis-targeted guard is detected rather than silently passing

Prompt: Work on pull request #377 in funfair-tech/BuildBot.
---
 .../Services/BotServiceTests.cs                   | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/src/BuildBot.Discord.Tests/Services/BotServiceTests.cs b/src/BuildBot.Discord.Tests/Services/BotServiceTests.cs
index ef5ba1e7..97fb6976 100644
--- a/src/BuildBot.Discord.Tests/Services/BotServiceTests.cs
+++ b/src/BuildBot.Discord.Tests/Services/BotServiceTests.cs
@@ -110,14 +110,13 @@ await bot.Received(1)
     [Fact]
     public void Constructor_ThrowsArgumentNullException_WhenBotIsNull()
     {
-        MessageChannel<BotMessage> messageChannel = new();
-        MessageChannel<BotReleaseMessage> releaseChannel = new();
-
-        ConstructorInfo ctor = Assert.Single(typeof(BotService).GetConstructors());
-
-        TargetInvocationException ex = Assert.Throws<TargetInvocationException>(() =>
-            ctor.Invoke([null, messageChannel, releaseChannel])
+        ConstructorInfo? ctor = typeof(BotService).GetConstructor(
+            [typeof(IDiscordBot), typeof(IMessageChannel<BotMessage>), typeof(IMessageChannel<BotReleaseMessage>)]
         );
-        Assert.IsType<ArgumentNullException>(ex.InnerException);
+        Assert.NotNull(ctor);
+
+        TargetInvocationException ex = Assert.Throws<TargetInvocationException>(() => ctor.Invoke([null, null, null]));
+        ArgumentNullException ane = Assert.IsType<ArgumentNullException>(ex.InnerException);
+        Assert.Equal(expected: "bot", actual: ane.ParamName);
     }
 }