From 4a5eeb8cf0ffe323d4c2709293e289265d7e3928 Mon Sep 17 00:00:00 2001
From: Buddhism8003 <lindemeier@purelymail.com>
Date: Sun, 14 Dec 2025 16:26:21 +0100
Subject: [PATCH] added test project for AdventOfCode.Extensions

---
 .../AdventOfCode.Extensions.Tests.csproj      | 25 +++++++++++++
 .../EnumerableExtensionsTest.cs               | 37 +++++++++++++++++++
 .../EnumerableExtensions.cs                   |  2 +-
 AdventOfCode.sln                              | 17 +++++++++
 4 files changed, 80 insertions(+), 1 deletion(-)
 create mode 100644 AdventOfCode.Extensions.Tests/AdventOfCode.Extensions.Tests.csproj
 create mode 100644 AdventOfCode.Extensions.Tests/EnumerableExtensionsTest.cs

diff --git a/AdventOfCode.Extensions.Tests/AdventOfCode.Extensions.Tests.csproj b/AdventOfCode.Extensions.Tests/AdventOfCode.Extensions.Tests.csproj
new file mode 100644
index 0000000..5c7d8d0
--- /dev/null
+++ b/AdventOfCode.Extensions.Tests/AdventOfCode.Extensions.Tests.csproj
@@ -0,0 +1,25 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net9.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+        <IsPackable>false</IsPackable>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <PackageReference Include="coverlet.collector" Version="6.0.2"/>
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0"/>
+        <PackageReference Include="xunit" Version="2.9.2"/>
+        <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2"/>
+    </ItemGroup>
+
+    <ItemGroup>
+        <Using Include="Xunit"/>
+    </ItemGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\AdventOfCode.Extensions\AdventOfCode.Extensions.csproj" />
+    </ItemGroup>
+
+</Project>
diff --git a/AdventOfCode.Extensions.Tests/EnumerableExtensionsTest.cs b/AdventOfCode.Extensions.Tests/EnumerableExtensionsTest.cs
new file mode 100644
index 0000000..2505f10
--- /dev/null
+++ b/AdventOfCode.Extensions.Tests/EnumerableExtensionsTest.cs
@@ -0,0 +1,37 @@
+using AdventOfCode.Extensions;
+namespace AdventOfCode.Extensions.Tests;
+
+public class EnumerableExtensionsTest
+{
+    [Fact]
+    public void Combinations_12_2_equals_12_21()
+    {
+        int[] data = [1, 2];
+
+        var actual = data.Combinations(2).ToArray();
+
+        Assert.Contains([1, 2], actual);
+    }
+    
+    [Fact]
+    public void Combinations_123_2_equals_12_13_23()
+    {
+        int[] data = [1, 2, 3];
+
+        var actual = data.Combinations(2).ToArray();
+
+        Assert.Contains([1, 2], actual);
+        Assert.Contains([1, 3], actual);
+        Assert.Contains([2, 3], actual);
+    }
+    
+    [Fact]
+    public void Combinations_123_3_equals_123()
+    {
+        int[] data = [1, 2, 3];
+
+        var actual = data.Combinations(3).ToArray();
+
+        Assert.Contains([1, 2, 3], actual);
+    }
+}
\ No newline at end of file
diff --git a/AdventOfCode.Extensions/EnumerableExtensions.cs b/AdventOfCode.Extensions/EnumerableExtensions.cs
index a0d05f0..c7dd053 100644
--- a/AdventOfCode.Extensions/EnumerableExtensions.cs
+++ b/AdventOfCode.Extensions/EnumerableExtensions.cs
@@ -18,7 +18,7 @@ public static class EnumerableExtensions
         {
             var validIndex = false;
             var currentIndex = 0;
-            foreach (var i in Range(0, count).Reverse())
+            for(var i = count - 1; i >= 0; i--)
             {
                 currentIndex = i;
                 if (indices[i] != i + poolLength - count)
diff --git a/AdventOfCode.sln b/AdventOfCode.sln
index 5b17a0d..cbde281 100644
--- a/AdventOfCode.sln
+++ b/AdventOfCode.sln
@@ -18,6 +18,14 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AdventOfCode.HelperClasses.
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AdventOfCode.Downloader", "AdventOfCode.Downloader\AdventOfCode.Downloader.csproj", "{43B006C3-5296-452B-BD86-225574C0E2A2}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "HelperClasses", "HelperClasses", "{60EAF50E-3D09-4886-A237-984AF6F40119}"
+EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Contracts", "Contracts", "{19D1A1FA-0E80-4C2C-A542-5AB6FB3FB18D}"
+EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Extensions", "Extensions", "{F6AF8AA9-D28F-4DC0-A689-0A1451DC6B61}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AdventOfCode.Extensions.Tests", "AdventOfCode.Extensions.Tests\AdventOfCode.Extensions.Tests.csproj", "{FCED95A0-13EC-4DB0-B572-592398BB30F3}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -56,10 +64,19 @@ Global
 		{43B006C3-5296-452B-BD86-225574C0E2A2}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{43B006C3-5296-452B-BD86-225574C0E2A2}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{43B006C3-5296-452B-BD86-225574C0E2A2}.Release|Any CPU.Build.0 = Release|Any CPU
+		{FCED95A0-13EC-4DB0-B572-592398BB30F3}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{FCED95A0-13EC-4DB0-B572-592398BB30F3}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{FCED95A0-13EC-4DB0-B572-592398BB30F3}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{FCED95A0-13EC-4DB0-B572-592398BB30F3}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{4F395AE3-DABB-4546-A4D0-5A62425FE168} = {05EBAA1C-B33B-4AFE-8635-A58D7CA509A7}
 		{197D9628-C2D1-4B33-9DB8-134F87F79904} = {05EBAA1C-B33B-4AFE-8635-A58D7CA509A7}
 		{FAB5E28F-706A-4DE1-B5FD-54E31C3A8405} = {05EBAA1C-B33B-4AFE-8635-A58D7CA509A7}
+		{D47175BB-5AD6-43A8-9287-FF5E6F1816E3} = {60EAF50E-3D09-4886-A237-984AF6F40119}
+		{3D09528A-09A7-4B0B-9D45-7D3AAB26449A} = {60EAF50E-3D09-4886-A237-984AF6F40119}
+		{0249A329-D5C1-4699-88BE-A668B362432E} = {19D1A1FA-0E80-4C2C-A542-5AB6FB3FB18D}
+		{1466A0F6-7C88-47FF-B8F8-FF30368E26DC} = {F6AF8AA9-D28F-4DC0-A689-0A1451DC6B61}
+		{FCED95A0-13EC-4DB0-B572-592398BB30F3} = {F6AF8AA9-D28F-4DC0-A689-0A1451DC6B61}
 	EndGlobalSection
 EndGlobal