Null objects task

NullObjects/NullObjects.Src/INullChecker.cs

@@ -0,0 +1,15 @@
+namespace Zachet;
+
+/// <summary>
+/// Interface for null checker used in NullCounter 
+/// </summary>
+/// <typeparam name="T">Type of which will be elements you check for null</typeparam>
+public interface INullChecker<T>
+{
+    /// <summary>
+    /// Check if element is null
+    /// </summary>
+    /// <param name="element">element to check for null</param>
+    /// <returns>True if element is null, false if not null</returns>
+    bool IsNull(T element);
+}

NullObjects/NullObjects.Src/IntNullChecker.cs

@@ -0,0 +1,17 @@
+namespace Zachet;
+
+/// <summary>
+/// Null checker for ints which considers zeroes as nulls
+/// </summary>
+public class IntNullChecker : INullChecker<int>
+{
+    /// <summary>
+    /// check if element is null
+    /// </summary>
+    /// <param name="value">element to check</param>
+    /// <returns></returns>
+    public bool IsNull(int value)
+    {
+        return value == 0;
+    }
+}

NullObjects/NullObjects.Src/NullCounter.cs

@@ -0,0 +1,27 @@
+namespace Zachet;
+
+/// <summary>
+/// Class with method to count null objects in IEnumerable 
+/// </summary>
+public static class NullCounter
+{
+    /// <summary>
+    /// Count null objects int collection
+    /// </summary>
+    /// <typeparam name="T">Any type for which you have null checker</typeparam>
+    /// <param name="list">Collection implementing IEnumerable (to iterate through it)</param>
+    /// <param name="nullChecker">Object which can check if element of T type is null</param>
+    /// <returns>Count of null objects</returns>
+    public static int CountNullObjects<T>(IEnumerable<T> list, INullChecker<T> nullChecker)
+    {
+        int count = 0;
+        foreach (var item in list)
+        {
+            if (nullChecker.IsNull(item))
+            {
+                ++count;
+            }
+        }
+        return count;
+    }
+}

NullObjects/NullObjects.Src/NullObjects.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

NullObjects/NullObjects.Tests/NullObjects.Tests.csproj

@@ -0,0 +1,28 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+
+    <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="coverlet.collector" Version="6.0.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
+    <PackageReference Include="NUnit" Version="3.14.0" />
+    <PackageReference Include="NUnit.Analyzers" Version="3.9.0" />
+    <PackageReference Include="NUnit3TestAdapter" Version="4.5.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Using Include="NUnit.Framework" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\NullObjects.Src\NullObjects.csproj" />
+  </ItemGroup>
+
+</Project>

NullObjects/NullObjects.Tests/Tests.cs

@@ -0,0 +1,28 @@
+namespace NullObjects.Tests;
+using Zachet;
+
+public class Tests
+{
+    readonly List<int> emptyList = [];
+    readonly List<int> noNullObjectsList = [1, 2, 3, 4, 5, 6, 7, 8];
+    readonly List<int> listWithNulls = [1, 5, 0, 2, 4, 0, 0, 5, 2];
+    readonly IntNullChecker intNullChecker = new();
+
+    [Test]
+    public void EmptyListTest()
+    {
+        Assert.That(NullCounter.CountNullObjects<int>(emptyList, intNullChecker), Is.EqualTo(0));
+    }
+
+    [Test]
+    public void NoNullObjectsTest()
+    {
+        Assert.That(NullCounter.CountNullObjects<int>(noNullObjectsList, intNullChecker), Is.EqualTo(0));
+    }
+
+    [Test]
+    public void ListWithNullsTest()
+    {
+        Assert.That(NullCounter.CountNullObjects<int>(listWithNulls, intNullChecker), Is.EqualTo(3));
+    }
+}

NullObjects/NullObjects.sln

@@ -0,0 +1,28 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.0.31903.59
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "NullObjects", "NullObjects.Src\NullObjects.csproj", "{536D1FA1-4750-4984-9BB1-4339F97B77B0}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "NullObjects.Tests", "NullObjects.Tests\NullObjects.Tests.csproj", "{A627F83F-5227-4E1B-9251-247EE85157ED}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{536D1FA1-4750-4984-9BB1-4339F97B77B0}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{536D1FA1-4750-4984-9BB1-4339F97B77B0}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{536D1FA1-4750-4984-9BB1-4339F97B77B0}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{536D1FA1-4750-4984-9BB1-4339F97B77B0}.Release|Any CPU.Build.0 = Release|Any CPU
+		{A627F83F-5227-4E1B-9251-247EE85157ED}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{A627F83F-5227-4E1B-9251-247EE85157ED}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{A627F83F-5227-4E1B-9251-247EE85157ED}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{A627F83F-5227-4E1B-9251-247EE85157ED}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+EndGlobal