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Lookup in C#: port to .NET 10 and add a ToLookup vs GroupBy example #2310

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Merged
vladimir-pecanac-main merged 2 commits into from
Oct 20, 2026
Merged

Lookup in C#: port to .NET 10 and add a ToLookup vs GroupBy example #2310

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10c0b16
Lookup in C#: port to .NET 10, add GroupBy snapshot example and tests
vladimir-pecanac-main Oct 18, 2026
5e87bc1
Merge branch 'main' into seo/116921-csharp-lookup
vladimir-pecanac-main Oct 20, 2026
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2 changes: 1 addition & 1 deletion csharp-linq/LookupInCSharp/LookupInCSharp/LookupInCSharp.csproj
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@

<PropertyGroup>
<OutputType>Library</OutputType>
<TargetFramework>net8.0</TargetFramework>
<TargetFramework>net10.0</TargetFramework>
<ImplicitUsings>enable</ImplicitUsings>
<Nullable>enable</Nullable>
</PropertyGroup>
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15 changes: 14 additions & 1 deletion csharp-linq/LookupInCSharp/LookupInCSharp/LookupOperations.cs
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Expand Up @@ -30,4 +30,17 @@ public static bool SearchForKeyInLookup(string key)

public static int GetLookupCount()
=> _lookup.Count;
}

public static (int FromGroupBy, int FromLookup) CountValuesAfterSourceChanges(
string key, Student newStudent)
{
List<Student> students = [.. _students];

var grouped = students.GroupBy(s => s.Name, s => s.Course);
var lookup = students.ToLookup(s => s.Name, s => s.Course);

students.Add(newStudent);

return (grouped.Single(g => g.Key == key).Count(), lookup[key].Count());
}
}
20 changes: 19 additions & 1 deletion csharp-linq/LookupInCSharp/Tests/LookupOperationsTest.cs
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Expand Up @@ -75,4 +75,22 @@ public void WhenGetLookupCountIsCalled_ThenReturnsTheLookupCount()

Assert.Equal(3, count);
}
}

[Fact]
public void GivenKeyThatDoesNotExist_WhenRetrieveValuesOfAKeyFromLookupIsCalled_ThenReturnsEmpty()
{
var values = LookupOperations.RetrieveValuesOfAKeyFromLookup("Michael Sorla");

Assert.Empty(values);
}

[Fact]
public void GivenSourceChangesAfterTheCall_WhenCountValuesAfterSourceChangesIsCalled_ThenOnlyGroupBySeesTheChange()
{
var (fromGroupBy, fromLookup) = LookupOperations.CountValuesAfterSourceChanges(
"Kate Green", new Student("Kate Green", "Taxation"));

Assert.Equal(2, fromGroupBy);
Assert.Equal(1, fromLookup);
}
}
10 changes: 5 additions & 5 deletions csharp-linq/LookupInCSharp/Tests/Tests.csproj
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
<Project Sdk="Microsoft.NET.Sdk">

<PropertyGroup>
<TargetFramework>net8.0</TargetFramework>
<TargetFramework>net10.0</TargetFramework>
<ImplicitUsings>enable</ImplicitUsings>
<Nullable>enable</Nullable>

Expand All @@ -10,10 +10,10 @@
</PropertyGroup>

<ItemGroup>
<PackageReference Include="coverlet.collector" Version="6.0.0" />
<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
<PackageReference Include="xunit" Version="2.5.3" />
<PackageReference Include="xunit.runner.visualstudio" Version="2.5.3" />
<PackageReference Include="coverlet.collector" Version="10.1.0" />
<PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.11.0" />
<PackageReference Include="xunit" Version="2.9.3" />
<PackageReference Include="xunit.runner.visualstudio" Version="4.0.1" />
</ItemGroup>

<ItemGroup>
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