Update a Dictionary Value in C#: .NET 10, TryAdd, GetValueRefOrAddDefault and AddOrUpdate samples

[vladimir-pecanac-main]

Sample for https://code-maze.com/csharp-update-the-value-stored-in-a-dictionary/

Changes, all inside collections-dictionary/UpdateDictionaryValue:

• Both projects retargeted from net7.0 to net10.0.
• Test project moved from MSTest.TestAdapter + MSTest.TestFramework 2.2.10 to the MSTest meta package. The folder only uses Assert.AreEqual, so no test body changed for the MSTest 4 rename of Assert.ThrowsException.
• ToppingsDictionary.Toppings is now get-only ({ get; } instead of { get; private set; }).
• New AddToppingIfMissing (Dictionary.TryAdd) and AddToppingsByRef (CollectionsMarshal.GetValueRefOrAddDefault), as printed in the article.
• Program.cs prints the same sequence as the article's output blocks (olive = 3 in both runs), with the "jalepeno" spelling corrected to "jalapeno", and adds the ConcurrentDictionary.AddOrUpdate demonstration (prints 4, then 8).
• Three new tests, one per new code item (5 tests total).

Package versions, re-queried on NuGet 2026-10-09 (latest listed stable):

• Microsoft.NET.Test.Sdk 18.10.1
• MSTest 4.5.1
• coverlet.collector 10.1.0

Local checks on SDK 10.0.302 / runtime 10.0.10: dotnet build -c Release 0 warnings 0 errors; dotnet test 5 passed, 0 failed; dotnet list package --vulnerable --include-transitive: no vulnerable packages in either project.