Case insensitive session keys JSON serializer

[arnoj]

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PR Title

Case insensitive session keys for the JSON serializer.

Addresses #536

[arnoj]

@dotnet-policy-service agree

[twsouthwick]

Thanks for the fix and the tests. I've left a request to retain the original behavior but allow you to override it.

[twsouthwick]

This is a potentially breaking change and I'd prefer it to be done via an additional option:

public class JsonSessionSerializerOptions
{
+  public IEqualityComparer<string> KeyComparer { get; set; } = StringComparer.Ordinal;
}

It should also check if the KnownKeys has been created to throw if the setter is called. I'd also be ok if changing the comparer creates a new dictionary with the new comparer and the contents of the previous.

[twsouthwick]

Additionally, if you can show that the session keys on .NET Framework were case insensitive, then we can change the default since we're already doing a major change for v2.0

[arnoj]

I understand. Hope this is OK.

AFAIR a lot of collections are case insensitive in .NET framework, but session for sure. This SO comment has some alleged history. I can't find much about classic ASP anymore, but this is the Framework location I believe.

[twsouthwick]

LGTM, just need a few tweaks to a test

[twsouthwick]

this test isn't really testing that the comparer is used, just that the keys are still there. Can you verify that the new comparer is use?

[arnoj]

Sure. It checks the key case insensitively though? The key (key2) upper case is verified it does not, and after the change that it does exists (it was registered lower case). That wouldn't work if it if the comparer didn't change?

How would you like me to test? Check the Dictionary itself?

if (options.KnownKeys is Dictionary<string, Type> dict)
{
    Assert.Equal(dict.Comparer, StringComparer.OrdinalIgnoreCase);
}

[twsouthwick]

oh I guess I read the change too quickly. lgtm :)

[twsouthwick]

oh I guess I read the change too quickly. lgtm :)