fix for multi user scenario

[xieofxie]

They are not thread-safe when multiple users call these functions.

Also we must use services.AddSingleton<IBot, TestBot>() for the state of RandomSelector._rand

[coveralls]

Pull Request Test Coverage Report for Build 96400

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 481 unchanged lines in 31 files lost coverage.
• Overall coverage increased (+0.2%) to 78.31%

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Files with Coverage Reduction	New Missed Lines	%
/libraries/Microsoft.Bot.Builder.Dialogs.Adaptive/Actions/EmitEvent.cs	1	65.22%
/libraries/Microsoft.Bot.Builder.Dialogs.Adaptive/Actions/ForEach.cs	1	96.15%
/libraries/Microsoft.Bot.Builder.Dialogs.Adaptive/Testing/TestActions/AssertReplyActivity.cs	1	80.77%
/libraries/Microsoft.Bot.Builder.Dialogs/Prompts/OAuthPrompt.cs	1	56.4%
/libraries/Microsoft.Bot.Builder/Inspection/InspectionMiddleware.cs	1	78.89%
/libraries/Microsoft.Bot.Expressions/LRUCache.cs	1	82.93%
/libraries/Microsoft.Bot.Expressions/TriggerTrees/Trigger.cs	1	84.4%
/libraries/Microsoft.Bot.Builder.Azure/CosmosDbStorageOptions.cs	2	75.0%
/libraries/Microsoft.Bot.Builder.Dialogs.Adaptive/Actions/Case.cs	2	87.5%
/libraries/Microsoft.Bot.Builder.Dialogs.Adaptive/Actions/EditArray.cs	2	78.33%

Totals
Change from base Build 94889:	0.2%
Covered Lines:	28417
Relevant Lines:	36288

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💛 - Coveralls

[boydc2014]

Looks good to me, Random.Next is not thread-safe. Request Tom and ChrisMc to review and confirm.

@xieofxie do you have a scenario that multi-thread is used, maybe we can check in with some tests if it's a typical use case?

[xieofxie]

@boydc2014 Unfortunately, after some searching, I didn't find examples about how to write tests for concurrency.

I write one myself here xieofxie@79c86cc, but it looks not good enough for me.

Typically this happens when bot is used by multiple users and they happen to run into same functions.

[chrimc62]

[tomlm]