Device Code Flow logs too many errors while polling

[bgavrilMS]

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name: Bug report
about: Create a report to help us improve

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Which Version of MSAL are you using ?
Note that to get help, you need to run the latest preview or non-preview version
For ADAL, please log issues to https://github.com/AzureAD/azure-activedirectory-library-for-dotnet
2.2.0

Which platform has the issue?
all, I tested with .net core

What authentication flow has the issue?

• Desktop
  • Interactive
  • WIA
  • U/P
  • [ x ] Device code flow (browserless)
• Mobile
• Web App
  • Authorization code
  • OBO
• Web API
  • OBO

Other? - please describe;

Repro

1. Create a simple app and that uses Device Code Flow (for example, the sample https://github.com/Azure-Samples/active-directory-dotnetcore-devicecodeflow-v2)
2. Add logging to it
3. Run the app and examine the logs

Actual: the logs are full of error messages capturing the "authorization_pending" exception
Expected: these should be logged as info messages, as we are just polling for the user to have entered the auth;

Error (True) MSAL 1.0.0.0 MSAL.NetCore Microsoft Windows 10.0.17134 [10/08/2018 12:37:44 - 7a951dc1-e58d-4fa1-a1ca-2d7bd4e291e7] Microsoft.Identity.Client.MsalServiceException: AADSTS70016: Pending end-user authorization.
Trace ID: 3416a13d-a656-452a-b017-80373c5b3000
Correlation ID: 7a951dc1-e58d-4fa1-a1ca-2d7bd4e291e7
Timestamp: 2018-10-08 12:37:44Z
ErrorCode: authorization_pending
StatusCode: 400
Claims:

[MarkZuber]

This is due to OAuth2Client auto-throwing an exception whenever there's an error response (non 200) and logging the exception (OAuth2Client.cs line 167). We'll need to look into error responses there because there are cases (like this one) where we don't want to throw/log since the error conditions are expected.

[jmprieur]

Let's change the severity of this error, so that it only logs when the log serverity is info.

[jmprieur]

PR available: AzureAD/azure-activedirectory-library-for-dotnet#1315