SmtpClientTest.SendAsync_CanBeCanceled_SendAsyncCancel test failed in CI

[stephentoub]

Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1052129
Build error leg or test failing: System.Net.Mail.Tests.SmtpClientTest.SendAsync_CanBeCanceled_SendAsyncCancel
Pull request: #116021

Error Message

Fill the error message using step by step known issues guidance.

{
  "ErrorMessage": "",
  "ErrorPattern": "(SendAsync_CanBeCanceled_SendAsyncCancel)|(SendMailAsync_CanBeCanceled_CancellationToken)",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1052129
Error message validated: [SendAsync_CanBeCanceled_SendAsyncCancel.*OperationCanceledException]
Result validation: ❌ Known issue did not match with the provided build.
Validation performed at: 5/27/2025 8:09:22 PM UTC

[stephentoub]

The line:

Assert.IsType<OperationCanceledException>(e.Error.InnerException);

in SendAsync_CanBeCanceled_SendAsyncCancel is too strict. It should allow for OperationCanceledException and any type deriving from it (like TaskCanceledException), not only OperationCanceledException.

[AndyAyersMS]

Also seeing this in SmtpClientTest.SendMailAsync_CanBeCanceled_CancellationToken

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