Make HttpWebRequest.GetRequestStream return same instance (fixes #41403)

[Lukeuke]

Summary

Fixes a compatibility issue where HttpWebRequest.GetRequestStream() returned a new stream instance on each call, unlike .NET Framework which returns the same instance.

Changes

• Added null coalescing operators on _requestStream inside InternalGetRequestStream
• Added test GetRequestStream_ReturnsSameInstanceWithoutLoopback.

Fixes: #41403

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[liveans]

First of all, thanks for the contribution! This seems mostly ok, however we need to add async path test + fix up the async path, to have the same behavior with sync path.

CI Failures look unrelated, I re-triggered it.

[Lukeuke]

First of all, thanks for the contribution! This seems mostly ok, however we need to add async path test + fix up the async path, to have the same behavior with sync path.

CI Failures look unrelated, I re-triggered it.

I've run the same test but async and it seems to be ok. Doesn't that mean the async path will have same behavior?
GetRequestStreamAsync is invoking BeginGetRequestStream and it is calling the InternalGetRequestStream so it will return same object? Correct me if I'm wrong

[liveans]

First of all, thanks for the contribution! This seems mostly ok, however we need to add async path test + fix up the async path, to have the same behavior with sync path.
CI Failures look unrelated, I re-triggered it.

I've run the same test but async and it seems to be ok. Doesn't that mean the async path will have same behavior? GetRequestStreamAsync is invoking BeginGetRequestStream and it is calling the InternalGetRequestStream so it will return same object? Correct me if I'm wrong

System.Net.Tests.HttpWebRequestTest_Async.GetRequestStream_ReturnsSameInstanceWithoutLoopback [FAIL]
        System.InvalidOperationException : Cannot re-call BeginGetRequestStream/BeginGetResponse while a previous call
  is still in progress.

This is what I get when I convert the test to async, for the context: HttpWebRequest_Sync and HttpWebRequest_Async only affects GetResponseAsync, and even we execute the Async test suite here, new test is still using Sync path.

[Lukeuke]

First of all, thanks for the contribution! This seems mostly ok, however we need to add async path test + fix up the async path, to have the same behavior with sync path.
CI Failures look unrelated, I re-triggered it.

I've run the same test but async and it seems to be ok. Doesn't that mean the async path will have same behavior? GetRequestStreamAsync is invoking BeginGetRequestStream and it is calling the InternalGetRequestStream so it will return same object? Correct me if I'm wrong

System.Net.Tests.HttpWebRequestTest_Async.GetRequestStream_ReturnsSameInstanceWithoutLoopback [FAIL]
        System.InvalidOperationException : Cannot re-call BeginGetRequestStream/BeginGetResponse while a previous call
  is still in progress.

This is what I get when I convert the test to async, for the context: HttpWebRequest_Sync and HttpWebRequest_Async only affects GetResponseAsync, and even we execute the Async test suite here, new test is still using Sync path.

I've double checked. I had stashed changes that are fixing that error. My bad.

[stephentoub]

@liveans, why is the code tracking whether begin/end were called?

[liveans]

why is the code tracking whether begin/end were called?

I'm not sure about the historical reason, but code was in that way since I've started to work on it. So, I didn't try to break the existing functionality.

My guess is that: It was due to APM functionality, and there are tests for it in the test suite as well.
But since people should be using Task-based functions instead, I think we should be safe to delete them.