[wasm][test] BrowserHttpHandler stream large responses with SetBrowserResponseStreamingEnabled

[pavelsavara]

In order to be able to use WebAssemblyEnableStreamingResponse option, the user should also set HttpCompletionOption.ResponseHeadersRead so that the content would not be cached in memory.

This is unit test covering the user scenario.
Fixes #60287

[ghost]

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Issue Details

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In order to be able to use WebAssemblyEnableStreamingResponse option, the user should also set HttpCompletionOption.ResponseHeadersRead so that the content would not be cached in memory.

This is unit test covering the customer scenario.
Fixes #60287

Author:	pavelsavara
Assignees:	-
Labels:	arch-wasm, area-System.Net.Http, test enhancement
Milestone:	7.0.0

[ManickaP]

/azp run runtime-libraries-coreclr outerloop

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[pavelsavara]

/azp run runtime-libraries-mono outerloop

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[pavelsavara]

/azp run runtime-libraries-mono outerloop

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[pavelsavara]

BrowserHttpHandler_Streaming passed on mono outerloop now. There are many unrelated failures otherwise.

[ManickaP]

src\libraries\Common\tests\System\Net\Http\ResponseStreamTest.cs(133,61): error CS0246: (NETCORE_ENGINEERING_TELEMETRY=Build) The type or namespace name 'HttpRequestOptionsKey<>' could not be found (are you missing a using directive or an assembly reference?)

Doesn't seem like unrelated... I assume it's because HttpRequestOptionsKey type doesn't exist in net48.

[lewing]

The test looks good, @pranavkm I wonder if this should be documented along with the option?

[pranavkm]

We have a quip about it on https://docs.microsoft.com/en-us/aspnet/core/blazor/call-web-api?view=aspnetcore-5.0&pivots=webassembly#httpclient-and-httprequestmessage-with-fetch-api-request-options-1.

The HTTP response is typically buffered to enable support for synchronous reads on the response content. To enable support for response streaming, use the SetBrowserResponseStreamingEnabled extension method on the request.

[campersau]

@pranavkm I guess it would be great to also mention the HttpCompletionOption.ResponseHeadersRead in the docs as well.