Consider adding `new DefaultHttpContext()` to `Mock<DefaultHttpContext>` alternatives

[antmdvs]

https://docs.microsoft.com/en-us/dotnet/core/compatibility/2.2-3.0#http-defaulthttpcontext-extensibility-removed

If your unit tests use Mock<DefaultHttpContext>, use Mock<HttpContext> instead.

After some research, it seems new DefaultHttpContext() is a valid way way to mock HttpContext in unit tests. Should this be added to the above-quoted line? Otherwise, it could be questioned whether newing a DefaultHttpContext() is a Microsoft-accepted practice or Mock<HttpContext> is the only recommended approach.

Supporting comments:

@JamesNK (dotnet/aspnetcore#6504 (comment)):

The difference is HttpContext requires you to mock out all the behavior that you need, while DefaultHttpContext lets you take the defaults and override only what you care about.

@davidfowl (dotnet/aspnetcore#6504 (comment)):

Most of the tests I see, new up the DefaultHttpContext (it was actually intentional to make it POCO like and newable).

@anurse (https://stackoverflow.com/questions/45959605/inspect-defaulthttpcontext-body-in-unit-test-situation#comment78887946_45960766)

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Document Details

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• ID: df2066cb-244d-0b1b-cf46-428b198e8601
• Version Independent ID: e52631de-28de-77c2-082f-e79b89b17f04
• Content: Breaking changes, version 2.2 to 3.0 - .NET Core
• Content Source: docs/core/compatibility/2.2-3.0.md
• Product: dotnet-core
• GitHub Login: @gewarren
• Microsoft Alias: gewarren

[analogrelay]

After some research, it seems new DefaultHttpContext() is a valid way way to mock HttpContext in unit tests.

Yep, it's a totally reasonable option. Since most of the properties are settable and easy to override it means you often don't even need a mock at all! I'm in favor of adding it as another alternative to that breaking change note.