Caitie/update test templates

[CaitieM20]

Description

Updating the Test Templates to properly dispose of resources used (Cancellation Token, HttpRequest, HttpResponse). We should ensure our templates use best practices. These were changes I needed to make before checking in to my own project.

Updated MSTest Template to leverage the CancellationToken from TestContext, XUnit Template already does this.

Fixes # (issue)

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • [] No
  • No
• Does the change require an update in our Aspire docs?
  • Yes
    • Link to aspire-docs issue (consider using one of the following templates):
      • New (or update) doc-idea template
      • New breaking-change template
      • New diagnostic template
  • No

[Copilot]

Pull Request Overview

This PR updates the Aspire test project templates to follow proper resource disposal best practices by adding using declarations for disposable resources and improving cancellation token usage across multiple test framework templates.

• Updates resource disposal patterns for HttpClient, HttpResponse, and CancellationTokenSource
• Standardizes cancellation token usage to leverage framework-provided tokens in MSTest templates
• Applies consistent best practices across XUnit, NUnit, and MSTest project templates for versions 9.3 and 9.4

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/Aspire.ProjectTemplates/templates/aspire-xunit/9.4/IntegrationTest1.cs	Added using declarations for CancellationTokenSource, HttpClient, and HttpResponse
src/Aspire.ProjectTemplates/templates/aspire-xunit/9.3/IntegrationTest1.cs	Added using declarations for CancellationTokenSource, HttpClient, and HttpResponse
src/Aspire.ProjectTemplates/templates/aspire-nunit/9.4/IntegrationTest1.cs	Added using declarations for CancellationTokenSource, HttpClient, and HttpResponse
src/Aspire.ProjectTemplates/templates/aspire-nunit/9.3/IntegrationTest1.cs	Added using declarations for CancellationTokenSource, HttpClient, and HttpResponse
src/Aspire.ProjectTemplates/templates/aspire-mstest/9.4/IntegrationTest1.cs	Added TestContext property and updated to use framework cancellation token plus using declarations
src/Aspire.ProjectTemplates/templates/aspire-mstest/9.3/IntegrationTest1.cs	Added TestContext property and updated to use framework cancellation token plus using declarations

Comments suppressed due to low confidence (2)

[danmoseley]

LGTM save the errors copilot pointed out above.
@radical do we have tests that attempt to uncomment and build this template content? I assume not (eg., there are real commnts mixed with commented code). If so it's important to test all the commented code locally. I would do this by installing the templates and newing up each one, then manually uncommenting .. it's a pain.

[danmoseley]

I think it would be fine if you like to only update the 9.4 ones. The 9.3 ones will go away soon.

[CaitieM20]

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[radical]

@radical do we have tests that attempt to uncomment and build this template content? I assume not (eg., there are real commnts mixed with commented code).

We do uncomment and run the tests in the individual test templates. And they are failing with IntegrationTest1.cs(22,10): error CS1674: 'CancellationToken': type used in a using statement must implement 'System.IDisposable'.

[davidfowl]

@danmoseley can you give this another review?

[davidfowl]

@danmoseley @radical

[radical]

Fixed the merge conflicts, and add missing tests for 9.4 .

[radical]

LGTM! Thank you for your contribution @CaitieM20!