Update Verify.XunitV3 to avoid invalid artifact paths

[radical]

Fixes #16638

Description

Updates Verify.XunitV3 from 31.1.0 to 31.16.2 so Verify no longer emits failed snapshot attachments with names that contain characters rejected by actions/upload-artifact.

We are updating this dependency because the pinned Verify.XunitV3 version is the source of the invalid artifact path. Version 31.1.0 names mismatch attachments as Verify snapshot mismatch: {path}. MTP writes that attachment name under testresults/**, so the colon in Verify snapshot mismatch: becomes part of the file path. GitHub's artifact upload action then rejects the artifact because it enforces cross-platform filename restrictions.

Verify.XunitV3 31.16.2 changed this behavior to use a path-derived attachment name instead of the colon-prefixed display string, which fixes the artifact upload failure at the source instead of renaming generated files after the test run.

Failure instance

• Run: ci.yml run 25192208839
• Job: Tests / Hosting.Azure / Hosting.Azure (ubuntu-latest)
• Step: Upload logs, and test results

Error

The path for one of the files in artifact is not valid: /testresults/_runnervmeorf1_2026-04-30_23_03_43.7907827/In/runnervmeorf1/Verify snapshot mismatch: _home_runner_work_aspire_aspire_tests_Aspire.Hosting.Azure.Tests_Snapshots_AzureDeployerTests.DeployAsync_WithFoundryAndAzureContainerApps_CreatesCorrectDependencies.received.txt.bin. Contains the following character:  Colon :

Invalid characters include:  Double quote ", Colon :, Less than <, Greater than >, Vertical bar |, Asterisk *, Question mark ?, Carriage return \r, Line feed \n

Validation

Reproduced and verified locally with a minimal xUnit v3 + Verify project (single test deliberately producing a snapshot mismatch, run through MTP with TRX reporting):

• With Verify.XunitV3 31.1.0, the generated TRX contains
  <ResultFile path=".../Verify snapshot mismatch: _..._received.txt.bin" /> — the colon-prefixed path that actions/upload-artifact rejects.
• With Verify.XunitV3 31.16.2, the same test produces no mismatch: reference in the TRX, no in-process artifact with the colon-prefixed name, and no files containing : under the test results directory.

This confirms the upgrade fixes the root cause rather than working around the symptom.

[github-actions]

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 16632

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 16632"

[Copilot]

Pull request overview

This PR updates the test-only snapshot testing dependency Verify.XunitV3 to prevent invalid snapshot attachment file names (containing :) from being written into testresults/**, which can cause actions/upload-artifact to reject uploaded artifacts in GitHub Actions runs.

Changes:

• Bump Verify.XunitV3 from 31.1.0 to 31.16.2 in test package central management.
• Add agent guidance to prefer reusing/extending existing shared helpers (especially under tests/Shared/) rather than creating new private helper utilities.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
tests/Directory.Packages.props	Updates the centrally-managed test dependency version for Verify.XunitV3.
AGENTS.md	Adds an instruction encouraging reuse of existing shared helper implementations before adding new helpers.

[github-actions]

Re-running the failed jobs in the CI workflow for this pull request because 1 job was identified as retry-safe transient failures in the CI run attempt.
GitHub was asked to rerun all failed jobs for that attempt, and the rerun is being tracked in the rerun attempt.
The job links below point to the failed attempt jobs that matched the retry-safe transient failure rules.

• Tests / Hosting-5 / Hosting-5 (windows-latest) - Job-level runner or infrastructure failure matched the transient allowlist.

[github-actions]

Re-running the failed jobs in the CI workflow for this pull request because 1 job was identified as retry-safe transient failures in the CI run attempt.
GitHub was asked to rerun all failed jobs for that attempt, and the rerun is being tracked in the rerun attempt.
The job links below point to the failed attempt jobs that matched the retry-safe transient failure rules.

• Tests / Hosting-5 / Hosting-5 (windows-latest) - Job-level runner or infrastructure failure matched the transient allowlist.