Disable macOS GitHub Actions jobs by default; opt-in Templates tests on non-PR runs

[Copilot]

• Add issue reference [CI] macOS runner scarcity is delaying rolling builds for hours and leading to cancellations #15615 as a comment in eng/Testing.targets above the RunOnGithubActionsMacOS default

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[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 -- 15616

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 15616"

[Copilot]

Pull request overview

Updates the repo’s CI test-matrix defaults so macOS GitHub Actions coverage is opt-in rather than opt-out, and selectively enables macOS for template tests on non-PR GitHub Actions runs.

Changes:

• Change RunOnGithubActionsMacOS default from enabled (outside PRs) to disabled everywhere unless explicitly set.
• Opt Aspire.Templates.Tests into macOS runs only on GitHub Actions non-PR builds.
• Update CI documentation to reflect the new macOS-default-off behavior and show an opt-in pattern.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
tests/Aspire.Templates.Tests/Aspire.Templates.Tests.csproj	Opts template tests into macOS only for GitHub Actions non-PR runs.
eng/Testing.targets	Makes macOS runs disabled-by-default via RunOnGithubActionsMacOS fallback.
docs/ci/TestingOnCI.md	Documents new default behavior and adds an example macOS opt-in condition.

[joperezr]

[radical]

/backport to release/13.2

[github-actions]

Started backporting to release/13.2 (link to workflow run)

[aspire-repo-bot]

@radical backporting to release/13.2 failed, the patch most likely resulted in conflicts. Please backport manually!

git am output

$ git am --3way --empty=keep --ignore-whitespace --keep-non-patch changes.patch

Applying: Disable macOS GitHub Actions jobs by default; opt-in Templates tests on non-PR runs
Using index info to reconstruct a base tree...
M	eng/Testing.targets
Falling back to patching base and 3-way merge...
Auto-merging eng/Testing.targets
CONFLICT (content): Merge conflict in eng/Testing.targets
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config set advice.mergeConflict false"
Patch failed at 0001 Disable macOS GitHub Actions jobs by default; opt-in Templates tests on non-PR runs
Error: The process '/usr/bin/git' failed with exit code 128

Link to workflow output