Unify GetLaunchSettings implementations between Aspire.Hosting and Aspire.Hosting.Testing

[Copilot]

The launch settings file-reading logic was duplicated between LaunchProfileExtensions (in Aspire.Hosting) and DistributedApplicationFactory (in Aspire.Hosting.Testing). This extracts the shared logic into a new LaunchSettingsReader class in the shared sources folder.

Changes

• New src/Shared/LaunchProfiles/LaunchSettingsReader.cs — shared internal static class with:

  • GetLaunchSettingsFromDirectory(string? directoryPath, string resourceIdentifier) — builds the Properties/launchSettings.json path and reads it
  • ReadLaunchSettingsFile(string filePath, string resourceIdentifier) — deserializes JSON, throws DistributedApplicationException with a descriptive message on parse failure

• LaunchProfileExtensions.cs — replaces inline stream-open + JsonSerializer.Deserialize + JsonException catch block with LaunchSettingsReader.ReadLaunchSettingsFile(...). All existing special-case logic (file-based apps, .run.json fallback) is preserved.

• DistributedApplicationFactory.cs — replaces ~20 lines of duplicated path-building and file-reading in GetLaunchSettings(string?) with a single call to LaunchSettingsReader.GetLaunchSettingsFromDirectory(...).

• Aspire.Hosting.Testing.csproj — adds explicit <Compile> include for the new shared file. Aspire.Hosting and Aspire.Hosting.Azure.Functions pick it up automatically via their existing $(SharedDir)LaunchProfiles\*.cs wildcard.

Error message strings are preserved exactly, maintaining backward compatibility with existing tests.

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
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
  • No
• Does the change require an update in our Aspire docs?
  • Yes
  • No

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• dnceng.pkgs.visualstudio.com
  • Triggering command: /usr/share/dotnet/dotnet dotnet build src/Aspire.Hosting/Aspire.Hosting.csproj -p:TreatWarningsAsErrors=false (dns block)
  • Triggering command: /usr/share/dotnet/dotnet dotnet build src/Aspire.Hosting.Testing/Aspire.Hosting.Testing.csproj -p:TreatWarningsAsErrors=false (dns block)
  • Triggering command: /usr/share/dotnet/dotnet dotnet build src/Aspire.Hosting.Azure.Functions/Aspire.Hosting.Azure.Functions.csproj -p:TreatWarningsAsErrors=false (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

[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 -- 15828

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 15828"