Fix launch settings stderr test assertions and container digest validation

[marcpopMSFT]

Summary

Fixes CI test failures on main caused by mismatched test assertions after recent production changes.

Launch Settings stderr (18+ tests affected)

Commit 1ebcc5e changed the 'Using launch settings from' message to write to stderr instead of stdout, but only updated tests in one file. This PR updates the remaining three test files:

• GivenDotnetRunBuildsCsProj.cs — 6 tests: moved assertions from stdout to stderr
• GivenDotnetRunBuildsVbProj.cs — 3 tests: same pattern + fixed VB path from \Properties\ → \My Project\
• RunCommandTests.cs — 1 test: changed \StdErr.Should().BeEmpty()\ to positive stderr assertion

Container Digest Validation (6 tests affected)

\ContentStore.PathForDescriptor\ used the unanchored \DigestRegexp\ ({32,}\ hex chars) which accepted invalid digests like 63-char hex strings. Replaced with a strict anchored regex requiring exactly \sha256:<64 hex chars>.

Testing

Build verified locally (
et472\ and
et11.0\ targets). These fixes address failures observed in Build 1374751.

[Copilot]

Pull request overview

Updates tests and container digest validation to match recent production behavior changes, unblocking CI by aligning assertions/validation with current dotnet run output streams and stricter digest formatting.

Changes:

• Update dotnet run tests to assert the “Using launch settings from …” message on stderr (and fix VB launchSettings path).
• Tighten container digest validation to require sha256:<64 hex> format.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
test/dotnet.Tests/CommandTests/Run/RunCommandTests.cs	Adjusts launch settings assertion to expect output on stderr.
test/dotnet.Tests/CommandTests/Run/GivenDotnetRunBuildsVbProj.cs	Moves launch settings assertions to stderr and fixes VB launchSettings path.
test/dotnet.Tests/CommandTests/Run/GivenDotnetRunBuildsCsProj.cs	Moves multiple launch settings assertions to stderr.
src/Containers/Microsoft.NET.Build.Containers/ContentStore.cs	Adds strict sha256 digest regex validation for descriptor paths.

Comments suppressed due to low confidence (1)

src/Containers/Microsoft.NET.Build.Containers/ContentStore.cs:45

• The new digest validation regex is case-sensitive for the "sha256:" prefix, but other helpers in this assembly (e.g., DigestUtils.GetShaFromDigest) accept the algorithm prefix case-insensitively. Consider making the check case-insensitive (or normalizing the prefix) so valid digests like "SHA256:<64 hex>" don’t start failing unexpectedly.

    private static readonly Regex s_sha256DigestRegex = new(@"^sha256:[0-9A-Fa-f]{64}$", RegexOptions.Compiled);

    public static string PathForDescriptor(Descriptor descriptor)
    {
        string digestString = descriptor.Digest;
        if (!s_sha256DigestRegex.IsMatch(digestString))
        {
            throw new ArgumentException($"Invalid digest: {digestString}", nameof(descriptor.Digest));
        }
        string digestValue = digestString.Substring("sha256:".Length);

[Copilot]

The test now only checks that stderr contains the substring "Using launch settings from". To make the assertion resilient and ensure the message moved streams (and isn’t duplicated), assert against the full formatted message using the known launchSettingsPath, and also assert it is not present on stdout.

[Copilot]

In this test the previous assertion that the "Using launch settings from..." message is not written to stdout was removed. Since the intent is specifically to validate the stream change, keep an explicit stdout-negative assertion to catch accidental duplication (stdout + stderr).

[MichaelSimons]

FYI #53905 supersedes the stderr fix.