[fix] Fix test output eaten by MSBuild terminal logger

[Jakub Jareš (nohwnd)]

Summary

Fixes #15509

🤖 This is an automated fix.

Root Cause

When TestCaptureOutput=false is set in Directory.Build.props (to allow live test output in the console) and the MSBuild terminal logger is active (default in .NET 8+ SDK), the terminal logger buffers all output from MSBuild sub-tasks — including test output. When tests complete, the terminal logger shows "See log file: (path)" messages. Since TestCaptureOutput=false means no log files are created, those paths point to files that don't exist, leaving developers with no visible test output.

Fix

Disable the MSBuild terminal logger in test.sh and test.cmd by setting MSBUILDTERMINALLOGGER=off before invoking the build scripts. This lets test output flow directly to the console as intended.

Developers who prefer the terminal logger UI can override the default by setting MSBUILDTERMINALLOGGER=auto before invoking the test scripts.

Testing

This is a developer-tooling change affecting only the test.sh and test.cmd scripts. No production code is modified. The change is:

• test.sh: Exports MSBUILDTERMINALLOGGER=${MSBUILDTERMINALLOGGER:-off} so the default is off but can be overridden.
• test.cmd: Sets MSBUILDTERMINALLOGGER=off if not already defined.

CI runs (azure-pipelines.yml calls ./test.sh) will also have the terminal logger disabled, which is harmless — CI output is captured by the Azure DevOps agent regardless.

🔍 Triaged by Issue Repro Triage & Auto-Fix 🔍

[Copilot]

Pull request overview

This PR addresses missing/“eaten” test output when running via the repo’s test.sh/test.cmd in environments where TestCaptureOutput=false and the .NET SDK’s MSBuild terminal logger buffers sub-task output. The fix disables the terminal logger by default in the test entry scripts, while still allowing developers to override the setting.

Changes:

• Default MSBUILDTERMINALLOGGER to off in test.sh to prevent terminal-logger buffering of test output.
• Default MSBUILDTERMINALLOGGER to off in test.cmd when the variable isn’t already defined (allowing opt-in overrides).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
test.sh	Exports MSBUILDTERMINALLOGGER (default off) before invoking the shared build/test entrypoint.
test.cmd	Sets MSBUILDTERMINALLOGGER=off (only if unset) before running eng\Build.ps1 -test.

[Jakub Jareš (nohwnd)]

🧠 Reviewed by Expert Code Reviewer

Scope

This PR touches only test.cmd and test.sh — thin wrapper scripts that bootstrap scriptroot/DOTNET_ROOT and delegate to the real build engine. No production C# code is modified.

Dimensions activated (per routing table):

• Build Script & Infrastructure Hygiene — environment variable handling, exit-code propagation, pre-delegate ordering
• Source Build & Cross-Platform Compliance — bash portability, child-process propagation

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Findings

No actionable issues found.

What was checked and passed:

Check	Result
if not defined VAR set VAR=off is the correct idiomatic CMD default-value pattern	✅
export VAR=${VAR:-off} is correct POSIX/bash syntax, sets before delegating	✅
Env var is set before the delegated script is invoked (child process inherits it)	✅
exit /b %ErrorLevel% still present in test.cmd — exit-code propagation unaffected	✅
User-override preserved on both platforms (already-set value is not overwritten)	✅
CI pipelines that pre-set MSBUILDTERMINALLOGGER before calling ./test.sh are unaffected	✅

Minor observation (no change needed):

The two scripts have slightly different empty-string semantics:

• test.sh: ${MSBUILDTERMINALLOGGER:-off} treats an empty value (="") as unset → override to off
• test.cmd: if not defined treats an empty value as defined → keeps the empty string

If a developer sets MSBUILDTERMINALLOGGER= (empty) to clear the variable, the behavior differs per platform. In practice this is irrelevant — the documented override path is MSBUILDTERMINALLOGGER=auto, not empty-string. No action needed.

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PR Description Alignment

The title and description accurately describe the change. The root-cause explanation (TestCaptureOutput=false + terminal logger buffering → missing log-file paths), the fix, and the CI-impact claim all match the diff exactly. ✅

🧠 Reviewed by Expert Code Reviewer 🧠