Restore terminal cursor visibility on exit in collect-linux

[Copilot]

Fix terminal cursor visibility in dotnet-trace collect-linux

Problem

The dotnet-trace collect-linux command hides the terminal cursor during operation but fails to restore it on exit, leaving users with an invisible cursor that requires manual restoration via tput cnorm or reset.

Solution

Added cursor visibility restoration in the finally block with proper state tracking to ensure the cursor is restored correctly on all exit paths.

Changes Made

1. CollectLinuxCommand.cs: Enhanced cursor visibility handling

   • Cache original cursor visibility state before hiding
   • Only hide cursor when !Console.IsOutputRedirected
   • Restore original cursor state in finally block only if changed
   • Prevents changing cursor on early return paths (e.g., --probe)

2. CollectLinuxCommandFunctionalTests.cs: Updated and improved tests

   • Renamed test to CollectLinuxCommand_DoesNotChangeCursorVisibility_WhenOutputIsRedirected to better reflect behavior
   • Converted to theory with InlineData to test both true and false initial cursor states
   • Verifies cursor remains in original state when output is redirected
   • Removed brittle line number reference from comment

Testing

• All 32 CollectLinuxCommand tests passing (31 passed, 1 skipped for platform)
  • Theory now runs twice: once with cursor initially visible, once with cursor initially hidden
• All cursor visibility tests passing
• No regressions in existing functionality

Code Changes

bool cursorVisibilityChanged = false;
bool originalCursorVisible = false;

// Only hide cursor if output is not redirected
if (!Console.IsOutputRedirected)
{
    originalCursorVisible = Console.CursorVisible;
    Console.CursorVisible = false;
    cursorVisibilityChanged = true;
}

// In finally block:
if (cursorVisibilityChanged)
{
    Console.CursorVisible = originalCursorVisible;
}

Original prompt

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This section details on the original issue you should resolve

<issue_title>dotnet-trace collect-linux leaves terminal cursor hidden after tracing completes</issue_title>
<issue_description>### Description

After dotnet-trace collect-linux finishes collecting a trace and exits, the terminal cursor remains hidden. The cursor is not restored to its visible state on exit, leaving the user with an invisible cursor in their terminal session.

Steps to Reproduce

1. Open a terminal session.
2. Run dotnet-trace collect-linux -p <pid> (or any valid collect-linux invocation).
3. Wait for trace collection to complete, or stop it with Ctrl+C / Enter.
4. Observe that the terminal cursor is no longer visible after the tool exits.
5. The terminal is still functional (typing works), but the cursor is invisible.

Expected Behavior

After dotnet-trace collect-linux exits — whether through normal completion, user-initiated stop, or signal — the terminal cursor should be restored to its visible state. The tool should ensure terminal state cleanup happens on all exit paths.

Actual Behavior

The cursor remains hidden after the tool exits. Users must manually restore it by running tput cnorm or reset to get their cursor back.

Additional Context

• The tool likely hides the cursor (e.g., via ANSI escape \e[?25l) during collection for TUI/progress rendering but does not emit the corresponding show-cursor sequence (\e[?25h) on exit.
• The fix should ensure cursor restoration on all exit paths: normal exit, SIGINT, SIGTERM, and any error/panic paths.
• Consider using a cleanup guard or defer/finally pattern to guarantee terminal state is restored regardless of how the tool exits.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes dotnet-trace collect-linux leaves terminal cursor hidden after tracing completes #5706

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[hoyosjs]

I tested and this seems to be working correctly.

[Copilot]

Pull request overview

Fixes terminal state cleanup for dotnet-trace collect-linux by ensuring the cursor is restored after trace collection, and adds functional tests around cursor visibility behavior.

Changes:

• Restore cursor visibility in CollectLinuxCommandHandler.CollectLinux via a finally block.
• Add functional tests for cursor visibility on success, error, and redirected-output scenarios.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
src/Tools/dotnet-trace/CommandLine/Commands/CollectLinuxCommand.cs	Adds cursor restoration logic in finally for collect-linux execution paths.
src/tests/dotnet-trace/CollectLinuxCommandFunctionalTests.cs	Adds tests intended to validate cursor visibility restoration behavior.

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[mdh1418]

@copilot the test name suggests that the cursor would be hidden and remain hidden when the output is redirected. Could it be renamed to CollectLinuxCommand_DoesNotChangeCursorVisibility_WhenOutputIsRedirected.

Can this be a theory taking in true/false as the original cursor's visibility

[mdh1418]

It would be nice to have a test validating that the cursor is still visible during tracing, but given that it's currently a synchronous method, it doesn't seem reasonably easily testable.

[Copilot]

Done in commit ecb67f1. Renamed the test to CollectLinuxCommand_DoesNotChangeCursorVisibility_WhenOutputIsRedirected and converted it to a theory with InlineData(true) and InlineData(false) to test both initial cursor visibility states.