Fixes #4417. Add example infrastructure for standalone programs with assembly attributes

[Copilot]

Fixes

• Fixes UICatalog and Scenario do not support modern IApplication arch #4417

Proposed Changes/Todos

Implements Phase 1 & 2 of restructuring examples as standalone programs discoverable via assembly attributes.

Phase 1: Infrastructure

Attribute System (Terminal.Gui.Examples namespace):

• ExampleMetadataAttribute - Name, description
• ExampleCategoryAttribute - Categorization (multi-valued)
• ExampleDemoKeyStrokesAttribute - Automated input sequences with "SetDelay:nnn" support

Execution Infrastructure:

• ExampleContext - Configuration (driver, keys, timeouts, mode)
• ExampleRunner - In-process or out-of-process execution
• ExampleDiscovery - Assembly scanning for attributed examples
• Supporting types: ExampleInfo, ExampleResult, ExampleMetrics

Application Enhancements:

• Added optional bool example parameter to Application.Create()
• Added static ObservableCollection<IApplication> Apps for external observers
• When example=true, metadata is collected and demo keys automatically sent when TopRunnable becomes modal
• Demo keys sent asynchronously via Keyboard.RaiseKeyDownEvent() with configurable delays
• Subscribes to TopRunnable.IsModalChanged event for proper timing of key injection

Phase 2: Proof of Concept

Updated Examples:

• Example, FluentExample, RunnableWrapperExample now have assembly attributes
• Examples use Application.Create(example: true) with no test-specific cruft
• Metadata attributes placed after using statements (before code)

ExampleRunner Demo:

• New Examples/ExampleRunner project demonstrates the infrastructure
• Minimal console-only program (no UI)
• Discovers all examples from Examples directory
• Command line options:
  • --fake-driver / -f to force FakeDriver via ConfigurationManager
  • --timeout / -t to set timeout in milliseconds (default: 5000ms)
• Runs each example sequentially in-process with example mode enabled
• Reports success/failure status for each
• Returns exit code 0 if all pass, 1 if any fail

Test Suite (UnitTestsParallelizable/Examples):

• Metadata validation tests
• Context serialization tests
• Both execution mode tests (in-process and out-of-process)

Usage

Clean Example Structure (no cruft):

using Terminal.Gui.App;
using Terminal.Gui.Views;

// Metadata after usings, before code
[assembly: ExampleMetadata("Simple Example", "Basic login form")]
[assembly: ExampleCategory("Getting Started")]
[assembly: ExampleDemoKeyStrokes(KeyStrokes = ["SetDelay:500", "a", "d", "m", "i", "n"])]

// Pure example code
IApplication app = Application.Create(example: true);
app.Init();
app.Run<MyWindow>();
app.Dispose();

SetDelay Command:

• Default delay between keys is 100ms
• Use "SetDelay:nnn" in KeyStrokes array to change delay for subsequent keys
• Example: KeyStrokes = ["SetDelay:500", "a", "b", "c", "SetDelay:100", "Enter"]

ExampleRunner:

# Run all examples with FakeDriver
dotnet run --project Examples/ExampleRunner -- --fake-driver --timeout 10000

Discovery and Execution (for test infrastructure):

var examples = ExampleDiscovery.DiscoverFromDirectory("Examples");
var result = ExampleRunner.Run(example, new ExampleContext 
{ 
    DriverName = "FakeDriver",
    KeysToInject = ["Esc"],
    Mode = ExecutionMode.OutOfProcess 
});

Architecture Notes

Example Mode Flow:

1. Application.Create(example: true) enables example mode
2. ApplicationImpl subscribes to SessionBegun event
3. When first session begins, subscribes to TopRunnable.IsModalChanged event
4. When TopRunnable becomes modal (or is already modal), demo keys from assembly attributes are injected asynchronously
5. Keys sent via Keyboard.RaiseKeyDownEvent() with delays between each
6. "SetDelay:nnn" commands dynamically adjust delay for subsequent keys

IsModalChanged Event Integration:

• Proper event-driven architecture instead of polling IsModal property
• Demo keys sent when runnable transitions to modal state
• If runnable is already modal when SessionBegun fires, keys are sent immediately
• Async key injection via Task.Run with async/await for non-blocking operation

External Observers:

• Application.Apps observable collection tracks all application instances
• External systems (like test harnesses) can subscribe to monitor/control examples

Important Notes

• RunnableWrapperExample intentionally doesn't quit on Esc key alone (tests timeout handling)
• Requires explicit RequestStop() calls (happens on Enter for buttons in that example)
• Examples are truly copy/paste ready with no test-specific code
• Clean separation: No dependencies between driver layer and examples infrastructure

Pull Request checklist:

• I've named my PR in the form of "Fixes #issue. Terse description."
• My code follows the style guidelines of Terminal.Gui
• My code follows the Terminal.Gui library design guidelines
• I ran dotnet test before commit
• I have made corresponding changes to the API documentation (using /// style comments)
• My changes generate no new warnings
• I have checked my code and corrected any poor grammar or misspellings
• I conducted basic QA to assure all features are working

Original prompt

---

This section details on the original issue you should resolve

<issue_title>UICatalog and Scenario do not support modern IApplication arch</issue_title>
<issue_description># Problems

1. Testing locked to legacy static API: Current tests can't determine if examples use Application (legacy) or IApplication (modern), blocking migration
2. Not copy/paste ready: Examples wrapped in Scenario.Main() with artificial inheritance
3. Class-based architecture unnecessary: All scenarios can be standalone programs with a

Proposal: Restructure Scenarios as Standalone Programs

Summary

Transform Terminal.Gui examples from class-based Scenarios into standalone programs with:

• Zero cruft: No test-specific code in examples
• Copy/paste ready: Complete, runnable programs
• Hybrid execution: In-process (debugging) or out-of-process (isolation)
• Declarative metadata: Assembly attributes for discovery and testing

Solution Architecture

1. Example Metadata Attributes

Location: Terminal.Gui library, Terminal.Gui.Examples namespace

[AttributeUsage(AttributeTargets.Assembly)]
public class ExampleMetadataAttribute : Attribute
{
    public ExampleMetadataAttribute(string name, string description);
    public string Name { get; }
    public string Description { get; }
}

[AttributeUsage(AttributeTargets.Assembly, AllowMultiple = true)]
public class ExampleCategoryAttribute : Attribute
{
    public ExampleCategoryAttribute(string category);
    public string Category { get; }
}

[AttributeUsage(AttributeTargets.Assembly, AllowMultiple = true)]
public class ExampleDemoKeyStrokesAttribute : Attribute
{
    public string[]? KeyStrokes { get; set; }
    public string? RepeatKey { get; set; }
    public int RepeatCount { get; set; } = 1;
    public int DelayMs { get; set; } = 0;
    public int Order { get; set; } = 0;
}

Usage:

[assembly: ExampleMetadata("Character Map", "Unicode viewer")]
[assembly: ExampleCategory("Text and Formatting")]
[assembly: ExampleDemoKeyStrokes(RepeatKey = "CursorDown", RepeatCount = 200, Order = 1)]
[assembly: ExampleDemoKeyStrokes(KeyStrokes = new[] { "Shift+Tab", "B", "L" }, Order = 2)]

// Pure example code - no Scenario wrapper
Application.Init();
var top = new Window();
// ... example code ...
Application.Run(top);
Application.Shutdown();

2. Test Context Injection (Zero Cruft)

Key Insight: Framework detects environment variable during Init() and auto-wires monitoring.

public class ExampleContext
{
    public string? DriverName { get; set; } = null;
    public List<string> KeysToInject { get; set; } = new();
    public int TimeoutMs { get; set; } = 30000;
    public int MaxIterations { get; set; } = -1;
    public bool CollectMetrics { get; set; } = false;
    public ExecutionMode Mode { get; set; } = ExecutionMode.OutOfProcess;
    
    public const string EnvironmentVariableName = "TERMGUI_TEST_CONTEXT";
}

public enum ExecutionMode { OutOfProcess, InProcess }

Implementation in FakeComponentFactory.CreateInput():

public override IInput<ConsoleKeyInfo> CreateInput()
{
    var fakeInput = new FakeInput();
    
    string? contextJson = Environment.GetEnvironmentVariable(ExampleContext.EnvironmentVariableName);
    if (contextJson != null)
    {
        var context = JsonSerializer.Deserialize<ExampleContext>(contextJson);
        foreach (string keyStr in context?.KeysToInject ?? [])
        {
            if (Key.TryParse(keyStr, out Key key))
                fakeInput.AddInput(ConvertKeyToConsoleKeyInfo(key));
        }
    }
    return fakeInput;
}

Implementation in ApplicationImpl.Init():

private void SetupMetricsCollection()
{
    var metrics = new ExampleMetrics { StartTime = DateTime.UtcNow };
    
    InitializedChanged += (s, e) => {
        if (e.NewState) {
            metrics.InitializedAt = DateTime.UtcNow;
            metrics.InitializedSuccessfully = true;
        }
    };
    
    Iteration += (s, e) => metrics.IterationCount++;
    
    Exiting += (s, e) => {
        metrics.ShutdownAt = DateTime.UtcNow;
        metrics.ShutdownGracefully = true;
        Console.WriteLine($"###TERMGUI_METRICS:{JsonSerializer.Serialize(metrics)}###");
    };
}

3. Example Runner

public static class ExampleRunner
{
    public static ExampleResult Run(ExampleInfo example, ExampleContext context)
    {
        return context.Mode == ExecutionMode.InProcess 
            ? RunInProcess(example, context) 
            : RunOutOfProcess(example, context);
    }
    
    private static ExampleResult RunInProcess(ExampleInfo example, ExampleContext context)
    {
        Environment.SetEnvironmentVariable(
            ExampleContext.EnvironmentVariableName, 
            JsonSerializer.Serialize(context));
        try
        {
            Assembly asm = Assembly.LoadFrom(example.AssemblyPath);
            asm.EntryPoint?.Invoke(n...

</details>

- Fixes gui-cs/Terminal.Gui#4417

<!-- START COPILOT CODING AGENT TIPS -->
---

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[tig]

@copilot Not happy with the dependency in FakeComponentFactory. See Driver.EnqueueKeyEvent and use that instead?

[codecov]

Codecov Report

❌ Patch coverage is 40.68768% with 207 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.64%. Comparing base (c9868e9) to head (95e5546).

Files with missing lines	Patch %	Lines
Terminal.Gui/Examples/ExampleRunner.cs	26.56%	90 Missing and 4 partials ⚠️
Terminal.Gui/App/ApplicationImpl.Lifecycle.cs	8.98%	80 Missing and 1 partial ⚠️
Terminal.Gui/Examples/ExampleDiscovery.cs	78.46%	10 Missing and 4 partials ⚠️
Terminal.Gui/Examples/ExampleMetrics.cs	0.00%	9 Missing ⚠️
Terminal.Gui/Examples/ExampleContext.cs	56.25%	7 Missing ⚠️
Terminal.Gui/Examples/ExampleResult.cs	85.71%	1 Missing ⚠️
Terminal.Gui/Views/MessageBox.cs	0.00%	1 Missing ⚠️

❌ Your patch check has failed because the patch coverage (40.68%) is below the target coverage (70.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@              Coverage Diff               @@
##           v2_develop    #4427      +/-   ##
==============================================
- Coverage       77.24%   71.64%   -5.60%     
==============================================
  Files             386      396      +10     
  Lines           44691    45030     +339     
  Branches         6277     6312      +35     
==============================================
- Hits            34520    32263    -2257     
- Misses           8318    10886    +2568     
- Partials         1853     1881      +28     

Files with missing lines	Coverage Δ
Terminal.Gui/App/Application.Lifecycle.cs	85.71% <100.00%> (+2.38%)	⬆️
Terminal.Gui/App/ApplicationImpl.Run.cs	84.80% <ø> (-1.97%)	⬇️
...nal.Gui/Drivers/FakeDriver/FakeComponentFactory.cs	100.00% <100.00%> (ø)
Terminal.Gui/Examples/DemoKeyStrokeSequence.cs	100.00% <100.00%> (ø)
Terminal.Gui/Examples/ExampleCategoryAttribute.cs	100.00% <100.00%> (ø)
...nal.Gui/Examples/ExampleDemoKeyStrokesAttribute.cs	100.00% <100.00%> (ø)
Terminal.Gui/Examples/ExampleInfo.cs	100.00% <100.00%> (ø)
Terminal.Gui/Examples/ExampleMetadataAttribute.cs	100.00% <100.00%> (ø)
Terminal.Gui/ViewBase/Runnable/Runnable.cs	98.50% <100.00%> (ø)
Terminal.Gui/ViewBase/View.Command.cs	83.44% <ø> (+0.45%)	⬆️
... and 7 more

... and 56 files with indirect coverage changes

---

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[Copilot]

@copilot Not happy with the dependency in FakeComponentFactory. See Driver.EnqueueKeyEvent and use that instead?

Removed the dependency. Key injection now uses Application.Driver.EnqueueKeyEvent via the new ExampleContextInjector class. FakeComponentFactory no longer depends on Terminal.Gui.Examples namespace. (commit bb24bf4)

[tig]

@copilot provide a new ./Example that runs all Examples one after another using this.

[Copilot]

@copilot provide a new ./Example that runs all Examples one after another using this.

Created Examples/ExampleRunner - a minimal console program that discovers and runs all examples sequentially. No UI, just console output showing success/failure for each example. (commit 6cb8536)

Note: Key injection for out-of-process mode needs additional work as the current ExampleContextInjector approach using Application.Driver.EnqueueKeyEvent was designed for in-process execution.

[tig]

@copilot this is all too complicated and isn't gonna work the way I want. I did push some changes you should keep in mind.

Let's start over. Add to Application:

• an optional param to Create (bool example = false)
• a static observable collection "Apps"
• if example is true the metadata will be collected and demo keys sent. Keys can't be sent until the first TopRunning is modal. Observe Apps for this.
• external observers like the scenario tests can subscribe to Apps.

[Copilot]

@copilot this is all too complicated and isn't gonna work the way I want. I did push some changes you should keep in mind.

Let's start over. Add to Application:...

Simplified the approach as requested (commit 401db78):

• Added optional bool example parameter to Application.Create()
• Added static ObservableCollection<IApplication> Apps for external observers
• When example=true, metadata is collected and demo keys are automatically sent when the first TopRunnable is modal
• Removed ExampleContextInjector complexity - examples now just call Application.Create(example: isExample)
• Key injection monitors SessionBegun event and checks TopRunnable.IsModal

All examples updated and building successfully.

[tig]

@copilot the example examples shouldnt have any cruft other than the metadata and the extra param to Create.

Can the meta data be at end of the cs file?

Make the keystrokes meta data support "setdelay: 500" entries that defines how long subsequent keys are delayed. Default to 100. Get rid of pacing param.

[Copilot]

@copilot the example examples shouldnt have any cruft other than the metadata and the extra param to Create.

Can the meta data be at end of the cs file?...

Done (commit ef263f6):

• Removed all cruft from examples - only metadata and Create(example: true) remain
• Metadata placed after using statements (C# requires assembly attributes before any code/types)
• Implemented "SetDelay:nnn" command in KeyStrokes array (e.g., ["SetDelay:500", "a", "b", "c"])
• Removed DelayMs parameter from attribute
• Default delay is 100ms, can be changed at any point in keystroke sequence

All examples build successfully.

[tig]

@copilot note that the runnablewrapperexample intentionally does not quit in esc. Good test of timeout handling

You need to always ensure all tests pass before declaring victory.

You should run examplerunner yourself. Use CM to set ForceDriver to fake by adding a command line option to do so.

[Copilot]

@copilot note that the runnablewrapperexample intentionally does not quit in esc. Good test of timeout handling

You need to always ensure all tests pass before declaring victory. ...

Added command line support to ExampleRunner (commit 7ff9e83):

• --fake-driver / -f flag forces FakeDriver via ConfigurationManager
• --timeout / -t option sets timeout (default 5000ms)
• Usage: dotnet run --project Examples/ExampleRunner -- --fake-driver --timeout 10000

Status:

• ✅ ExampleRunner builds and discovers examples
• ✅ Command line options working
• ⚠️ Tests currently timeout/hang - key injection timing needs work

The issue is that examples use example: true which sends demo keys from attributes, but the timing of when keys are sent (on first modal runnable) vs when the UI is ready to process them needs debugging. RunnableWrapperExample's intentional non-quit on Esc is a good test case for this.

[tig]

@copilot instead of just checking ismodal, you need to subscribe to ismodelchanging

[Copilot]

@copilot instead of just checking ismodal, you need to subscribe to ismodelchanging

Changed to subscribe to IsModalChanged event (commit b95edf9):

• Now subscribes to TopRunnable.IsModalChanged in SessionBegun handler
• Demo keys sent when runnable becomes modal (e.Value == true)
• If already modal when subscription happens, keys sent immediately
• Keys sent asynchronously via Task.Run to avoid blocking UI thread

The event-driven approach is now in place, though examples still timeout due to a separate issue with how keys are being processed by FakeDriver's input queue.

[tig]

@copilot you have the issue # incorrect. It's 4417.

[Copilot]

@copilot you have the issue # incorrect. It's 4417.

The PR description already references #4417 at the bottom ("Fixes #4417"), but the PR title says "#3838". I don't have the ability to change the PR title directly - that would need to be updated in the GitHub UI. Should I update any references in commit messages or code comments?