Arlecchino.Testing 2026.8.5

The headless host for applications built on the Arlecchino terminal UI framework. It builds the whole application — container, views, navigation, modals, commands — against a terminal in memory, and draws a frame when a test asks for one. There is nothing to wait for and nothing to race against.

Quick start

dotnet add package Arlecchino.Testing

using var app = new ArlecchinoTestHost(configure: arlecchino =>
    arlecchino.AddGeneratedViews().StartAt(ViewKind.Default));

Assert.Contains("hello", app.Frame(), StringComparison.Ordinal);

app.Press(ConsoleKey.A);

Assert.Equal(ViewKind.About, app.Navigator.CurrentRoute);

The configure delegate is the same ArlecchinoBuilder the real application configures, so a test starts at any route, registers a fake in place of a service, or takes the application's own registration wholesale. The size of the terminal is new ArlecchinoTestHost(width: 120, height: 40), and every test framework works — the host is a plain disposable class.

What a test can reach

• The frame as text. Frame() is the screen as a string; FrameLines(), FrameContains and FrameLineContaining ask about it without picking the string apart, and Styles() lists the ANSI sequences the frame carried, so a test can assert on colour without matching escape codes.
• Input. Press with shift, alt and control, Type for text, Click and Scroll for the mouse, and ReadFromTerminal to feed a raw escape sequence the way a terminal would.
• Time that does not pass on its own. Advance(TimeSpan.FromSeconds(1)) moves the clock rather than sleeping, and the next frame shows what fell due — timeouts, notification lifetimes and work on a timer are tested in microseconds.
• The application itself. Services, Navigator, State, History and Options are the live objects, so a test can undo, inspect a store or drive navigation directly.
• The terminal. Terminal is a FakeTerminal: Written is everything sent to it, Copied is what the application put on the clipboard, and its size can be changed mid-test to check a resize.
• FrameText — WithoutStyles, Lines, BoxWidth and the regexes behind them, for assertions written against the plain text of a frame.

Packages

They ship together and always carry the same version. This package belongs in the test project only.

Links

Documentation · Testing · Changelog · Source and issues

MIT.