MCP TUI Test

Like Playwright, but for Terminal User Interfaces

An MCP (Model Context Protocol) server that enables AI assistants to test Terminal User Interface (TUI) applications. This server provides tools to launch, interact with, and verify TUI applications programmatically.

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Features

• Dual Testing Modes: Choose between stream mode (for CLI tools) or buffer mode (for full TUIs with position awareness)

• Launch TUI Applications: Start any terminal-based application with configurable dimensions

• Send Keyboard Input: Simulate user typing, special keys, and control combinations

• Capture Screen Output: Read and analyze the current terminal display

• Position-Based Testing: Verify text at specific screen coordinates (buffer mode)

• Cursor Tracking: Monitor cursor position in real-time (buffer mode)

• Wait for Text: Asynchronously wait for specific content to appear

• Assertions: Verify that expected content is present in the output

• Session Management: Run multiple TUI applications simultaneously

Related MCP server: MCP Console Automation Server

Testing Modes

Stream Mode (Default)

• Best for: CLI tools, command-line applications, simple interactive programs

• Uses: pexpect for stream-based testing

• Features: Text matching, pattern waiting, output capture

• Example use cases: git, npm, grep, interactive shell scripts

Buffer Mode

• Best for: Full TUI applications, ncurses apps, dialog boxes, menus

• Uses: pexpect + pyte for screen buffer emulation

• Features: All stream features PLUS position-based assertions, cursor tracking, region extraction

• Example use cases: htop, vim, dialog, interactive menus

When to use which mode:

• Use stream mode for applications that output text sequentially

• Use buffer mode for applications that draw complex UIs with cursor movement

Installation

Prerequisites

• Python 3.10 or higher

• uv

Install

Once published to PyPI, no install is needed — run it straight from uvx:

uvx mcp-tui-test

For development:

uv venv
source .venv/bin/activate
uv pip install -e ".[dev]"

Go implementation

A sibling Go implementation lives in go/ — the same tool contract (same tool names, same structured result shapes, same tui://{session_id}/screen resource), as a single static binary with zero runtime dependencies:

go install github.com/GeorgePearse/mcp-tui-test/go/cmd/mcp-tui-test@latest

{
  "mcpServers": {
    "tui-test": { "command": "mcp-tui-test" }
  }
}

Built on the official Go MCP SDK, creack/pty, and vt10x for buffer-mode screen emulation. The Python package remains the home of the pytest plugin; the two share the tool schema, so clients can't tell them apart.

Structured results

Every tool returns structured content (with an output schema), not prose: a success flag plus typed fields (screen, outcome, passed, row/col, screen_excerpt on failed assertions, error when something broke). Agents and scripts branch on fields instead of parsing ✓/✗ strings.

The current screen is also exposed as an MCP resource at tui://{session_id}/screen.

For harness-side loops, result handling, and session ordering, see Composing TUI tests in a coding harness.

Session limits & cleanup

Sessions are capped and reaped automatically:

• MCP_TUI_MAX_SESSIONS (default 8) — launching past the cap returns a structured error.

• MCP_TUI_SESSION_TTL_S (default 900) — sessions older than this are closed on the next access.

• Dead processes are reaped on every registry access and reported by list_sessions.

• All sessions are force-closed (SIGKILL escalation) at interpreter exit — no zombies.

pytest plugin

The same engine drives deterministic CI tests with no LLM in the loop. Installing the package registers a tui fixture:

def test_app_header(tui):
    s = tui.launch("my-app --demo", mode="buffer", dimensions=(120, 40))
    s.wait_until_contains("Dashboard", timeout=10)
    s.assert_at("Dashboard", 0, 2)
    s.send("q")

TuiHandle offers send, send_ctrl, expect, assert_contains, assert_at, wait_until_contains, screen, line, and cursor; failures raise AssertionError with the current screen attached. Sessions are closed at test teardown, pass or fail.

Usage

Running the MCP Server

python server.py

Or if installed as a package:

mcp-tui-test

Configure in Claude Desktop

Add this to your claude_desktop_config.json:

{
  "mcpServers": {
    "tui-test": {
      "command": "uvx",
      "args": ["mcp-tui-test"]
    }
  }
}

(A local checkout also works: "command": "python", "args": ["/path/to/mcp-tui-test/server.py"].)

## Available Tools

### `launch_tui`
Launch a TUI application for testing.

**Parameters:**
- `command` (required): The command to launch the TUI application
- `session_id` (optional): Unique identifier for this session (default: "default")
- `timeout` (optional): Command timeout in seconds (default: 30)
- `dimensions` (optional): Terminal dimensions as WIDTHxHEIGHT (default: "80x24")
- `mode` (optional): Testing mode - "stream" or "buffer" (default: "stream")

**Examples:**
```python
# Stream mode for CLI tools
launch_tui(command="python example_tui_app.py", session_id="test1")

# Buffer mode for full TUI applications
launch_tui(command="htop", session_id="test2", mode="buffer", dimensions="120x40")

send_keys

Send keyboard input to a TUI application.

Parameters:

• keys (required): Keys to send. Use \n for Enter, \t for Tab, \x1b for Escape

• session_id (optional): Session identifier (default: "default")

• delay (optional): Delay in seconds after sending keys (default: 0.1)

Example:

send_keys(keys="1\n", session_id="test1")

send_ctrl

Send a Ctrl+Key combination to the TUI application.

Parameters:

• key (required): The key to combine with Ctrl (e.g., 'c', 'd', 'z')

• session_id (optional): Session identifier (default: "default")

Example:

send_ctrl(key="c", session_id="test1")

capture_screen

Capture the current screen output of a TUI application.

Parameters:

• session_id (optional): Session identifier (default: "default")

• include_ansi (optional): Whether to include ANSI escape codes in stream mode (default: False)

• use_buffer (optional): Force buffer/stream mode. Auto-detects if None (default: None)

Examples:

# Auto-detect mode based on session
capture_screen(session_id="test1")

# Force buffer mode capture
capture_screen(session_id="test1", use_buffer=True)

expect_text

Wait for specific text to appear in the TUI output.

Parameters:

• pattern (required): Text or regex pattern to wait for

• session_id (optional): Session identifier (default: "default")

• timeout (optional): Maximum time to wait in seconds (default: 10)

Example:

expect_text(pattern="Welcome", session_id="test1", timeout=5)

assert_contains

Assert that the current screen contains specific text.

Parameters:

• text (required): Text to search for in the current screen

• session_id (optional): Session identifier (default: "default")

• use_buffer (optional): Check buffer/stream mode. Auto-detects if None (default: None)

Example:

assert_contains(text="Counter value: 1", session_id="test1")

assert_at_position (Buffer Mode Only)

Assert that specific text appears at a screen position.

Parameters:

• text (required): Text to verify at the position

• row (required): Row number (0-indexed)

• col (required): Column number (0-indexed)

• session_id (optional): Session identifier (default: "default")

Example:

# Verify "Error" appears at row 5, column 10
assert_at_position(text="Error", row=5, col=10, session_id="test1")

get_cursor_position (Buffer Mode Only)

Get the current cursor position.

Parameters:

• session_id (optional): Session identifier (default: "default")

Example:

get_cursor_position(session_id="test1")
# Returns: "Cursor position (session: test1): row 10, column 25"

get_screen_region (Buffer Mode Only)

Extract a rectangular region of the screen.

Parameters:

• row_start (required): Starting row (0-indexed, inclusive)

• row_end (required): Ending row (0-indexed, exclusive)

• col_start (optional): Starting column (0-indexed, inclusive, default: 0)

• col_end (optional): Ending column (0-indexed, exclusive, default: end of line)

• session_id (optional): Session identifier (default: "default")

Example:

# Extract rows 5-10, full width
get_screen_region(row_start=5, row_end=10, session_id="test1")

# Extract rows 5-10, columns 20-60
get_screen_region(row_start=5, row_end=10, col_start=20, col_end=60, session_id="test1")

get_line (Buffer Mode Only)

Get a specific line from the screen buffer.

Parameters:

• row (required): Row number (0-indexed)

• session_id (optional): Session identifier (default: "default")

Example:

get_line(row=3, session_id="test1")
# Returns: "Line 3 (session: test1): [line content]"

close_session

Close a TUI testing session.

Parameters:

• session_id (optional): Session identifier (default: "default")

Example:

close_session(session_id="test1")

list_sessions

List all active TUI testing sessions.

Example:

list_sessions()

Example Test Scenario

Here's how you might use this MCP to test a TUI application:

1. Launch the application:

   launch_tui(command="python example_tui_app.py")

2. Wait for it to load:

   expect_text(pattern="Welcome to the Example TUI Application")

3. Interact with it:

   send_keys(keys="1\n")

4. Verify output:

   assert_contains(text="Hello, TUI Tester!")

5. Clean up:

   close_session()

Testing the Example App

This repository includes an example TUI application (example_tui_app.py) that you can use to test the MCP server.

Run it directly:

python example_tui_app.py

Or test it through the MCP:

launch_tui(command="python example_tui_app.py")
send_keys(keys="1\n")
capture_screen()

Use Cases

• Automated Testing: Verify TUI applications behave correctly

• Integration Testing: Test command-line tools and interactive CLIs

• Documentation: Generate screenshots and examples from TUI apps

• Debugging: Inspect the state of TUI applications during development

• CI/CD: Add TUI testing to your continuous integration pipeline

Technical Details

This MCP server uses:

• FastMCP: For the MCP server implementation

• pexpect: For spawning and controlling terminal applications

• pyte: For terminal emulation and screen buffer management (buffer mode)

• ScreenSession wrapper: Combines pexpect and pyte for hybrid testing

Architecture

• Stream Mode: pexpect directly captures output stream

• Buffer Mode: pexpect output → pyte terminal emulator → screen buffer

• Auto-detection: Tools automatically use appropriate mode based on session

Limitations

• Currently designed for Unix-like systems (Linux, macOS)

• Windows support may require modifications (consider using winpty or similar)

• Mouse support in TUIs is not currently available

• Buffer mode requires slightly more memory for screen emulation

• Position-based assertions only work in buffer mode

Contributing

Contributions are welcome! Please feel free to submit issues or pull requests.

License

MIT License - see LICENSE file for details

Related Projects

• Playwright - Browser automation (inspiration for this project)

• pexpect - Python module for spawning child applications

• pyte - Python terminal emulator

• MCP - Model Context Protocol specification

Author

Created for testing TUI applications with AI assistance.

Documentation development

The site uses Material for MkDocs, matching VisionChain and Bayesian Filters.

uv venv .venv-docs
uv pip install --python .venv-docs/bin/python -r docs-requirements.txt
.venv-docs/bin/mkdocs serve
.venv-docs/bin/mkdocs build --strict

For a build you can open directly from disk with local search, use MKDOCS_OFFLINE=true .venv-docs/bin/mkdocs build --strict --site-dir /tmp/mcp-tui-test-offline. Offline builds use .html page URLs; normal builds retain the published directory URLs.