About testa
Testa is an MCP server and CLI for testing iOS apps in the Simulator, aimed at AI agents and developers. It exposes screen reading and real touch controls, and can record agent-driven runs as flows for replay in CI without a model.
Key features
- 01Read screens as compact text
- 02Tap, type, swipe, and use gestures
- 03Control simulator device features
- 04Record and replay flow files
- 05Replay flows in CI with JUnit output
Use cases
- 01Have an agent check an app's welcome screen
- 02Test interfaces without adding testIDs
- 03Record a flow and replay it in CI
MCP support
Testa exposes iOS Simulator screen observation and interaction to MCP clients. `testa setup` registers the server for Claude Code, and other clients can configure `testa mcp`.
Configuration
Local server config is the same for every client. Copy it into your client’s MCP config file.
npx -y @valewnrt/testa-mcpTESTA_MCP_FULLSet to 1 to expose all 40 tools instead of the 13-tool token-lean default.TESTA_UDIDTarget a specific simulator UDID instead of the booted one.Local servers need a runtime on your machine (e.g. Node.js 18+). Config file locations differ by client; see your client’s docs.
Tools
Local servers expose tools only once running on your machine, and the maintainer has not provided a tool list.
Details
From the project READMETesta gives Claude Code, Codex, Cursor or any MCP client eyes and hands in the
iOS Simulator. It reads the screen as compact text, taps, types and swipes with
real touch events, and checks the result. It works with React Native, Expo and
SwiftUI apps, and you don't have to add a single testID. When the agent is
done, save the run as a flow file and replay it in CI without a model.
Install
Requires macOS with Xcode 26 (iOS 26 simulators).
brew tap valewnrt/testa
brew install testa
testa setup # installs the Claude Code skill and registers the MCP server
Or build from source: git clone https://github.com/valewnrt/testa && cd testa && ./install.sh.
Connect your agent
testa setup already configures Claude Code. For other agents:
codex mcp add testa -- testa mcp # Codex
{ "mcpServers": { "testa": { "command": "testa", "args": ["mcp"] } } }
The JSON goes into Cursor's .cursor/mcp.json or any other MCP client config.
Then ask your agent something like "Launch the app in the simulator, sign up
with a test account and check that the welcome screen appears."
More in docs/agents.md.
Try it yourself
Testa is a plain CLI, so you can drive it by hand too:
$ testa boot "iPhone 17 Pro"
$ testa install ./MyApp.app && testa launch com.example.myapp
$ testa ui
19 elements (on screen)
e2 StaticText "ready" #status @201,89
e5 Button "Tap me" #tapButton @102,171
e18 TextField #textInput =type here @201,601
…
$ testa tap "Tap me"
tapped e5 Button Tap me
-- ui changes --
~ e2 StaticText "tap:1" #status @201,89
~ e6 StaticText "count: 1" #tapCount @41,208
$ testa assert "#status" label=tap:1
PASS label tap:1
The first command starts a background daemon (a few seconds, once). After that, each command takes about 60 ms.
What makes it different
- No app changes needed. Testa reads the accessibility tree and falls back to on-device OCR (Apple Vision) for anything that isn't in it: system sheets, canvas-drawn screens, games, WebViews. More →
- Built for token budgets. A screen is one line per element, about 200 tokens instead of about 1,500 for a screenshot, and every action replies with only what changed. Benchmark →
- Record once, replay in CI.
testa flow recordturns what the agent did into a plain-text flow file.testa flow runreplays it with JUnit output and failure artifacts, and there's a GitHub Action. More → - Real gestures and device control. Tap, long-press, swipe, drag-and-drop, pinch, rotate, multi-touch and hardware buttons, plus push notifications, location, Face ID, dark mode, Dynamic Type and more.
- One local binary, no dependencies. Testa talks to Apple's simulator frameworks directly: no Node, no Python, no WebDriver server. No network, no telemetry. How it works →
Status
Testa is pre-1.0 and is used against real production apps. It relies on private Apple frameworks, so a new Xcode can break it; a weekly job runs the suite against Xcode betas so breakage shows up early. Verified on Xcode 26.4 with iOS 26.4 simulators. iOS Simulator only: no real devices, no Android (why).
Documentation
- Commands: selectors, the observe → act → verify loop, full reference
- Using Testa from an AI agent: MCP setup, tools, token cost
- Testing apps without testIDs
- Flows & CI: flow files, recording, GitHub Action
- How it works · Security model
- How Testa compares to Maestro, Appium, idb and Argent
- Troubleshooting & limitations
Contributing
Bug reports, Xcode-compatibility reports and pull requests are welcome. Start with CONTRIBUTING.md; questions and ideas go to Discussions. Changes are listed in the CHANGELOG.
Acknowledgements
Testa's HID and accessibility work was informed by studying Meta's idb (MIT); no idb code is linked or bundled. Thanks to everyone who has contributed.
License
Comments
New to MCP?
From what the protocol is to installing your first server, these answers cover most first questions.
An open protocol that defines how AI applications connect to external tools and data in a uniform way. Clients talk to the model; MCP servers provide tools, resources and prompt templates. They exchange standard messages, so one server can be reused by many clients.