Uno Testing UI

Uno Platform UI Testing Agent Skill

Prerequisite: This skill requires the Uno App MCP (the uno_app_* tools), provided by the Uno tooling. It is a separate server from the documentation MCP used by other skills. Before proceeding, confirm the uno_app_* tools are available; if they are not, stop and tell the user to enable the Uno tooling rather than attempting to test without them.

This skill enables automated UI testing of Uno Platform applications using the Uno App MCP server tools. It provides comprehensive guidance for launching apps, inspecting UI elements, simulating user interactions, and validating visual output.

Overview

The Uno App MCP server exposes a set of tools that allow agents to:

• Start and stop Uno Platform applications
• Capture screenshots for visual validation
• Inspect the visual tree to discover UI elements
• Interact with elements using automation peers
• Simulate keyboard and pointer input
• Retrieve element data context for state validation

Prerequisites

1. The Uno App MCP server must be configured in your environment
2. The target application must be an Uno Platform project with MCP client integration
3. The project must have valid target frameworks (e.g., net9.0-desktop, net9.0-browserwasm)

Quick Start Workflow

For most UI testing scenarios, follow this workflow:

1. Start the app → uno_app_start
2. Verify app is running → uno_app_get_runtime_info
3. Capture initial screenshot → uno_app_get_screenshot
4. Get visual tree → uno_app_visualtree_snapshot
5. Interact with elements → uno_app_element_peer_default_action or input tools
6. Validate results → Screenshots + visual tree inspection
7. Close the app → uno_app_close

Available MCP Tools

App Lifecycle Tools

Visual Inspection Tools

Interaction Tools

Diagnostic Tools

Detailed Tool Usage

Starting an Application

Use uno_app_start to launch the application:

Tool: uno_app_start
Parameters:
  - projectPath: Full path to the .csproj file (must be within MCP working directory)
  - targetFramework: Target framework moniker (e.g., "net9.0-desktop", "net9.0-browserwasm")
  - args: Optional command-line arguments (array)

Example scenarios:

• Desktop testing: targetFramework = "net9.0-desktop"
• WebAssembly testing: targetFramework = "net9.0-browserwasm"

Important: Always verify the app started successfully by calling uno_app_get_runtime_info afterward.

Inspecting the Visual Tree

Use uno_app_visualtree_snapshot to get an XML representation of the UI:

Tool: uno_app_visualtree_snapshot
Parameters:
  - justMyCode: Filter to user-defined elements only (default: true)
  - includeBounds: Include element bounds for coordinate-based interaction (default: false)
  - includeHidden: Include hidden/collapsed elements (default: false)

The returned XML contains element handles (refs) that can be used with interaction tools. Each element includes:

• Element type and name
• Automation properties
• Handle/reference for interactions
• Bounds (if requested)

Tip: Set justMyCode: true to reduce noise from framework elements and focus on application UI.

Interacting with Elements

Preferred approach: Use automation peers when element handles are available.

1. Default Action (most common):

   Tool: uno_app_element_peer_default_action
   Parameters:
     - elementRef: Handle from visual tree snapshot
   

   This invokes the natural action (click for buttons, toggle for checkboxes, etc.)

2. Specific Action (for advanced scenarios):

   Tool: uno_app_element_peer_action
   Parameters:
     - elementRef: Handle from visual tree snapshot
     - action: Specific automation action name
     - actionParameters: Optional parameters array
   

Fallback approach: Use coordinate-based input when handles aren't suitable.

3. Pointer Click:

   Tool: uno_app_pointer_click
   Parameters:
     - x: Absolute physical X coordinate
     - y: Absolute physical Y coordinate
     - button: "left", "middle", or "right"
     - clickCount: Number of clicks (default: 1)
     - delayBetweenPresseAndReleaseInMs: Delay in milliseconds (default: 10)
   

4. Keyboard Input:

   Tool: uno_app_key_press
   Parameters:
     - virtualKey: VirtualKey name (e.g., "Enter", "Tab", "A")
     - virtualKeyModifiers: Optional modifiers ("control", "shift", "menu", "windows")
     - unicodeKey: Optional explicit unicode character
   

5. Text Entry:

   Tool: uno_app_type_text
   Parameters:
     - text: String of text to type
     - intervalInMs: Delay between key presses
   

Capturing Screenshots

Use uno_app_get_screenshot for visual validation:

Tool: uno_app_get_screenshot
Parameters:
  - fileType: "png" or "jpeg"
  - quality: Image quality 1-100 (default: 75)
  - path: Optional file path to save the screenshot

Screenshots are essential for:

• Visual regression testing
• Documenting test execution
• Debugging failed tests
• Validating layout and styling

Validating Element State

Use uno_app_get_element_datacontext to inspect bound data:

Tool: uno_app_get_element_datacontext
Parameters:
  - elementRef: Handle from visual tree snapshot

Returns an XML representation of the element's DataContext, useful for verifying:

• ViewModel state
• Data binding correctness
• Business logic results

Testing Patterns

Pattern 1: Simple Click Test

1. Start the app
2. Get visual tree snapshot
3. Find the target button by name/type
4. Call uno_app_element_peer_default_action with its handle
5. Get new visual tree or screenshot
6. Verify expected changes

Pattern 2: Form Input Test

1. Start the app
2. Navigate to the form (if needed)
3. Get visual tree to find input fields
4. For each field:
   • Call uno_app_element_peer_default_action to focus
   • Call uno_app_type_text to enter data
5. Submit the form
6. Validate results via screenshot or data context

Pattern 3: Navigation Test

1. Start the app
2. Get initial visual tree snapshot
3. Trigger navigation (click nav button, etc.)
4. Wait briefly for navigation to complete
5. Get new visual tree snapshot
6. Verify the expected page/view is displayed

Pattern 4: Visual Regression Test

1. Start the app
2. Navigate to target state
3. Capture screenshot with uno_app_get_screenshot
4. Compare with baseline image
5. Report differences

Best Practices

Element Selection

• Prefer automation peers over coordinate clicks for reliability
• Use justMyCode: true to filter framework elements
• Look for elements with x:Name or AutomationProperties.AutomationId

Test Stability

• Always verify app is running with uno_app_get_runtime_info before testing
• Add brief delays between rapid interactions if needed
• Refresh visual tree after actions that change UI state

Assertions

• Use screenshots for visual validation
• Use uno_app_get_element_datacontext for data validation
• Check visual tree for element presence/absence

Cleanup

• Always call uno_app_close at the end of tests (desktop)
• Handle test failures gracefully with cleanup

Troubleshooting

"No connected app instance"

• The app hasn't started or has crashed
• Call uno_app_start to launch the app
• Check build output for errors

Element not found in visual tree

• Element may be hidden/collapsed (try includeHidden: true)
• Element may be dynamically created (refresh the tree)
• Check if using correct framework filter

Interaction not working

• Verify element handle is from latest tree snapshot
• Check if element is enabled and visible
• Try coordinate-based input as fallback

Screenshots are blank or incorrect

• Ensure app window is visible and not minimized
• Check for correct target framework
• Verify app has finished rendering

References

For detailed implementation patterns, see:

• references/INTERACTION-PATTERNS.md - Detailed interaction examples
• references/VISUAL-TREE-GUIDE.md - Visual tree inspection guide