Tauri Backend Testing Skill

This skill enables Claude to generate high-quality, comprehensive tests for the Desktop Ethereal project's Tauri backend Rust code.

When to Apply This Skill

Apply this skill when the user:

•Asks to write tests for Tauri command handlers or Rust backend code
•Asks to review existing backend tests for completeness
•Mentions Tauri commands, Rust testing, or backend tests
•Requests system integration testing or IPC communication tests
•Wants to improve test coverage for backend code

Do NOT apply when:

•User is asking about frontend/React tests
•User is asking about E2E tests
•User is only asking conceptual questions without code context

Quick Reference

Tech Stack

Tool	Version	Purpose
Rust	1.70+	Programming language
Tauri	2.0+	Desktop framework
cargo-nextest	0.9+	Test runner
tokio	1.0+	Async runtime

Key Commands

bash

# Run all backend tests
cargo test

# Run tests with nextest
cargo nextest run

# Run specific test
cargo test test_name

# Generate coverage report
cargo tarpaulin --out Html

Test Structure Template

rust

#[cfg(test)]
mod tests {
    use super::*;
    use tauri::test::{mock_app, mock_window};

    // Test setup
    fn setup_test_app() -> tauri::App {
        mock_app()
    }

    // Command handler tests (REQUIRED)
    mod command_handlers {
        use super::*;

        #[test]
        fn test_command_success() {
            // Arrange
            let app = setup_test_app();
            let window = mock_window(&app, "main");
            let expected_param = "test_value";

            // Act
            let result = some_tauri_command(window, expected_param);

            // Assert
            assert!(result.is_ok());
            assert_eq!(result.unwrap(), "expected_result");
        }

        #[test]
        fn test_command_error() {
            // Arrange
            let app = setup_test_app();
            let window = mock_window(&app, "main");
            let invalid_param = "";

            // Act
            let result = some_tauri_command(window, invalid_param);

            // Assert
            assert!(result.is_err());
            assert_eq!(result.unwrap_err().to_string(), "Expected error message");
        }
    }

    // System integration tests
    mod system_integration {
        use super::*;

        #[tokio::test]
        async fn test_system_monitoring() {
            // Arrange
            let app = setup_test_app();

            // Act
            let stats = get_system_stats().await;

            // Assert
            assert!(stats.is_ok());
            let stats = stats.unwrap();
            assert!(stats.cpu_usage >= 0.0);
            assert!(stats.cpu_usage <= 100.0);
        }
    }

    // IPC communication tests
    mod ipc_communication {
        use super::*;

        #[test]
        fn test_event_emission() {
            // Arrange
            let app = setup_test_app();
            let window = mock_window(&app, "main");
            let expected_data = TestData { value: 42 };

            // Act
            let result = emit_test_event(&window, &expected_data);

            // Assert
            assert!(result.is_ok());
            // Verify event was emitted (implementation dependent)
        }
    }
}

Testing Workflow (CRITICAL)

⚠️ Incremental Approach Required

NEVER generate all test files at once. For complex modules or multi-file testing:

•Analyze & Plan: List all functions, order by complexity (simple → complex)
•Process ONE at a time: Write test → Run test → Fix if needed → Next
•Verify before proceeding: Do NOT continue to next function until current passes

code

For each function:
  ┌────────────────────────────────────────┐
  │ 1. Write test                          │
  │ 2. Run: cargo test function_name       │
  │ 3. PASS? → Mark complete, next func    │
  │    FAIL? → Fix first, then continue    │
  │ 4. Check coverage                      │
  └────────────────────────────────────────┘

Complexity-Based Order

Process in this order for multi-function testing:

•🟢 Simple pure functions (no side effects)
•🟢 Command handlers with basic logic
•🟡 Functions with system calls
•🟡 Async functions
•🔴 Complex system integration functions
•🔴 IPC communication functions (last)

Core Principles

1. AAA Pattern (Arrange-Act-Assert)

Every test should clearly separate:

•Arrange: Setup test data and environment
•Act: Call the function under test
•Assert: Verify expected outcomes

2. Black-Box Testing

•Test observable behavior, not implementation details
•Focus on inputs and outputs
•Avoid testing internal state directly

3. Single Behavior Per Test

Each test verifies ONE observable behavior:

rust

// ✅ Good: One behavior
#[test]
fn test_command_success() {
    // Test successful command execution
}

// ❌ Bad: Multiple behaviors
#[test]
fn test_command_all_cases() {
    // Test success, error, and edge cases in one test
}

4. Descriptive Naming

Use test_<function>_<behavior>_<condition>:

rust

#[test]
fn test_get_gpu_stats_returns_valid_data_when_gpu_present()
#[test]
fn test_set_click_through_fails_when_invalid_window()
#[test]
fn test_listen_for_events_handles_multiple_events()

Required Test Scenarios

Always Required (All Functions)

•Success Case: Function works as expected with valid inputs
•Error Case: Function handles errors appropriately
•Edge Cases: Boundary conditions, null/empty inputs

Conditional (When Present)

Feature	Test Focus
`Result<T, E>` return	Both Ok and Err variants
System calls	Mock system dependencies
Async operations	Test with tokio runtime
Tauri commands	Test with mock window/app
Event emission	Verify events are emitted
State mutation	Verify state changes correctly

Coverage Goals (Per Function)

For each test function generated, aim for:

•✅ 100% function coverage
•✅ 100% statement coverage
•✅ >95% branch coverage
•✅ >95% line coverage

Tauri-Specific Considerations

Testing Tauri Commands

Always test Tauri commands with mock windows:

rust

#[test]
fn test_tauri_command() {
    // Create mock app and window
    let app = mock_app();
    let window = mock_window(&app, "main");

    // Test command with mock window
    let result = tauri_command(window, param);

    // Assert result
    assert!(result.is_ok());
}

Mocking System Dependencies

For functions that interact with system resources:

rust

// Use cfg(test) to provide mock implementations
#[cfg(not(test))]
fn get_system_temperature() -> Result<u32, String> {
    // Real implementation
    nvml_wrapper::get_temperature()
}

#[cfg(test)]
fn get_system_temperature() -> Result<u32, String> {
    // Mock implementation
    Ok(75)
}

Testing Async Functions

For async Tauri functions:

rust

#[tokio::test]
async fn test_async_command() {
    // Arrange
    let app = mock_app();
    let window = mock_window(&app, "main");

    // Act
    let result = async_tauri_command(window, param).await;

    // Assert
    assert!(result.is_ok());
}

Detailed Guides

For more detailed information, refer to:

•references/workflow.md - Incremental testing workflow (MUST READ for multi-function testing)
•references/mocking.md - Mock patterns and best practices for system dependencies
•references/async-testing.md - Async operations and system calls
•references/ipc-testing.md - IPC communication and event testing
•references/command-testing.md - Tauri command handler testing

Authoritative References

Primary Specification (MUST follow)

•docs/backend-testing.md - The canonical testing specification for Desktop Ethereal backend.

Reference Examples in Codebase

•src-tauri/src/main.rs - Main application with command handlers
•src-tauri/tests/ - Integration tests (to be created)
•src-tauri/Cargo.toml - Dependencies and test configuration

Project Configuration

•src-tauri/Cargo.toml - Rust configuration
•.cargo/config.toml - Cargo configuration