Tauri App Testing

Testing patterns specific to Tauri v2 desktop applications.

The WebKit-Only Rule

Tauri uses WebKit as its rendering engine on all platforms. When writing Playwright E2E tests for a Tauri frontend, always test against WebKit:

// playwright.config.ts
import { defineConfig, devices } from "@playwright/test";

export default defineConfig({
  projects: [
    {
      name: "webkit",
      use: { ...devices["Desktop Safari"] },
    },
  ],
});

The Core Crate Pattern

Extract platform-independent business logic into a separate Rust crate that has no Tauri dependencies. This crate can be tested with standard cargo test without needing a Tauri application context:

src-tauri/
  Cargo.toml          # depends on core + tauri
  src/
    main.rs           # Tauri setup, commands
    commands.rs       # #[tauri::command] handlers
core/
  Cargo.toml          # no Tauri dependency
  src/
    lib.rs
    settings.rs       # pure Rust logic
    file_ops.rs       # file operations
    transforms.rs     # data transforms

# core/Cargo.toml
[package]
name = "myapp-core"
version = "0.1.0"
edition = "2021"

[dependencies]
serde = { version = "1", features = ["derive"] }
serde_json = "1"
# No tauri dependency here

// core/src/settings.rs
use serde::{Deserialize, Serialize};

#[derive(Debug, Serialize, Deserialize, PartialEq)]
pub struct Settings {
    pub theme: String,
    pub font_size: u32,
}

impl Settings {
    pub fn with_theme(mut self, theme: &str) -> Self {
        self.theme = theme.to_string();
        self
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_with_theme() {
        let settings = Settings {
            theme: "light".to_string(),
            font_size: 14,
        };
        let updated = settings.with_theme("dark");
        assert_eq!(updated.theme, "dark");
        assert_eq!(updated.font_size, 14);
    }
}

Backend Bridge Mock Adapter Pattern

In a Tauri app, the frontend communicates with the Rust backend through IPC commands. For frontend testing, mock this bridge:

// src/adapters/backend.ts -- the real adapter
import { invoke } from "@tauri-apps/api/core";

export interface BackendAdapter {
  getSettings(): Promise<Settings>;
  saveSettings(settings: Settings): Promise<void>;
  readFile(path: string): Promise<string>;
}

export const tauriBackend: BackendAdapter = {
  async getSettings() {
    return invoke<Settings>("get_settings");
  },
  async saveSettings(settings) {
    return invoke("save_settings", { settings });
  },
  async readFile(path) {
    return invoke<string>("read_file", { path });
  },
};

// src/adapters/mock-backend.ts -- for testing
import type { BackendAdapter, Settings } from "./backend";

export function createMockBackend(
  overrides: Partial<BackendAdapter> = {}
): BackendAdapter {
  return {
    async getSettings() {
      return { theme: "dark", fontSize: 14 };
    },
    async saveSettings() {},
    async readFile() {
      return "mock file content";
    },
    ...overrides,
  };
}

// In the app entry point
import { tauriBackend } from "./adapters/backend";
import { createMockBackend } from "./adapters/mock-backend";

const backend =
  import.meta.env.MODE === "test"
    ? createMockBackend()
    : tauriBackend;

The 8-Step Escalation Ladder

For Tauri apps, the escalation ladder extends beyond the standard 5 levels:

Step-by-Step Guide

Steps 1-3: Fast, automatable, no browser needed

# Step 1: Rust core logic
cd core && cargo test

# Step 2: Frontend unit tests
pnpm vitest --project unit

# Step 3: Frontend component tests
pnpm vitest --project component

Steps 4-6: Need a browser, still automatable

# Step 4: E2E against dev server (WebKit only)
pnpm dev &
npx playwright test --project=webkit

# Step 5: E2E against production build
pnpm build
pnpm preview &
npx playwright test --project=webkit

# Step 6: Visual verification
verify-ui --url http://localhost:4173 --selector ".app" --check "display: flex"

Steps 7-8: Need full Tauri app

# Step 7: Tauri dev mode
pnpm tauri dev
# Manual testing in the actual Tauri window

# Step 8: Production build
pnpm tauri build
# Test the built .dmg / .msi / .AppImage

CI Configuration for Tauri Projects

# .github/workflows/test.yml
jobs:
  rust-tests:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: cd core && cargo test

  frontend-tests:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: pnpm/action-setup@v4
      - run: pnpm install
      - run: pnpm vitest run

  e2e-tests:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: pnpm/action-setup@v4
      - run: pnpm install
      - run: npx playwright install webkit --with-deps
      - run: pnpm build && pnpm preview &
      - run: npx playwright test --project=webkit