5.2 測試策略：從單元測試到端對端測試#

        /  E2E  \        少而貴：全流程，最接近真實
       / 整合測試 \       中：多模組協作（API + DB）
      /  單元測試   \      多而廉：純函數，快如閃電

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

    #[test]
    fn slug_title_trims_whitespace() {
        assert_eq!(slug("  hello  "), "hello");
    }

    #[test]
    fn empty_title_is_invalid() {
        assert!(CreateTodo { title: "".into() }.validate().is_err());
    }
}

// tests/api.rs
#[tokio::test]
async fn create_then_toggle_todo() {
    let app = test_app().await;                        // 測試專用 DB，隨機 schema
    let token = app.login("a@b.c", "pw123456").await;

    let todo: Todo = app.post("/todos", &json!({"title": "write tests"}), &token).await;
    assert!(!todo.done);

    let toggled: Todo = app.patch(&format!("/todos/{}", todo.id), &token).await;
    assert!(toggled.done);
}

use proptest::prelude::*;

proptest! {
    // 性質：對任意標題，slug 永不含空白且不超長
    #[test]
    fn slug_never_has_spaces(s in "[a-zA-Z0-9 ]{0,200}") {
        let out = slug(&s);
        prop_assert!(!out.contains(' '));
        prop_assert!(out.len() <= 200);
    }
}

proptest! {
    fn todo_json_roundtrip(t in todo_strategy()) {
        let json = serde_json::to_string(&t).unwrap();
        let back: Todo = serde_json::from_str(&json).unwrap();
        prop_assert_eq!(t, back);      // 序列化必須是等價變換
    }
}

it('renders done marker when todo.done', () => {
  render(<TodoItem todo={{ id: '1', title: 'x', done: true }} onToggle={jest.fn()} />);
  expect(screen.getByText(/✓/)).toBeTruthy();
});

it('rejects malformed todo from server', () => {
  expect(() => TodoSchema.parse({ id: 'not-uuid' })).toThrow();
});

# .maestro/login.yaml
appId: com.example.myapp
---
- launchApp
- tapOn: "Email"
- inputText: "a@b.c"
- tapOn: "Password"
- inputText: "pw123456"
- tapOn: "登入"
- assertVisible: "我的待辦"

# .github/workflows/ci.yml（節選）
jobs:
  backend:
    runs-on: ubuntu-latest
    services:
      postgres: { image: postgres:16, env: { POSTGRES_PASSWORD: test } }
    steps:
      - uses: actions/checkout@v4
      - run: cargo fmt --check && cargo clippy -- -D warnings
      - run: cargo test
  frontend:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npx tsc --noEmit           # 型別檢查本身也是測試！
      - run: npm test