testing

Ledger Wallet Testing Skill

Jest + MSW + React Testing Library (Desktop) / React Native Testing Library (Mobile) ❌ E2E tests → Use e2e skill

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Golden Rules

1. toBeVisible() over toBeInTheDocument() — Always. toBeInTheDocument only checks DOM presence; elements can be hidden. Use toBeInTheDocument only when testing explicitly hidden elements.
2. Search before you create — Before writing any mock, fixture, or helper, rg the codebase. If it exists, import it. If your new mock is reusable (2+ files), put it in a shared location.
3. Mock external deps only — Never mock child components. Test integration.
4. One behavior per test — Name: it("should <behavior> when <condition>").
5. Query priority: getByRole > getByLabelText > getByText > getByTestId (last resort).
6. Feature flags via store, never mocked — Use overriddenFeatureFlags in initialState.settings.
7. Use existing factories — genAccount() from @ledgerhq/ledger-wallet-framework/mocks/account, getCryptoCurrencyById() from @ledgerhq/live-common/currencies. Never recreate account/currency data from scratch.

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Quick Reference

pnpm test:jest "filename"    # Run specific file
pnpm test:jest               # Run all tests
pnpm test:jest --coverage    # Coverage report

# Coin modules (libs/coin-modules)
pnpm coin:<name> test              # Unit tests
pnpm coin:<name> test "filename"   # Specific file
pnpm coin:<name> test-integ        # Integration tests (slow)

Platform	Render Import	MSW Server
Desktop	tests/testSetup	tests/server.ts
Mobile	@tests/test-renderer	__tests__/server.ts

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Test Template

import { render, screen, waitFor } from "tests/testSetup";
import { server } from "tests/server";
import { http, HttpResponse } from "msw";

jest.mock("@ledgerhq/live-common/someService");

describe("MyComponent", () => {
  beforeEach(() => jest.clearAllMocks());

  it("should render title", () => {
    render(<MyComponent title="Test" />);
    expect(screen.getByText("Test")).toBeVisible();
  });

  it("should call onClick when button pressed", async () => {
    const onClick = jest.fn();
    const { user } = render(<MyComponent onClick={onClick} />);
    await user.click(screen.getByRole("button"));
    expect(onClick).toHaveBeenCalledTimes(1);
  });

  it("should display fetched data", async () => {
    server.use(http.get("/api/data", () => HttpResponse.json({ name: "Bitcoin" })));
    render(<MyComponent />);
    await waitFor(() => expect(screen.getByText("Bitcoin")).toBeVisible());
  });
});