React native testing skill

React Native Testing

Priority: P1 (HIGH)

Core Rule Anchors

• [MOB-TEST-01] Tripartite Naming: Follow Method_Scenario_ExpectedBehavior.
• [MOB-TEST-02] State & Component Invariant Rule: Assert on visible user outcomes and accessible UI elements; never inspect component internal state or props directly.
• [MOB-TEST-03] Entity Invariant Rule: Test calculations, validations, and domain invariants; ban trivial echo assertions.
• [MOB-TEST-04] Contract Testing Rule: Intercept network requests at HTTP boundary (MSW) or native module boundary; ban 1:1 pass-through mock echoing without contract assertions.
• [MOB-TEST-05] Bug-First Regression Lock: Every PR resolving a bug ticket or with title fix(...) must introduce a test reproducing the defect prior to the fix.

Setup & Component Testing

• Jest & RNTL: Use @testing-library/react-native for user-centric tests. Mock native modules with jest.mock().
• Component Example:

test('increments counter on button press', () => {
  const { getByText, getByRole } = render(<Counter />);
  fireEvent.press(getByRole('button', { name: /increment/i }));
  expect(getByText('Count: 1')).toBeTruthy();
});

Best Practices

• User-Centric: Use getByRole, getByText over testID. Use findBy* for async elements.
• Integration > Unit: Test features, not implementation. Avoid brittle snapshots.
• Coverage: Coverage is diagnostic and project-configured; verify risk-weighted critical paths rather than padding code for an arbitrary percentage.

Anti-Patterns

• No Testing Implementation: Test behavior, not internals. Avoid testID overuse.
• Banned Smells: Ban vague names, inspecting component state/props, echo assertions, and pass-through mocks.

References

See references/testing-library.md for RNTL setup, mocking providers, and integration flow examples.

Canonical response anchors

When this skill applies, preserve the following domain terminology or equivalent concrete examples in the answer when relevant:

• Integration

• RNTL

• Additional task-grounded exact anchors: test behavior