Testing

Testing Skill

Applicability

• Platforms: iOS and Android
• React Native: 0.76+ (New Architecture interop assumed unless a checklist item says otherwise)

When to Use

• Adding tests for a new feature, hook, or utility
• Reviewing whether a change is adequately tested before merge
• Deciding what to test and at which level
• Investigating a regression that tests should have caught

Guidance

What to Test

• [ ] Unit tests for hooks and utility functions
• [ ] Component tests for user-facing behaviour, not implementation details
• [ ] End-to-end flow for each critical path (e.g. with Maestro), where applicable
• [ ] Edge cases covered: empty data, error state, offline, large data sets

How to Test

• [ ] Mocks are minimal — prefer real implementations where practical
• [ ] No snapshot tests as a primary assertion (brittle, low signal)
• [ ] Tests assert observable behaviour and outputs, not internal calls
• [ ] Each test is independent and does not rely on execution order

Incorrect:

// Asserts an implementation detail — breaks on harmless refactors
expect(component.find('useFetchUsers')).toHaveBeenCalled();

Correct:

// Asserts what the user sees
render();
expect(await screen.findByText('Ada Lovelace')).toBeOnTheScreen();

Pitfalls

• Snapshot tests fail on every harmless markup change, training the team to update them without reading — they catch little and erode trust.
• Over-mocking produces tests that pass while the real integration is broken; mock only what you must (network, native modules).
• Testing implementation details (which hook ran, internal state) makes refactoring painful even when behaviour is unchanged.
• Skipping edge cases (empty, error, offline) leaves the exact states users hit in production untested.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Neha
• Source: Neha/rn-developer-skills
• License: MIT

Install and usage instructions live in the source repository linked above.