React Native Testing Patterns

This skill provides the established testing patterns for the Fitness Tracker App, ensuring high code quality and reliable automated verification.

When to Use This Skill

Use this skill when you need to:

•Write unit tests for MST models and stores
•Create component tests using React Testing Library (RTL)
•Mock Expo modules or native dependencies
•Implement E2E flows using Maestro
•Test services, utility functions, or API logic

Unit Testing (MST)

Model Testing

typescript

import { MyModel } from "@/models/MyModel"

describe("MyModel", () => {
  it("can be created", () => {
    const instance = MyModel.create({ id: "1", name: "Test" })
    expect(instance.name).toBe("Test")
  })

  it("handles actions correctly", () => {
    const instance = MyModel.create({ id: "1", name: "Test" })
    instance.setName("Updated")
    expect(instance.name).toBe("Updated")
  })
})

Component Testing (RTL)

Basic Component Render

tsx

import { render } from "@testing-library/react-native"
import { ThemeProvider } from "@/theme/context"
import { MyComponent } from "./MyComponent"

describe("MyComponent", () => {
  it("renders correctly", () => {
    const { getByText } = render(
      <ThemeProvider>
        <MyComponent text="Hello" />
      </ThemeProvider>
    )
    expect(getByText("Hello")).toBeDefined()
  })
})

Mocking Patterns

Mocking Expo Modules

Mocks are usually centralized in test/setup.ts.

typescript

jest.mock("expo-localization", () => ({
  getLocales: () => [{ languageTag: "en-US", textDirection: "ltr" }],
}))

E2E Testing (Maestro)

Basic Flow Pattern

yaml

appId: ${MAESTRO_APP_ID}
onFlowStart:
  - runFlow: ../shared/_OnFlowStart.yaml
---
- tapOn: "Home"
- assertVisible: "My Collection"

References

See MST_TESTING.md for detailed store testing patterns.

See COMPONENT_TESTING.md for RTL and theme provider patterns.

See MAESTRO_FLOWS.md for E2E testing best practices.