Expect

    Harness uses Vitest's expect function for making assertions in your tests. The API is 100% compatible with Vitest's expect functionality.

    Basic Usage

    import { describe, test, expect } from 'react-native-harness'

describe('basic assertions', () => {
  test('primitive values', () => {
    expect(2 + 2).toBe(4)
    expect('hello').toBe('hello')
    expect(true).toBeTruthy()
    expect(false).toBeFalsy()
  })

  test('objects and arrays', () => {
    expect({ name: 'John', age: 30 }).toEqual({ name: 'John', age: 30 })
    expect([1, 2, 3]).toContain(2)
    expect(['apple', 'banana']).toHaveLength(2)
  })

  test('strings and numbers', () => {
    expect('hello world').toContain('world')
    expect('hello world').toMatch(/world/)
    expect(3.14).toBeCloseTo(3.1, 1)
    expect(10).toBeGreaterThan(5)
  })

  test('exceptions', () => {
    const throwError = () => {
      throw new Error('Something went wrong')
    }
    
    expect(throwError).toThrow()
    expect(throwError).toThrow('Something went wrong')
  })
})

    Soft Assertions

    Use expect.soft to continue test execution even when assertions fail:

    test('soft assertions', () => {
  expect.soft(1 + 1).toBe(3) // This will fail but test continues
  expect.soft(2 + 2).toBe(5) // This will also fail but test continues
  expect(3 + 3).toBe(6) // This passes
  // Test will be marked as failed due to soft assertion failures
})

    Complete API Reference

    Harness provides the complete Vitest expect API including:

    • Basic matchers: toBe, toEqual, toStrictEqual
    • Truthiness: toBeTruthy, toBeFalsy, toBeNull, toBeUndefined, toBeDefined
    • Numbers: toBeGreaterThan, toBeLessThan, toBeCloseTo
    • Strings: toMatch, toContain, toHaveLength
    • Arrays/Objects: toContain, toHaveProperty, toMatchObject
    • Exceptions: toThrow, toThrowError
    • Types: toBeInstanceOf, toBeTypeOf
    • Asymmetric matchers: expect.anything(), expect.any(), expect.arrayContaining(), etc.

    For the complete documentation of all available matchers and advanced features, please refer to the Vitest expect documentation.

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