Comparing your usual unit tests to snapshot tests. The output on failure is the same. If I'd been lazier on the normal version and only checked a couple properties the snapshot test would be much more thorough by comparison. You can see why it becomes more beneficial as the data size grows (like a React element tree or an API response).

cookies_normal_.test.ts

import * as sinon from 'sinon'
import { setCookie, clearCookie } from './cookies'

describe('cookies', () => {
  it('setCookie (defaults)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    setCookie(ctx as any, 'test', 'val')
    expect(spy.callCount).toBe(1)
    expect(spy.firstCall.args).toEqual([
      'test',
      'val',
      {
        domain: 'test.host',
        httpOnly: true,
        maxAge: 10000,
        overwrite: true
      }
    ])
  })

  it('setCookie (config overrides)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    setCookie(ctx as any, 'test-overrides', 'val')
    expect(spy.callCount).toBe(1)
    expect(spy.firstCall.args).toEqual([
      'test-overrides',
      'val',
      {
        domain: 'overridden.host',
        httpOnly: true,
        maxAge: 10000,
        overwrite: false
      }
    ])
  })

  it('setCookie (direct overrides)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    setCookie(ctx as any, 'test', 'val', { domain: undefined, httpOnly: false })
    expect(spy.callCount).toBe(1)
    expect(spy.firstCall.args).toEqual([
      'test',
      'val',
      {
        domain: undefined,
        httpOnly: false,
        maxAge: 10000,
        overwrite: true
      }
    ])
  })

  it('setCookie (both overrides)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    setCookie(ctx as any, 'test-overrides', 'val', { domain: undefined })
    expect(spy.callCount).toBe(1)
    expect(spy.firstCall.args).toEqual([
      'test-overrides',
      'val',
      {
        domain: undefined,
        httpOnly: true,
        maxAge: 10000,
        overwrite: false
      }
    ])
  })

  it('clearCookie (defaults)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    clearCookie(ctx as any, 'test')
    expect(spy.callCount).toBe(1)
    expect(spy.firstCall.args).toEqual([
      'test',
      undefined,
      {
        domain: 'test.host',
        httpOnly: true,
        maxAge: 10000,
        overwrite: true
      }
    ])
  })

  it('clearCookie (config overrides)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    clearCookie(ctx as any, 'test-overrides')
    expect(spy.callCount).toBe(1)
    expect(spy.firstCall.args).toEqual([
      'test-overrides',
      undefined,
      {
        domain: 'overridden.host',
        httpOnly: true,
        maxAge: 10000,
        overwrite: false
      }
    ])
  })

  it('clearCookie (direct overrides)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    clearCookie(ctx as any, 'test', { domain: undefined, httpOnly: false })
    expect(spy.callCount).toBe(1)
    expect(spy.firstCall.args).toEqual([
      'test',
      undefined,
      {
        domain: undefined,
        httpOnly: false,
        maxAge: 10000,
        overwrite: true
      }
    ])
  })

  it('clearCookie (both overrides)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    clearCookie(ctx as any, 'test-overrides', { domain: undefined })
    expect(spy.callCount).toBe(1)
    expect(spy.firstCall.args).toEqual([
      'test-overrides',
      undefined,
      {
        domain: undefined,
        httpOnly: true,
        maxAge: 10000,
        overwrite: false
      }
    ])
  })
})

cookies_snapshots_.test.ts

import * as sinon from 'sinon'
import { setCookie, clearCookie } from './cookies'

describe('cookies', () => {
  it('setCookie (defaults)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    setCookie(ctx as any, 'test', 'val')
    expect(spy.callCount).toMatchSnapshot()
    expect(spy.firstCall.args).toMatchSnapshot()
  })

  it('setCookie (config overrides)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    setCookie(ctx as any, 'test-overrides', 'val')
    expect(spy.callCount).toMatchSnapshot()
    expect(spy.firstCall.args).toMatchSnapshot()
  })

  it('setCookie (direct overrides)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    setCookie(ctx as any, 'test', 'val', { domain: undefined, httpOnly: false })
    expect(spy.callCount).toMatchSnapshot()
    expect(spy.firstCall.args).toMatchSnapshot()
  })

  it('setCookie (both overrides)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    setCookie(ctx as any, 'test-overrides', 'val', { domain: undefined })
    expect(spy.callCount).toMatchSnapshot()
    expect(spy.firstCall.args).toMatchSnapshot()
  })

  it('clearCookie (defaults)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    clearCookie(ctx as any, 'test')
    expect(spy.callCount).toMatchSnapshot()
    expect(spy.firstCall.args).toMatchSnapshot()
  })

  it('clearCookie (config overrides)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    clearCookie(ctx as any, 'test-overrides')
    expect(spy.callCount).toMatchSnapshot()
    expect(spy.firstCall.args).toMatchSnapshot()
  })

  it('clearCookie (direct overrides)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    clearCookie(ctx as any, 'test', { domain: undefined, httpOnly: false })
    expect(spy.callCount).toMatchSnapshot()
    expect(spy.firstCall.args).toMatchSnapshot()
  })

  it('clearCookie (both overrides)', () => {
    const spy = sinon.spy()
    const ctx = { cookies: { set: spy } }
    clearCookie(ctx as any, 'test-overrides', { domain: undefined })
    expect(spy.callCount).toMatchSnapshot()
    expect(spy.firstCall.args).toMatchSnapshot()
  })
})