DO group tests by behaviours (BDT) and preconditions

RegistrationForm.spec.ts

describe('when the user submits a valid form', () => {
  beforeEach(() => { ... })
  it('should enable the submit button', () => { ... })
  it('should register the user by calling external API', () => { ... })
})

describe('when the user submits an invalid form', () => {
  beforeEach(() => { ... })
  it('should disable the submit button', () => { ... })

  describe('by using an invalid email', () => {
    beforeEach(() => { ... })
    it('should log the appropriate error', () => { ... })
    it('should not register the user', () => { ... })
  })

  describe('by not accepting terms and conditions', () => {
    beforeEach(() => { ...})
    it('should log the appropriate error', () => { ... })
    it('should not register the user', () => { ... })
  })
})