Rspec for Pinning App

After a quick look, it appears that you're expecting a validation failure
on this test, but the "invalid attributes" you're counting on aren't --

e.g. instead of

  let(:invalid_attributes) {
      {
        first_name: @user.first_name,
        password: @user.password
      }
    }

(which won't empty the email that was already set) try

  let(:invalid_attributes) {
     {
        first_name: @user.first_name,
        password: @user.password,
        email: nil
     }
  }

and your save will fail.

HTH!