```ruby
require 'rails_helper'

RSpec.describe User, type: :model do
  it "has a valid factory" do
    create(:user).should be_valid
  end
  it "is invalid without a first_name" do
    build(:user, first_name: nil).should_not be_valid
  end
  it "is invalid without a last_name" do
    build(:user, last_name: nil).should_not be_valid
  end
  it "is invalid without an email" do
    build(:user, email: nil).should_not be_valid
  end
  it "is invalid without a phone" do
    build(:user, phone: nil).should_not be_valid
  end
  it "is invalid without a spire_id" do
    build(:user, spire_id: nil).should_not be_valid
  end
  
  describe ''
  it "returns a contact's full name as a string"
end
```

Use single quotes unless double quotes are needed
user
```ruby
require 'rails_helper'

RSpec.describe User, type: :model do
  it 'has a valid factory' do
    create(:user).should be_valid
  end
  it 'is invalid without a first_name' do
    build(:user, first_name: nil).should_not be_valid
  end
  it 'is invalid without a last_name' do
    build(:user, last_name: nil).should_not be_valid
  end
  it 'is invalid without an email' do
    build(:user, email: nil).should_not be_valid
  end
  it 'is invalid without a phone' do
    build(:user, phone: nil).should_not be_valid
  end
  it 'is invalid without a spire_id' do
    build(:user, spire_id: nil).should_not be_valid
  end
end
```
assistant