```ruby
describe FillInReplyTokensTransition do
  it "creates a reply token for all users missing a reply token" do
    users = [create(:user), create(:user)]
    users.each { |user| user.update_attribute(:reply_token, nil) }

    FillInReplyTokensTransition.new.perform

    users.each { |user| expect(user.reload.reply_token).to_not be_nil }
  end

  it "does not mess with existing reply tokens" do
    user = create(:user)
    existing_reply_token = user.reply_token

    FillInReplyTokensTransition.new.perform

    expect(user.reload.reply_token).to eq existing_reply_token
  end
end
```

Make intent of FillInReplyTokensTransition clearer
user
```ruby
describe FillInReplyTokensTransition do
  it "creates a reply token for all users missing a reply token" do
    users = [create(:user), create(:user)]
    users.each { |user| user.update_attribute(:reply_token, nil) }

    FillInReplyTokensTransition.new.perform

    users_without_tokens = User.where(reply_token: nil)
    expect(users_without_tokens).to be_empty
  end

  it "does not mess with existing reply tokens" do
    user = create(:user)
    existing_reply_token = user.reply_token

    FillInReplyTokensTransition.new.perform

    expect(user.reload.reply_token).to eq existing_reply_token
  end
end
```
assistant