```ruby
require 'spec_helper'

feature 'Toggle Whitespace Changes', js: true, feature: true do
  let(:merge_request) { create(:merge_request) }
  let(:project) { merge_request.source_project }

  before do
    login_as :admin
    visit diffs_namespace_project_merge_request_path(project.namespace, project, merge_request)
  end

  it 'has a button to toggle whitespace changes' do
    expect(page).to have_content "Hide whitespace changes"
  end

  describe 'clicking "Hide whitespace changes" button' do
    it 'toggles the "Hide whitespace changes" button' do
      click_link "Hide whitespace changes"
      expect(page).to have_content "Show whitespace changes"
    end
  end
end
```

Use variables instead of let
user
```ruby
require 'spec_helper'

feature 'Toggle Whitespace Changes', js: true, feature: true do
  before do
    login_as :admin
    merge_request = create(:merge_request)
    project = merge_request.source_project
    visit diffs_namespace_project_merge_request_path(project.namespace, project, merge_request)
  end

  it 'has a button to toggle whitespace changes' do
    expect(page).to have_content "Hide whitespace changes"
  end

  describe 'clicking "Hide whitespace changes" button' do
    it 'toggles the "Hide whitespace changes" button' do
      click_link "Hide whitespace changes"
      expect(page).to have_content "Show whitespace changes"
    end
  end
end
```
assistant