Convert shares controller spec to system spec (#31619)

spec/system/share_entrypoint_spec.rb

@@ -2,32 +2,45 @@
 
 require 'rails_helper'
 
-describe 'ShareEntrypoint', :js, :streaming do
+describe 'Share page', :js, :streaming do
   include ProfileStories
 
-  subject { page }
-
   let(:email)               { 'test@example.com' }
   let(:password)            { 'password' }
   let(:confirmed_at)        { Time.zone.now }
   let(:finished_onboarding) { true }
 
-  before do
-    as_a_logged_in_user
+  before { as_a_logged_in_user }
+
+  it 'allows posting a new status' do
     visit share_path
+
+    expect(page)
+      .to have_css('.modal-layout__mastodon')
+      .and have_css('div#mastodon-compose')
+      .and have_css('.compose-form__submit')
+
+    fill_in_form
+
+    expect(page)
+      .to have_css('.notification-bar-message', text: translations['compose.published.body'])
   end
 
-  it 'can be used to post a new status' do
-    expect(subject).to have_css('div#mastodon-compose')
-    expect(subject).to have_css('.compose-form__submit')
-
-    status_text = 'This is a new status!'
-
+  def fill_in_form
     within('.compose-form') do
-      fill_in "What's on your mind?", with: status_text
-      click_on 'Post'
+      fill_in translations['compose_form.placeholder'],
+              with: 'This is a new status!'
+      click_on translations['compose_form.publish']
     end
+  end
 
-    expect(subject).to have_css('.notification-bar-message', text: 'Post published.')
+  def translations
+    # TODO: Extract to system spec helper for re-use?
+    JSON.parse(
+      Rails
+        .root
+        .join('app', 'javascript', 'mastodon', 'locales', 'en.json')
+        .read
+    )
   end
 end