Pinned statuses (#4675)

* Pinned statuses

* yarn manage:translations

spec/models/status_pin_spec.rb

@@ -0,0 +1,41 @@
+require 'rails_helper'
+
+RSpec.describe StatusPin, type: :model do
+  describe 'validations' do
+    it 'allows pins of own statuses' do
+      account = Fabricate(:account)
+      status  = Fabricate(:status, account: account)
+
+      expect(StatusPin.new(account: account, status: status).save).to be true
+    end
+
+    it 'does not allow pins of statuses by someone else' do
+      account = Fabricate(:account)
+      status  = Fabricate(:status)
+
+      expect(StatusPin.new(account: account, status: status).save).to be false
+    end
+
+    it 'does not allow pins of reblogs' do
+      account = Fabricate(:account)
+      status  = Fabricate(:status, account: account)
+      reblog  = Fabricate(:status, reblog: status)
+
+      expect(StatusPin.new(account: account, status: reblog).save).to be false
+    end
+
+    it 'does not allow pins of private statuses' do
+      account = Fabricate(:account)
+      status  = Fabricate(:status, account: account, visibility: :private)
+
+      expect(StatusPin.new(account: account, status: status).save).to be false
+    end
+
+    it 'does not allow pins of direct statuses' do
+      account = Fabricate(:account)
+      status  = Fabricate(:status, account: account, visibility: :direct)
+
+      expect(StatusPin.new(account: account, status: status).save).to be false
+    end
+  end
+end