Add RSpec 4 compatibility (#17652)

* Remove outdated option

04078317ba

* Use the non-globally exposed RSpec syntax

https://github.com/rspec/rspec-core/pull/2803

* Use the non-globally exposed RSpec syntax, cont

https://github.com/rspec/rspec-core/pull/2803

* Comply to strict predicate matchers

See:
 - https://github.com/rspec/rspec-expectations/pull/1195
 - https://github.com/rspec/rspec-expectations/pull/1196
 - https://github.com/rspec/rspec-expectations/pull/1277

spec/integrity/coding_style_spec.rb

@@ -17,7 +17,7 @@ def grep_file(file, regex)
   lines.count > 0 ? file : nil
 end
 
-describe 'Coding style' do
+RSpec.describe 'Coding style' do
   describe 'Javascript' do
     it 'prevents this.get("foo") pattern' do
       js_files = list_js_files('app/assets/javascripts')

spec/integrity/common_mark_spec.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
-describe "CommonMark" do
+RSpec.describe "CommonMark" do
   it 'passes spec' do
 
     SiteSetting.traditional_markdown_linebreaks = true

spec/integrity/i18n_spec.rb

@@ -20,7 +20,7 @@ def is_yaml_compatible?(english, translated)
   true
 end
 
-describe "i18n integrity checks" do
+RSpec.describe "i18n integrity checks" do
   it "has an i18n key for each Site Setting" do
     SiteSetting.all_settings.each do |s|
       next if s[:setting][/^test_/]
@@ -97,7 +97,7 @@ describe "i18n integrity checks" do
   end
 end
 
-describe "fallbacks" do
+RSpec.describe "fallbacks" do
   before do
     I18n.backend = I18n::Backend::DiscourseI18n.new
     I18n.fallbacks = I18n::Backend::FallbackLocaleList.new

spec/integrity/js_constants_spec.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-describe "constants match ruby" do
+RSpec.describe "constants match ruby" do
 
   let(:ctx) { MiniRacer::Context.new }
 

spec/integrity/oj_spec.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-describe 'Oj' do
+RSpec.describe 'Oj' do
   it "is enabled" do
     classes = Set.new
     tracer = TracePoint.new(:c_call) { |tp| classes << tp.defined_class }

spec/integrity/onceoff_integrity_spec.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-describe ::Jobs::Onceoff do
+RSpec.describe ::Jobs::Onceoff do
   it "can run all once off jobs without errors" do
     # Load all once offs
     Dir[Rails.root + 'app/jobs/onceoff/*.rb'].each do |f|

spec/integrity/site_setting_spec.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-describe "site setting integrity checks" do
+RSpec.describe "site setting integrity checks" do
   let(:site_setting_file) { File.join(Rails.root, 'config', 'site_settings.yml') }
   let(:yaml) { YAML.load_file(site_setting_file) }