Improve Rubocop config, fix offenses

.rubocop.yml

@@ -11,7 +11,7 @@ AllCops:
   Exclude:
     - bin/*
     - gemfiles/*
-    - spec/**/*
+    - spec/dummy/**/*
 
 Gemspec/RequireMFA:
   Enabled: false
@@ -44,3 +44,10 @@ Layout/EmptyLinesAroundBlockBody:
 
 Layout/EmptyLinesAroundModuleBody:
   Enabled: false
+
+#########
+# RSPEC #
+#########
+
+RSpec/InstanceVariable:
+  Enabled: false

spec/config_rspec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Configure RSpec
 RSpec.configure do |config|
   # Use DB agnostic schema by default
@@ -15,11 +17,11 @@
     DatabaseCleaner.clean_with(:truncation)
   end
 
-  config.before(:each) do
+  config.before do
     DatabaseCleaner.start
   end
 
-  config.after(:each) do
+  config.after do
     DatabaseCleaner.clean
   end
 end

spec/lib/auto_increment/active_record_spec.rb

@@ -1,7 +1,9 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe AutoIncrement::ActiveRecord do
-  before :all do
+  before :all do # rubocop:disable RSpec/BeforeAfterAll
     @account1 = Account.create name: 'My Account'
     @account2 = Account.create name: 'Another Account', code: 50
 
@@ -29,7 +31,7 @@
   end
 
   describe 'locks query for increment' do
-    before :all do
+    before :all do # rubocop:disable RSpec/BeforeAfterAll
       threads = []
       lock = Mutex.new
       @account = Account.create name: 'Another Account', code: 50
@@ -47,7 +49,7 @@
     end
 
     let(:account_last_letter_code) do
-      @accounts.sort_by(&:letter_code).last.letter_code
+      @accounts.sort_by(&:letter_code).last.letter_code # rubocop:disable Style/RedundantSort
     end
 
     it { expect(@accounts.size).to eq 25 }

spec/lib/auto_increment/incrementor_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe AutoIncrement::Incrementor do
@@ -12,20 +14,18 @@
   }.each do |previous_value, next_value|
     describe "increment value for #{previous_value}" do
       it do
-        allow(subject).to receive(:maximum) { previous_value }
-        expect(subject.send(:increment)).to eq next_value
+        allow(subject).to receive(:maximum) { previous_value } # rubocop:disable RSpec/SubjectStub, RSpec/NamedSubject
+        expect(subject.send(:increment)).to eq next_value # rubocop:disable RSpec/NamedSubject
       end
     end
   end
 
   describe 'initial value of string' do
-    subject do
-      AutoIncrement::Incrementor.new initial: 'A'
-    end
+    subject(:incrementor) { described_class.new initial: 'A' }
 
     it do
-      allow(subject).to receive(:maximum) { nil }
-      expect(subject.send(:increment)).to eq 'A'
+      allow(incrementor).to receive(:maximum).and_return(nil) # rubocop:disable RSpec/SubjectStub
+      expect(incrementor.send(:increment)).to eq 'A'
     end
   end
 end