Add and configure rubocop and rubocop-rspec

.rubocop.yml

@@ -1,13 +1,33 @@
+require: rubocop-rspec
+
 AllCops:
   TargetRubyVersion: 3.2
+  DisplayCopNames: true
+  NewCops: enable
+
+# ----------------------- Style -----------------------
 
 Style/StringLiterals:
   Enabled: true
-  EnforcedStyle: double_quotes
+  EnforcedStyle: single_quotes
 
 Style/StringLiteralsInInterpolation:
   Enabled: true
   EnforcedStyle: double_quotes
 
+# ----------------------- Layout ----------------------
+
 Layout/LineLength:
   Max: 120
+
+# ---------------------- Metrics ----------------------
+
+Metrics/BlockLength:
+  Exclude:
+    - '**/*_spec.rb'
+    - nostr.gemspec
+
+# ----------------------- RSpec -----------------------
+
+RSpec/ExampleLength:
+  Enabled: false

nostr.gemspec

@@ -13,6 +13,7 @@ Gem::Specification.new do |spec|
   spec.homepage = "https://github.com/wilsonsilva/nostr"
   spec.license = "MIT"
   spec.required_ruby_version = ">= 3.2.0"
+  spec.metadata["rubygems_mfa_required"] = "true"
 
   spec.metadata["homepage_uri"] = spec.homepage
   spec.metadata["source_code_uri"] = "https://github.com/wilsonsilva/nostr"
@@ -33,4 +34,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "rake", "~> 13.0"
   spec.add_development_dependency "rspec", "~> 3.12"
   spec.add_development_dependency "rubocop", "~> 1.42"
+  spec.add_development_dependency "rubocop-rspec", "2.16"
 end