Fix Rubocop warnings

config/app.rb

@@ -1,6 +1,7 @@
 require 'logger'
 require 'pathname'
 
+# Encapsulates app configuration
 module App
   class << self
     attr_reader :logger

lib/api.rb

@@ -21,7 +21,8 @@ helpers do
   def snapshot
     quotes = Snapshot.new(params).quote
 
-    if symbols = params.delete('symbols') || params.delete('currencies')
+    symbols = params.delete('symbols') || params.delete('currencies')
+    if symbols
       symbols = symbols.split(',')
       quotes[:rates].keep_if { |k, _| symbols.include?(k) }
     end
@@ -30,7 +31,9 @@ helpers do
   end
 
   def process_date
-    params[:date] = Date.new(params[:year].to_i, params[:month].to_i, params[:day].to_i)
+    params[:date] = Date.new(
+      params[:year].to_i, params[:month].to_i, params[:day].to_i
+    )
   end
 
   def halt_with_message(status, message)

lib/currency.rb

@@ -1,3 +1,4 @@
+# Wraps persisted currency data
 class Currency < Sequel::Model
   def self.last_date
     order(:date).last.date

lib/snapshot.rb

@@ -1,6 +1,7 @@
 require 'virtus'
 require 'currency'
 
+# Quotes exchange rates on a specific date
 class Snapshot
   include Virtus.model
 
@@ -8,13 +9,14 @@ class Snapshot
   attribute :date, Date
 
   def quote
-    self.date = if date
-      last_date = Currency.where("date <= '#{date}'").order(:date).last
-      raise ArgumentError.new('Date too old') unless last_date
-      last_date.date
-    else
-      Currency.last_date
-    end
+    self.date =
+      if date
+        last_date = Currency.where("date <= '#{date}'").order(:date).last
+        fail ArgumentError, 'Date too old' unless last_date
+        last_date.date
+      else
+        Currency.last_date
+      end
 
     attributes.merge(rates: rebase(rates))
   end
@@ -30,7 +32,7 @@ class Snapshot
   def rebase(rates)
     if base.upcase! != 'EUR'
       denominator = rates.update('EUR' => 1.0).delete(base)
-      raise ArgumentError.new('Invalid base') unless denominator
+      fail ArgumentError, 'Invalid base' unless denominator
       rates.each do |iso_code, rate|
         rates[iso_code] = round(rate / denominator)
       end

spec/api_spec.rb

@@ -41,7 +41,7 @@ describe 'the API' do
   end
 
   it 'allows cross-origin requests' do
-    get '/', {}, { 'HTTP_ORIGIN' => 'http://localhost' }
+    get '/', {}, 'HTTP_ORIGIN' => 'http://localhost'
     assert_equal 'http://localhost', headers['Access-Control-Allow-Origin']
   end
 end