feat: add validation method

Author: dvinciguerra

lib/brazil_cep.rb

@@ -3,6 +3,7 @@
 require_relative "brazil_cep/version"
 require_relative "brazil_cep/address"
 require_relative "brazil_cep/adapters"
+require_relative "brazil_cep/validation"
 
 module Brazil
   # Brazil::Cep providers a simple way to fetch address information from a Brazilian CEP
@@ -27,6 +28,8 @@ def initialize(response)
     # zipcode not found error class
     class ZipcodeNotFound < RequestError; end
 
+    include Validation
+
     # fetch address information from a Brazilian CEP
     # @param [String] cep the CEP to fetch
     # @return [Hash] the address information

lib/brazil_cep/validation.rb

@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+
+module Brazil
+  module Cep
+    # CEP ranges by state
+    RANGES = {
+      "AC" => (69900000..69999999),
+      "AL" => (57000000..57999999),
+      "AP" => (68900000..68999999),
+      "AM" => (69000000..69299999),
+      "BA" => (40000000..48999999),
+      "CE" => (60000000..63999999),
+      "DF" => (70000000..73699999),
+      "ES" => (29000000..29999999),
+      "GO" => (72800000..76799999),
+      "MA" => (65000000..65999999),
+      "MT" => (78000000..78899999),
+      "MS" => (79000000..79999999),
+      "MG" => (30000000..39999999),
+      "PA" => (66000000..68899999),
+      "PB" => (58000000..58999999),
+      "PR" => (80000000..87999999),
+      "PE" => (50000000..56999999),
+      "PI" => (64000000..64999999),
+      "RJ" => (20000000..28999999),
+      "RN" => (59000000..59999999),
+      "RS" => (90000000..99999999),
+      "RO" => (76800000..76999999),
+      "RR" => (69300000..69399999),
+      "SC" => (88000000..89999999),
+      "SP" => (01000000..19999999),
+      "SE" => (49000000..49999999),
+      "TO" => (77000000..77999999)
+    }.freeze
+
+    # Validation module
+    module Validation
+      def self.included(base)
+        base.extend(ClassMethods)
+      end
+
+      module ClassMethods
+        def valid?(cep)
+          cep = cep.to_s.gsub(/\D/, "")
+          return false if cep.size != 8
+
+          RANGES.values.any? do |group|
+            group.cover?(cep.to_i)
+          end
+        end
+      end
+    end
+  end
+end

spec/brazil_cep/validation_spec.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+RSpec.describe Brazil::Cep do
+  describe "#valid?" do
+    subject(:validation) { Brazil::Cep.valid?(cep) }
+
+    context "when the CEP is valid" do
+      let(:cep) { "88220-000" }
+
+      it { expect(validation).to be_truthy }
+    end
+
+    context "when the CEP is invalid" do
+      let(:cep) { "00000000" }
+
+      it { expect(validation).to be_falsey }
+    end
+  end
+end