Add service that generates Base(58) secure tokens

app/services/waste_carriers_engine/secure_token_service.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require "securerandom"
+
+module WasteCarriersEngine
+
+  # SecureTokenService generates a random base58 string of length 24.
+  #
+  # SecureRandom::base58 is used to generate the 24-character unique tokens, so
+  # collisions are highly unlikely.
+  #
+  # The result will contain only alphanumeric characters except 0, O, I and l
+  #
+  #   p SecureRandom.base58 #=> "4kUgL2pdQMSCQtjE"
+  #   p SecureRandom.base58(24) #=> "77TMHrHJFvFDwodq8w7Ev2m7"
+  #
+  # Copied almost verbatim from
+  # https://github.com/robertomiranda/has_secure_token
+  class SecureTokenService < BaseService
+    BASE58_ALPHABET = ("0".."9").to_a + ("A".."Z").to_a + ("a".."z").to_a - %w[0 O I l]
+
+    def run
+      SecureRandom.random_bytes(24).unpack("C*").map do |byte|
+        idx = byte % 64
+        idx = SecureRandom.random_number(58) if idx >= 58
+        BASE58_ALPHABET[idx]
+      end.join
+    end
+
+  end
+end

spec/services/waste_carriers_engine/secure_token_service_spec.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+module WasteCarriersEngine
+  RSpec.describe SecureTokenService do
+
+    describe ".run" do
+      context "the return value" do
+        it "is a string" do
+          expect(described_class.run).to be_a(String)
+        end
+
+        it "is 24 characters in length" do
+          expect(described_class.run.length).to eq(24)
+        end
+
+        it "contains only alphanumeric characters except 0, O, I and l" do
+          expect(described_class.run).to match(/^[a-km-zA-HJ-NP-Z1-9]*$/)
+        end
+      end
+
+      it "generates a different result each time it is called" do
+        results = []
+        10.times do
+          latest = described_class.run
+
+          expect(results).not_to include(latest)
+
+          results.push(latest)
+        end
+      end
+    end
+
+  end
+end