Add custom errors for PDU decoding

lib/biju/pdu.rb

@@ -9,6 +9,8 @@ require 'biju/pdu/timestamp'
 require 'biju/pdu/phone_number'
 require 'biju/pdu/type_of_address'
 
+require 'biju/pdu/errors'
+
 module Biju
   module PDU
     def self.encode(phone_number, message, options = {})

lib/biju/pdu/data_coding_scheme.rb

@@ -23,7 +23,7 @@ module Biju
           if dcs & 0b11000000 == 0
             dcs = DATA_CODING_SCHEME.key(dcs & 0b00001100)
           else
-            raise 'Unsupported'
+            raise Biju::PDU::Errors::DataCodingSchemeNotSupported.new(dcs)
           end
         end
 

lib/biju/pdu/errors.rb

@@ -0,0 +1,37 @@
+module Biju
+  module PDU
+    module Errors
+      class PDUError < ::StandardError
+      end
+
+      class MalformedSms < PDUError
+        attr_reader :original_exception
+        attr_reader :pdu
+
+        def initialize(pdu, original_exception = nil)
+          @pdu = pdu
+          @original_exception = original_exception
+        end
+
+        def to_s
+          "This SMS can not be parsed: #{pdu} (#{original_exception.class}: #{original_exception})"
+        end
+      end
+
+      class DataCodingSchemeNotSupported < PDUError
+        attr_reader :data_coding_scheme
+
+        def initialize(dcs = nil)
+          @data_coding_scheme = dcs
+        end
+
+        def to_s
+          "This data coding scheme (0b#{data_coding_scheme.to_s(2)}) is not supported"
+        end
+      end
+
+      class EncodingNotSupported < PDUError
+      end
+    end
+  end
+end