[URI] Allows sum types to create URIs based on distinct IDs. (#78)

* Adds support for sum types

* Adds example to README

Author: mitnal

README.md

@@ -93,6 +93,15 @@ InvoiceTypeURI.build('com.example:billing:invoice:pro_forma') # => Sry::Types::C
 InvoiceTypeURI.new(id: '1042') # => #<InvoiceTypeURI 'com.example:billing:invoice:1024'>
 InvoiceTypeURI.new(id: 'pro_forma') # => Dry::Types::ConstraintError
 
+# and this can be used in sum types to coerce *distinct* IDs to the correct URI
+ltype = Dry.Types::Coercible::Integer.constrained(lt: 1000)
+LegacyInvoiceTypeURI = Studitemps::Utils::URI.build(from: InvoiceURI, context: 'legacy_invoice', id: ltype)
+
+InvoiceSumType = InvoiceTypeURI::Types::URI | LegacyInvoiceTypeURI::Types::URI
+
+InvoiceSumType[id: 23] # => #<LegacyInvoiceTypeURI 'com.example:legacy_invoice:invoice:23'>
+InvoiceSumType[id: 1023] # => #<InvoiceTypeURI 'com.example:billing:invoice:1023'>
+InvoiceSumType[id: 'x'] # => Dry::Types::CoercionError
 ```
 
 ### Extensions

lib/studitemps/utils/uri/extensions/types.rb

@@ -26,11 +26,21 @@ module Extensions
         #     URI = ::MyURI::Types::URI
         #   end
         module Types
+          module RescueConstraintError
+            def build(*_args, **_kwargs, &_block)
+              super
+            rescue Dry::Types::ConstraintError => e
+              raise Studitemps::Utils::URI::Base::InvalidURI, e
+            end
+          end
+
           ::Studitemps::Utils::URI::Builder.extensions << -> (klass) {
             types = Module.new
             types.const_set 'URI', Dry.Types.Constructor(klass) { |value| klass.build(value) }
             types.const_set 'String', Dry.Types.Constructor(String) { |value| klass.build(value).to_s }
             klass.const_set 'Types', types
+
+            klass.extend(RescueConstraintError)
           }
 
         end

spec/studitemps/uri_spec.rb

@@ -499,7 +499,23 @@ module Utils # rubocop:disable Metrics/ModuleLength
 
                 expect {
                   invoice_klass.build('com.example:billing:invoice:23')
-                }.to raise_error Dry::Types::ConstraintError
+                }.to raise_error Studitemps::Utils::URI::Base::InvalidURI
+              end
+
+              it 'supports sum types' do
+                legacy_invoice_number_type = Dry.Types::Coercible::Integer.constrained(lt: 1000)
+                legacy_invoice_klass = URI.build(
+                  from: klass, resource: 'legacy_invoice', id: legacy_invoice_number_type
+                )
+
+                sum_type = legacy_invoice_klass::Types::URI | invoice_klass::Types::URI
+
+                expect(sum_type[id: 23]).to eq legacy_invoice_klass.new(id: 23)
+                expect(sum_type[id: 1023]).to eq invoice_klass.new(id: 1023)
+
+                expect {
+                  sum_type[id: '<invalid>']
+                }.to raise_error Dry::Types::CoercionError
               end
             end
           end