feat: add pb:diff relation to pact resource to view a diff with an arbitrary pact version

Closes: pact-foundation#190

Author: bethesque

lib/pact_broker/api/decorators/pact_decorator.rb

@@ -99,6 +99,15 @@ def to_hash(options = {})
           }
         end
 
+        link :'pb:diff' do | options |
+          {
+            title: "Diff with another specified version of this pact",
+            href: templated_diff_url(represented, options.fetch(:base_url)),
+            templated: true
+
+          }
+        end
+
         link :'pb:pact-webhooks' do | options |
           {
             title: "Webhooks for the pact between #{represented.consumer.name} and #{represented.provider.name}",

lib/pact_broker/api/pact_broker_urls.rb

@@ -51,7 +51,7 @@ def pact_url base_url, pact
       end
 
       def pact_version_url pact, base_url
-        "#{pactigration_base_url(base_url, path)}/pact-version/#{pact.sha}"
+        "#{pactigration_base_url(base_url, pact)}/pact-version/#{pact.pact_version_sha}"
       end
 
       def pact_url_from_params base_url, params
@@ -81,6 +81,10 @@ def previous_distinct_diff_url pact, base_url
         pact_url(base_url, pact) + "/diff/previous-distinct"
       end
 
+      def templated_diff_url pact, base_url = ''
+        pact_version_url(pact, base_url) + "/diff/pact-version/{pactVersion}"
+      end
+
       def previous_distinct_pact_version_url pact, base_url
         pact_url(base_url, pact) + "/previous-distinct"
       end

spec/lib/pact_broker/api/decorators/pact_decorator_spec.rb

@@ -2,13 +2,13 @@
 require 'pact_broker/api/decorators/pact_decorator'
 
 module PactBroker
-
   module Api
-
     module Decorators
-
       describe PactDecorator do
 
+        before do
+          allow_any_instance_of(PactDecorator).to receive(:templated_diff_url).and_return('templated-diff-url')
+        end
         let(:content_hash) {
           {
             'consumer' => {'name' => 'Consumer'},
@@ -105,6 +105,11 @@ module Decorators
             expect(subject[:_links][:'pb:publish-verification-results'][:href]).to match %r{http://example.org/.*/verification-results}
           end
 
+          it "includes a link to diff this pact version with another pact version" do
+            expect(subject[:_links][:'pb:diff'][:href]).to eq 'templated-diff-url'
+            expect(subject[:_links][:'pb:diff'][:templated]).to eq true
+          end
+
           it "includes a curie" do
             expect(subject[:_links][:curies]).to eq [{ name: "pb", href: "http://example.org/doc/{rel}", templated: true }]
           end
@@ -116,7 +121,6 @@ module Decorators
             end
           end
         end
-
       end
     end
   end

spec/lib/pact_broker/api/pact_broker_urls_spec.rb

@@ -4,8 +4,11 @@ module PactBroker
   module Api
     describe PactBrokerUrls do
 
+      # Regex find all the URL parameter names
+      # \/\{[^\}\s\[\(\.]+\}
+
       let(:base_url) { "http://example.org" }
-      let(:pact) { double('pact', consumer: consumer, provider: provider, consumer_version_number: "123") }
+      let(:pact) { double('pact', consumer: consumer, provider: provider, consumer_version_number: "123", pact_version_sha: "5hbfu") }
       let(:consumer) { double('pacticipant', name: "Foo") }
       let(:provider) { double('pacticipant', name: "Bar") }
       let(:verification) do
@@ -33,6 +36,12 @@ module Api
 
         it { is_expected.to eq "http://example.org/pacts/provider/Bar/consumer/Foo/pact-version/1234/verification-results/1/triggered-webhooks" }
       end
+
+      describe "templated_diff_url" do
+        subject { PactBrokerUrls.templated_diff_url(pact, base_url) }
+
+        it { is_expected.to eq "http://example.org/pacts/provider/Bar/consumer/Foo/pact-version/5hbfu/diff/pact-version/{pactVersion}" }
+      end
     end
   end
 end