feat: add endpoint to return latest pact for consumer, provider and c…

…onsumer branch

lib/pact_broker/api.rb

@@ -65,6 +65,7 @@ def self.build_api(application_context = PactBroker::ApplicationContext.default_
         # Latest pacts
         add ["pacts", "provider", :provider_name, "consumer", :consumer_name, "latest"], Api::Resources::LatestPact, {resource_name: "latest_pact_publication"}
         add ["pacts", "provider", :provider_name, "consumer", :consumer_name, "latest", :tag], Api::Resources::LatestPact, {resource_name: "latest_tagged_pact_publication"}
+        add ["pacts", "provider", :provider_name, "consumer", :consumer_name, "branch", :branch_name, "latest"], Api::Resources::LatestPact, {resource_name: "latest_pact_publication_for_branch"}
         add ["pacts", "provider", :provider_name], Api::Resources::ProviderPacts, {resource_name: "provider_pact_publications"}
         add ["pacts", "provider", :provider_name, "tag", :tag], Api::Resources::ProviderPacts, {resource_name: "tagged_provider_pact_publications"}
         add ["pacts", "provider", :provider_name, "consumer", :consumer_name, "latest-untagged"], Api::Resources::LatestPact, {resource_name: "latest_untagged_pact_publication", tag: :untagged}

lib/pact_broker/pacts/pact_publication_dataset_module.rb

@@ -132,10 +132,14 @@ def for_branch_heads(branch_name)
           .remove_overridden_revisions_from_complete_query
       end
 
+      # The pact that belongs to the branch head.
+      # May return nil if the branch head does not have a pact published for it.
       def latest_for_consumer_branch(branch_name)
         for_branch_heads(branch_name)
       end
 
+      # The latest pact that belongs to a version on the specified branch (might not be the version that is the branch head)
+      # Always returns a pact, if any pacts exist for this branch.
       def old_latest_for_consumer_branch(branch_name)
         branch_versions_join = {
           Sequel[:pact_publications][:consumer_version_id] => Sequel[:branch_versions][:version_id]
@@ -148,7 +152,7 @@ def old_latest_for_consumer_branch(branch_name)
 
         max_orders = join(:branch_versions, branch_versions_join)
                       .join(:branches, branches_join)
-                      .select_group(:consumer_id, :provider_id, Sequel[:branches][:name].as(:branch_name))
+                      .select_group(Sequel[:pact_publications][:consumer_id], Sequel[:pact_publications][:provider_id], Sequel[:branches][:name].as(:branch_name))
                       .select_append{ max(consumer_version_order).as(latest_consumer_version_order) }
 
         max_join = {

lib/pact_broker/pacts/repository.rb

@@ -200,7 +200,7 @@ def find_latest_pacts
           .sort
       end
 
-      def find_latest_pact(consumer_name, provider_name, tag = nil)
+      def find_latest_pact(consumer_name, provider_name, tag = nil, branch_name = nil)
         query = scope_for(PactPublication)
           .eager_for_domain_with_content
           .select_all_qualified
@@ -211,6 +211,8 @@ def find_latest_pact(consumer_name, provider_name, tag = nil)
           query = query.untagged
         elsif tag
           query = query.for_consumer_version_tag_all_revisions(tag)
+        elsif branch_name
+          query = query.old_latest_for_consumer_branch(branch_name)
         end
         query.latest_by_consumer_version_order.all.collect(&:to_domain_with_content)[0]
       end

lib/pact_broker/pacts/service.rb

@@ -23,7 +23,7 @@ module Service
       extend SquashPactsForVerification
 
       def find_latest_pact params
-        pact_repository.find_latest_pact(params[:consumer_name], params[:provider_name], params[:tag])
+        pact_repository.find_latest_pact(params[:consumer_name], params[:provider_name], params[:tag], params[:branch_name])
       end
 
       def search_for_latest_pact params

spec/features/get_latest_pact_for_branch.rb

@@ -0,0 +1,22 @@
+describe "retrieving the latest pact for a branch" do
+  let(:path) { "/pacts/provider/Provider/consumer/Consumer/branch/main/latest" }
+  let(:json_response_body) { JSON.parse(subject.body, symbolize_names: true) }
+
+  subject { get(path)  }
+
+  before do
+    td.create_consumer("Consumer")
+      .create_provider("Provider")
+      .create_consumer_version("1", branch: "main")
+      .create_pact
+      .create_consumer_version("2", branch: "main")
+      .create_pact
+      .create_consumer_version("3", branch: "foo")
+      .create_pact
+      .create_consumer_version("4", branch: "main")
+  end
+
+  it "returns the latest pact for the branch" do
+    expect(json_response_body[:_links][:self][:href]).to end_with("2")
+  end
+end

spec/lib/pact_broker/pacts/repository_spec.rb

@@ -965,6 +965,26 @@ module Pacts
             end
           end
         end
+
+        context "with a branch specified" do
+          before do
+            td.create_consumer("Consumer")
+              .create_provider("Provider")
+              .create_consumer_version("1.0.0", branch: "main")
+              .create_pact
+              .create_consumer_version("1.2.3", branch: "main")
+              .create_pact
+              .create_consumer_version("2.3.4", branch: "main")
+              .create_consumer_version("4", branch: "foo")
+              .create_pact
+          end
+
+          subject { Repository.new.find_latest_pact("Consumer", "Provider", nil, "main") }
+
+          it "returns the latest pact that belongs to a version on the specified branch" do
+            expect(subject.consumer_version.number).to eq("1.2.3")
+          end
+        end
       end
 
       describe "search_for_latest_pact" do