Added evidence_sha to Release API entity

Updated Release API and docs.
Updated Release model.
Added tests accordingly.

app/models/release.rb

@@ -73,6 +73,10 @@ class Release < ApplicationRecord
     self.read_attribute(:name) || tag
   end
 
+  def evidence_sha
+    evidence&.summary_sha
+  end
+
   private
 
   def actual_sha

doc/api/releases/index.md

@@ -87,6 +87,7 @@ Example response:
       ],
       "commit_path":"/root/awesome-app/commit/588440f66559714280628a4f9799f0c4eb880a4a",
       "tag_path":"/root/awesome-app/-/tags/v0.11.1",
+      "evidence_sha":"760d6cdfb0879c3ffedec13af470e0f71cf52c6cde4d",
       "assets":{
          "count":6,
          "sources":[
@@ -154,6 +155,7 @@ Example response:
          "committer_email":"admin@example.com",
          "committed_date":"2019-01-03T01:53:28.000Z"
       },
+      "evidence_sha":"760d6cdfb0879c3ffedec13af470e0f71cf52c6cde4d",
       "assets":{
          "count":4,
          "sources":[
@@ -265,6 +267,7 @@ Example response:
    ],
    "commit_path":"/root/awesome-app/commit/588440f66559714280628a4f9799f0c4eb880a4a",
    "tag_path":"/root/awesome-app/-/tags/v0.11.1",
+   "evidence_sha":"760d6cdfb0879c3ffedec13af470e0f71cf52c6cde4d",
    "assets":{
       "count":4,
       "sources":[
@@ -385,6 +388,7 @@ Example response:
    ],
    "commit_path":"/root/awesome-app/commit/588440f66559714280628a4f9799f0c4eb880a4a",
    "tag_path":"/root/awesome-app/-/tags/v0.11.1",
+   "evidence_sha":"760d6cdfb0879c3ffedec13af470e0f71cf52c6cde4d",
    "assets":{
       "count":5,
       "sources":[
@@ -491,6 +495,7 @@ Example response:
    ],
    "commit_path":"/root/awesome-app/commit/588440f66559714280628a4f9799f0c4eb880a4a",
    "tag_path":"/root/awesome-app/-/tags/v0.11.1",
+   "evidence_sha":"760d6cdfb0879c3ffedec13af470e0f71cf52c6cde4d",
    "assets":{
       "count":4,
       "sources":[
@@ -573,6 +578,7 @@ Example response:
    },
    "commit_path":"/root/awesome-app/commit/588440f66559714280628a4f9799f0c4eb880a4a",
    "tag_path":"/root/awesome-app/-/tags/v0.11.1",
+   "evidence_sha":"760d6cdfb0879c3ffedec13af470e0f71cf52c6cde4d",
    "assets":{
       "count":4,
       "sources":[

lib/api/entities.rb

@@ -1315,6 +1315,7 @@ module API
       expose :milestones, using: Entities::Milestone, if: -> (release, _) { release.milestones.present? }
       expose :commit_path, expose_nil: false
       expose :tag_path, expose_nil: false
+      expose :evidence_sha, if: -> (release, _) { release.evidence.present? }
       expose :assets do
         expose :assets_count, as: :count do |release, _|
           assets_to_exclude = can_download_code? ? [] : [:sources]

spec/models/release_spec.rb

@@ -141,4 +141,25 @@ RSpec.describe Release do
       end
     end
   end
+
+  describe '#evidence_sha' do
+    let!(:release) { create(:release) }
+
+    before do
+      CreateEvidenceWorker.new.perform(release.id)
+    end
+
+    context 'when a release was created before evidence collection existed' do
+      it 'is nil' do
+        allow(release).to receive(:evidence).and_return(nil)
+
+        expect(release.evidence_sha).to be_nil
+      end
+    end
+    context 'when a release was created with evidence collection' do
+      it 'returns the summary sha' do
+        expect(release.evidence_sha).to eq(release.evidence.summary_sha)
+      end
+    end
+  end
 end