simplify fetching of commit

app/models/gpg_signature.rb

@@ -5,4 +5,8 @@ class GpgSignature < ActiveRecord::Base
   validates :commit_sha, presence: true
   validates :project, presence: true
   validates :gpg_key_primary_keyid, presence: true
+
+  def commit
+    project.commit(commit_sha)
+  end
 end

lib/gitlab/gpg/invalid_gpg_signature_updater.rb

@@ -10,9 +10,7 @@ module Gitlab
           .where(valid_signature: false)
           .where(gpg_key_primary_keyid: @gpg_key.primary_keyid)
           .find_each do |gpg_signature|
-            raw_commit = Gitlab::Git::Commit.find(gpg_signature.project.repository, gpg_signature.commit_sha)
-            commit = ::Commit.new(raw_commit, gpg_signature.project)
-            Gitlab::Gpg::Commit.new(commit).update_signature!(gpg_signature)
+            Gitlab::Gpg::Commit.new(gpg_signature.commit).update_signature!(gpg_signature)
           end
       end
     end

spec/lib/gitlab/gpg/invalid_gpg_signature_updater_spec.rb

@@ -29,7 +29,7 @@ RSpec.describe Gitlab::Gpg::InvalidGpgSignatureUpdater do
     end
 
     before do
-      allow(Gitlab::Git::Commit).to receive(:find).with(kind_of(Repository), commit_sha).and_return(raw_commit)
+      allow_any_instance_of(GpgSignature).to receive(:commit).and_return(commit)
     end
 
     context 'gpg signature did not have an associated gpg key' do

spec/models/gpg_signature_spec.rb

@@ -12,4 +12,17 @@ RSpec.describe GpgSignature do
     it { is_expected.to validate_presence_of(:project) }
     it { is_expected.to validate_presence_of(:gpg_key_primary_keyid) }
   end
+
+  describe '#commit' do
+    it 'fetches the commit through the project' do
+      commit_sha = '0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33'
+      project = create :project
+      commit = create :commit, project: project
+      gpg_signature = create :gpg_signature, commit_sha: commit_sha
+
+      expect_any_instance_of(Project).to receive(:commit).with(commit_sha).and_return(commit)
+
+      gpg_signature.commit
+    end
+  end
 end