Introduce Project#builds_for(build_name, ref = 'HEAD'):

So that we could find the particular builds according to
build_name and ref. It would be used to find the latest
build artifacts from a particular branch or tag.

app/models/commit_status.rb

@@ -16,7 +16,13 @@ class CommitStatus < ActiveRecord::Base
 
   alias_attribute :author, :user
 
-  scope :latest, -> { where(id: unscope(:select).select('max(id)').group(:name, :commit_id)) }
+  scope :latest, -> do
+    id = unscope(:select).
+           select("max(#{table_name}.id)").
+           group(:name, :commit_id)
+
+    where(id: id)
+  end
   scope :retried, -> { where.not(id: latest) }
   scope :ordered, -> { order(:name) }
   scope :ignored, -> { where(allow_failure: true, status: [:failed, :canceled]) }

app/models/project.rb

@@ -429,6 +429,14 @@ class Project < ActiveRecord::Base
     repository.commit(id)
   end
 
+  def builds_for(build_name, ref = 'HEAD')
+    sha = commit(ref).sha
+
+    builds.joins(:pipeline).
+      merge(Ci::Pipeline.where(sha: sha)).
+      where(name: build_name)
+  end
+
   def merge_base_commit(first_commit_id, second_commit_id)
     sha = repository.merge_base(first_commit_id, second_commit_id)
     repository.commit(sha) if sha

spec/models/build_spec.rb

@@ -673,7 +673,7 @@ describe Ci::Build, models: true do
     context 'when build is running' do
       before { build.run! }
 
-      it 'should return false' do
+      it 'returns false' do
         expect(build.retryable?).to be false
       end
     end
@@ -681,9 +681,17 @@ describe Ci::Build, models: true do
     context 'when build is finished' do
       before { build.success! }
 
-      it 'should return true' do
+      it 'returns true' do
         expect(build.retryable?).to be true
       end
     end
   end
+
+  describe 'Project#builds_for' do
+    it 'returns builds from ref and build name' do
+      latest_build = project.builds_for(build.name, 'HEAD').latest.first
+
+      expect(latest_build.id).to eq(build.id)
+    end
+  end
 end