Refactor paginated_check_runs to use lazy pagination

Author: katestud

app/models/shipit/commit.rb

@@ -168,28 +168,26 @@ def create_status_from_github!(github_status)
       end
     end
 
-    def paginated_check_runs
+    def paginated_check_runs(&block)
       response = stack.handle_github_redirections do
         stack.github_api.check_runs(github_repo_name, sha, per_page: 100)
       end
 
-      return response if stack.github_api.last_response.rels[:next].nil?
+      yield response.check_runs
 
-      loop do
+      until stack.github_api.last_response.rels[:next].nil?
         page = stack.handle_github_redirections do
           stack.github_api.get(stack.github_api.last_response.rels[:next].href)
         end
-        response.check_runs.concat(page.check_runs)
-        break if stack.github_api.last_response.rels[:next].nil?
+        yield page.check_runs
       end
-
-      response
     end
 
     def refresh_check_runs!
-      response = paginated_check_runs
-      response.check_runs.each do |check_run|
-        create_or_update_check_run_from_github!(check_run)
+      paginated_check_runs do |check_runs|
+        check_runs.each do |check_run|
+          create_or_update_check_run_from_github!(check_run)
+        end
       end
     end
 

test/models/commits_test.rb

@@ -367,6 +367,76 @@ class CommitsTest < ActiveSupport::TestCase
       assert_equal 'success', @commit.check_runs.first.state
     end
 
+    test "refresh_check_runs! handles paginated responses from github" do
+      # First page check runs
+      check_run_1 = mock(
+        id: 111_111_111_111_111,
+        name: 'Test suite 1',
+        conclusion: 'success',
+        details_url: 'https://example.com/details/1',
+        html_url: 'https://example.com/run/1',
+        output: mock(
+          title: 'Tests build 1 ran successfully'
+        ),
+        completed_at: Time.now,
+        started_at: Time.now - 1.minute
+      )
+      check_run_2 = mock(
+        id: 222_222_222_222_222,
+        name: 'Test suite 2',
+        conclusion: 'failure',
+        details_url: 'https://example.com/details/2',
+        html_url: 'https://example.com/run/2',
+        output: mock(
+          title: 'Tests build 2 failed'
+        ),
+        completed_at: Time.now,
+        started_at: Time.now - 2.minutes
+      )
+
+      # Second page check runs
+      check_run_3 = mock(
+        id: 333_333_333_333_333,
+        name: 'Test suite 3',
+        conclusion: 'neutral',
+        details_url: 'https://example.com/details/3',
+        html_url: 'https://example.com/run/3',
+        output: mock(
+          title: 'Tests build 3 skipped'
+        ),
+        completed_at: Time.now,
+        started_at: Time.now - 3.minutes
+      )
+
+      next_link = mock(href: 'https://api.github.com/repos/test/repo/check-runs?page=2')
+      first_response = stub(rels: { next: next_link })
+      first_page_data = mock(check_runs: [check_run_1, check_run_2])
+
+      second_response = stub(rels: {})
+      second_page_data = mock(check_runs: [check_run_3])
+
+      Shipit.github.api.expects(:check_runs).with(@stack.github_repo_name, @commit.sha, per_page: 100).returns(first_page_data)
+      Shipit.github.api.expects(:last_response).returns(first_response).twice
+      Shipit.github.api.expects(:get).with(next_link.href).returns(second_page_data)
+      Shipit.github.api.expects(:last_response).returns(second_response)
+
+      assert_difference -> { @commit.check_runs.count }, 3 do
+        @commit.refresh_check_runs!
+      end
+
+      check_1 = @commit.check_runs.find_by(github_id: 111_111_111_111_111)
+      assert_not_nil check_1
+      assert_equal 'success', check_1.state
+
+      check_2 = @commit.check_runs.find_by(github_id: 222_222_222_222_222)
+      assert_not_nil check_2
+      assert_equal 'error', check_2.state
+
+      check_3 = @commit.check_runs.find_by(github_id: 333_333_333_333_333)
+      assert_not_nil check_3
+      assert_equal 'pending', check_3.state
+    end
+
     test "#creating a commit update the undeployed_commits_count" do
       walrus = shipit_users(:walrus)
       assert_equal 2, @stack.undeployed_commits_count