google conn error graceful handling

closes FOO-1388
flag=none

TEST PLAN:
  1) make google drive fail with timeouts
  2) try to list docs on assignments_controller
  3) do not get a 500, just fail to load them.

Change-Id: I7a70f643e3745a796b3a41baf8d832c275aebc83
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/255718
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Simon Williams <simon@instructure.com>
QA-Review: Simon Williams <simon@instructure.com>
Product-Review: Simon Williams <simon@instructure.com>

app/controllers/assignments_controller.rb

@@ -347,10 +347,18 @@ class AssignmentsController < ApplicationController
     # prevent masquerading users from accessing google docs
     if assignment.allow_google_docs_submission? && @real_current_user.blank?
       docs = {}
+      status_code = :ok
       begin
         docs = google_drive_connection.list_with_extension_filter(assignment.allowed_extensions)
-      rescue GoogleDrive::NoTokenError, Google::APIClient::AuthorizationError => e
+      rescue GoogleDrive::NoTokenError,
+             Google::APIClient::AuthorizationError => e
         Canvas::Errors.capture_exception(:oauth, e, :warn)
+        docs =  { errors: { base: t("Auth failure in connecting to Google Drive.") } }
+        status_code = :unauthorized
+      rescue GoogleDrive::ConnectionException => e
+        Canvas::Errors.capture_exception(:oauth, e, :warn)
+        docs =  { errors: { base: t("Unable to connect to Google Drive.") } }
+        status_code = :gateway_timeout
       rescue ArgumentError => e
         Canvas::Errors.capture_exception(:oauth, e)
       rescue => e
@@ -358,7 +366,7 @@ class AssignmentsController < ApplicationController
         raise e
       end
       respond_to do |format|
-        format.json { render json: docs.to_hash }
+        format.json { render json: docs.to_hash, status: status_code }
       end
     else
       error_object = {errors:

spec/controllers/assignments_controller_spec.rb

@@ -1762,17 +1762,28 @@ describe AssignmentsController do
   end
 
   describe "GET list_google_docs" do
-    it "passes errors through to Canvas::Errors" do
+    let(:connection){ double() }
+    let(:params){ {course_id: @course.id, id: @assignment.id} }
+
+    before(:each) do
       user_session(@teacher)
-      connection = double()
-      allow(connection).to receive(:list_with_extension_filter).and_raise(ArgumentError)
       allow(controller).to receive(:google_drive_connection).and_return(connection)
       allow_any_instance_of(Assignment).to receive(:allow_google_docs_submission?).and_return(true)
+    end
+
+    it "passes errors through to Canvas::Errors" do
+      allow(connection).to receive(:list_with_extension_filter).and_raise(ArgumentError)
       expect(Canvas::Errors).to receive(:capture_exception)
-      params = {course_id: @course.id, id: @assignment.id}
       get 'list_google_docs', params: params, format: 'json'
       expect(response.code).to eq("200")
     end
+
+    it "gives appropriate error code to connection errors" do
+      allow(connection).to receive(:list_with_extension_filter).and_raise(GoogleDrive::ConnectionException)
+      get 'list_google_docs', params: params, format: 'json'
+      expect(response.code).to eq("504")
+      expect(response.body).to include("Unable to connect to Google Drive")
+    end
   end
 
 end