log all sis errors and warnings to a file

refs CNVS-37717

test plan
 - run sis import that would generate errors
 - in console it should have an errors_attachment
 - the attachment should contain all the errors

Change-Id: I8e76d29395047b1ee743e42394432baea27d7c3a
Reviewed-on: https://gerrit.instructure.com/116522
Tested-by: Jenkins
Reviewed-by: Tyler Pickett <tpickett@instructure.com>
QA-Review: Tucker McKnight <tmcknight@instructure.com>
Product-Review: Rob Orton <rob@instructure.com>

app/models/sis_batch.rb

@@ -24,6 +24,7 @@ class SisBatch < ActiveRecord::Base
   serialize :processing_errors, Array
   serialize :processing_warnings, Array
   belongs_to :attachment
+  belongs_to :errors_attachment, class_name: 'Attachment'
   belongs_to :generated_diff, class_name: 'Attachment'
   belongs_to :batch_mode_term, class_name: 'EnrollmentTerm'
   belongs_to :user
@@ -416,9 +417,28 @@ class SisBatch < ActiveRecord::Base
     Setting.get('sis_batch_max_messages', '1000').to_i
   end
 
+  def write_warnings_and_errors_to_file
+    error_count = processing_errors&.size || 0
+    warning_count = processing_warnings&.size || 0
+    return unless error_count > 0 || warning_count > 0
+    temp = Tempfile.open([self.global_id.to_s + '_processing_warnings_and_errors', '.csv'])
+    file = temp.path
+    temp.close!
+    CSV.open(file, "w") do |csv|
+      processing_warnings.each {|row| csv << row}
+      processing_errors.each {|row| csv << row}
+    end
+    self.errors_attachment = SisBatch.create_data_attachment(
+      self,
+      Rack::Test::UploadedFile.new(file, 'csv', true),
+      t("sis_errors_attachment_%{id}", id: self.id)
+    )
+  end
+
   def limit_size_of_messages
     max_messages = SisBatch.max_messages
     %w[processing_warnings processing_errors].each do |field|
+      write_warnings_and_errors_to_file
       if self.send("#{field}_changed?") && (self.send(field).try(:size) || 0) > max_messages
         limit_message = case field
                         when "processing_warnings"

db/migrate/20170621223249_add_processing_errors_attachment_to_sis_batch.rb

@@ -0,0 +1,26 @@
+#
+# Copyright (C) 2017 - present Instructure, Inc.
+#
+# This file is part of Canvas.
+#
+# Canvas is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, version 3 of the License.
+#
+# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see <http://www.gnu.org/licenses/>.
+
+class AddProcessingErrorsAttachmentToSisBatch < ActiveRecord::Migration[5.0]
+  tag :predeploy
+
+  def change
+    add_column :sis_batches, :errors_attachment_id, :integer, :limit => 8
+    add_foreign_key :sis_batches, :attachments, column: :errors_attachment_id
+    add_index :sis_batches, :errors_attachment_id
+  end
+end

spec/models/sis_batch_spec.rb

@@ -475,6 +475,15 @@ s2,test_1,section2,active},
     expect(batch.processing_errors.last).to eq ['', 'There were 3 more errors']
   end
 
+  it "should write warnings/errors to a file" do
+    batch = @account.sis_batches.create!
+    batch.processing_warnings = [ ['testfile.csv', 'test warning'] ] * 3
+    batch.processing_errors = [ ['testfile.csv', 'test error'] ] * 3
+    batch.save!
+    error_file = batch.errors_attachment
+    expect(CSV.parse(error_file.open).map.to_a.size).to eq 6
+  end
+
   context "csv diffing" do
     it "should skip diffing if previous diff not available" do
       SIS::CSV::DiffGenerator.any_instance.expects(:generate).never