Consider the test domain when generating asset_map_url

Closes QUIZ-10736
flag=none

Test Plan:
- Tail the canvas-live-events kinesis stream locally
- Do a course copy
- Validate the `content_migration_completed` event has a
  `resource_map_url` using `canvas.docker` as the domain
- Validate the `source_host` in the attachment matches
  this domain as well
- Simulate Canvas beta ENV locally (pair with weston for details)
- Do a course copy
-  Validate the `content_migration_completed` event has a
   `resource_map_url` that uses the configured beta domain
   as the domain in the file url
- Validate the `source_host` in the attachment matches this
  domain as well

Change-Id: Ic86b80f0e44d91c75b4fe2b661bad695aa3ab4a4
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/310021
Reviewed-by: Alex Slaughter <aslaughter@instructure.com>
QA-Review: Alex Slaughter <aslaughter@instructure.com>
Product-Review: Alex Slaughter <aslaughter@instructure.com>
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>

app/models/content_migration.rb

@@ -1184,10 +1184,15 @@ class ContentMigration < ActiveRecord::Base
 
   def asset_map_url(generate_if_needed: false)
     generate_asset_map if !asset_map_attachment && generate_if_needed
-    asset_map_attachment && file_download_url(asset_map_attachment, { verifier: asset_map_attachment.uuid,
-                                                                      download: "1",
-                                                                      download_frd: "1",
-                                                                      host: HostUrl.context_host(context) })
+    asset_map_attachment && file_download_url(
+      asset_map_attachment,
+      {
+        verifier: asset_map_attachment.uuid,
+        download: "1",
+        download_frd: "1",
+        host: context.root_account.domain(ApplicationController.test_cluster_name)
+      }
+    )
   end
 
   def generate_asset_map
@@ -1195,7 +1200,7 @@ class ContentMigration < ActiveRecord::Base
     return if data.nil?
 
     payload = {
-      "source_host" => source_course.root_account.domain,
+      "source_host" => source_course.root_account.domain(ApplicationController.test_cluster_name),
       "source_course" => source_course_id.to_s,
       "resource_mapping" => data
     }

spec/models/content_migration_spec.rb

@@ -1206,7 +1206,7 @@ describe ContentMigration do
     end
 
     it "returns a url to a file containing the asset map" do
-      expect_any_instance_of(Account).to receive(:domain).and_return("pineapple.edu")
+      allow(HostUrl).to receive(:default_host).and_return("pineapple.edu")
       url = @cm.asset_map_url(generate_if_needed: true)
       @cm.reload
       expect(url).to include "/files/#{@cm.asset_map_attachment.id}/download"
@@ -1219,5 +1219,45 @@ describe ContentMigration do
                              "assignments" => { @old.id.to_s => @new.id.to_s }
                            } })
     end
+
+    context "when not on a test cluster" do
+      let(:content_migration) do
+        @cm.update!(source_course: source_course)
+
+        @cm
+      end
+      let(:source_course) { course_factory }
+
+      before do
+        allow(ApplicationController).to receive(:test_cluster_name).and_return nil
+        allow(content_migration.context.root_account).to receive(:domain).and_return "pineapple.edu"
+      end
+
+      it "uses the 'production' host" do
+        expect(content_migration.context.root_account).to receive(:domain).with(nil)
+
+        content_migration.asset_map_url(generate_if_needed: true)
+      end
+    end
+
+    context "when on a test cluster" do
+      let(:content_migration) do
+        @cm.update!(source_course: source_course)
+
+        @cm
+      end
+      let(:source_course) { course_factory }
+
+      before do
+        allow(ApplicationController).to receive(:test_cluster_name).and_return "banana"
+        allow(content_migration.context.root_account).to receive(:domain).and_return "pineapple.edu"
+      end
+
+      it "uses the test host" do
+        expect(content_migration.context.root_account).to receive(:domain).with("banana")
+
+        content_migration.asset_map_url(generate_if_needed: true)
+      end
+    end
   end
 end