MM-21898 - Part 1: Generate and use an interface instead of *A… (#13840)

* Generate and use an interface instead of *App

app/permissions_test.go

@@ -255,11 +255,11 @@ func TestImportPermissions_schemeDeletedOnRoleFailure(t *testing.T) {
 
 func withMigrationMarkedComplete(th *TestHelper, f func()) {
 	// Mark the migration as done.
-	th.App.Srv.Store.System().PermanentDeleteByName(model.MIGRATION_KEY_ADVANCED_PERMISSIONS_PHASE_2)
-	th.App.Srv.Store.System().Save(&model.System{Name: model.MIGRATION_KEY_ADVANCED_PERMISSIONS_PHASE_2, Value: "true"})
+	th.App.Srv().Store.System().PermanentDeleteByName(model.MIGRATION_KEY_ADVANCED_PERMISSIONS_PHASE_2)
+	th.App.Srv().Store.System().Save(&model.System{Name: model.MIGRATION_KEY_ADVANCED_PERMISSIONS_PHASE_2, Value: "true"})
 	// Un-mark the migration at the end of the test.
 	defer func() {
-		th.App.Srv.Store.System().PermanentDeleteByName(model.MIGRATION_KEY_ADVANCED_PERMISSIONS_PHASE_2)
+		th.App.Srv().Store.System().PermanentDeleteByName(model.MIGRATION_KEY_ADVANCED_PERMISSIONS_PHASE_2)
 	}()
 	f()
 }