Migration tests

Verify first, write last ... and always test!

Goal

Write tests for a simple storage migration.

Use cases

Testing a migration module inside a pallet.

Overview

When writing a runtime migration module it is important to test it to avoid any critical issues caused by mangling storage items. This guide provides a walk through of the tests to include for a simple storage migration of a single pallet, using the Nicks pallet migration from the Basic Storage Migration guide as a reference.

Steps

1. Write mock runtime

Refer to this guide to learn how to set up the dependencies for your test environment.

2. Specify unit tests

Derive the different tests that need to be included based on your pallet's functions.

For the Nicks pallet migration we need:

• fn kill_name_should_work()
• fn force_name_should_work()
• fn normal_operation_should_work()
• fn error_catching_should_work()

Using asset_noop!(...), assert_ok!(...) and assert_eq!(...), constructing one of these tests looks like this:

#[test]

fn normal_operation_should_work() {

new_test_ext().execute_with(|| {

assert_ok!(Nicks::set_name(Origin::signed(1), b"Gav".to_vec(), None));

assert_eq!(Balances::reserved_balance(1), 2);

assert_eq!(Balances::free_balance(1), 8);

assert_eq!(<NameOf<Test>>::get(1).unwrap().0.first, b"Gav".to_vec());

assert_ok!(Nicks::set_name(Origin::signed(1), b"Gavin".to_vec(), None));

assert_eq!(Balances::reserved_balance(1), 2);

assert_eq!(Balances::free_balance(1), 8);

assert_eq!(<NameOf<Test>>::get(1).unwrap().0.first, b"Gavin".to_vec());

assert_ok!(Nicks::clear_name(Origin::signed(1)));

assert_eq!(Balances::reserved_balance(1), 0);

assert_eq!(Balances::free_balance(1), 10);

});

}

Examples

• Migrating the Nicks pallet

Resources

How-to guides

• Migration steps
• Nicks migration

Other

• Fork-off Substrate tool