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Testing

Move has a built-in testing framework that lets you write unit tests alongside your code. Tests are functions marked with the #[test] attribute, excluded from the published bytecode, and run with the sui move test command. The framework supports expected failures via #[expected_failure] and test-only helpers via #[test_only].

module book::testing;

#[test_only]
use std::unit_test::assert_eq;

// test functions take no arguments and return nothing
#[test]
fun simple_test() {
    let sum = 2 + 2;
    assert_eq!(sum, 4);
}

#[test, expected_failure(abort_code = 0)]
fun test_fail() {
    abort 0
}

A test passes if it runs to completion and fails if it aborts - which is exactly what the assert_eq! macro does when its two values differ. For arbitrary conditions there is the more general assert! macro; both are the workhorses of Move tests. The second test above inverts the outcome: #[expected_failure(abort_code = 0)] makes the test pass only if it aborts with the given code, which is the way to test error conditions.

Test-Only Code​

The #[test_only] attribute marks a module member - or an entire module - as compiled only for tests. Test helpers, mock constructors, and imports like the std::unit_test import above are marked this way: the published bytecode stays free of testing machinery, while tests get access to everything they need, including things the public API deliberately does not expose.

Explore More​

This page only scratches the surface. The dedicated Testing chapter walks through test scenarios, coverage reports, gas profiling, working with system objects, and best practices for writing tests you can actually trust in production.

What's Next​

This page concludes the Move Basics chapter. You can now define modules and custom types, control whether values can be copied or discarded, pass them around by reference or by value, write logic with pattern matching, abstract it with generics and macros - and test all of it. What we have set aside so far is what makes Move on Sui special: the storage model. The Object Model chapter picks up exactly there - it introduces objects, the Move structs that become onchain assets, and the chapters after it show how to store, own, and transfer them.

Further Reading​

llms.txt