std/testing

Testing helpers built on the assertion runtime.

testing.check(expr) uses the same assertion machinery as assert expr, but returns Result<Subject, AssertionFailure> instead of propagating the failure. It is useful when tests need to inspect or render a failure value.

Import with import std/testing.

Exports

Types

• Clock

enum Clock

enum Clock {
    System
    Virtual
}

Which clock a tests group runs under, declared as clock Clock.Virtual or clock Clock.System beside the group’s boot and setup.

Tests that wait are slow when they pass and unreliable when the machine is busy. A virtual clock jumps forward whenever every task in the test is blocked, so waiting costs nothing and takes the same path every run, and work that can never finish is reported as a deadlock rather than hanging.

It is not the default, because a virtual clock changes behaviour: waiting on something outside the program (reading input, a real network call) never lets the clock move and is reported as a deadlock; background work still running when a test ends is an error rather than something that carries into the next test; and Instant.now starts at midnight on 1 January 2000.

Groups inherit the declaration from an enclosing group, so System is how a nested group that talks to the outside world opts back out.

Variants

• System

  The real clock. The default, and what every test used before this existed.

• Virtual

  A clock that only advances when every task in the test is blocked.

Clock.inspect

fn inspect(value: Clock): String

impl Debug.inspect

testing.check

fn check<T>(subject: T): Result<T, AssertionFailure>

Returns Ok(subject) when subject would pass assert; otherwise returns Err(failure) with the same structured assertion context used by nomi test.

Interactive Tests

refute testing.check(1 == 2)