LS1009: Domain Reads a Nondeterministic Value

LS1009 is a compiler check that reports a read of the clock, randomness, or a new identifier in Domain, the project that holds business rules, because such reads answer differently on each call and tests cannot repeat them. This page states what the rule reports, where the warning sits, and how to pass the value in as an argument.

Reference#

What the rule enforces#

LS1009 enforces Pass nondeterministic values into Domain (litespec/backend/domain#pass-nondeterministic-values-into-domain). It runs in Domain only. Its category is LiteSpec.Domain. It reports a warning and is enabled by default, as the Analyzers overview describes.

What the rule reports#

The rule reports reads of DateTime.Now, DateTime.UtcNow, DateTime.Today, DateTimeOffset.Now, DateTimeOffset.UtcNow, TimeProvider.System, Environment.TickCount, Environment.TickCount64, Random.Shared, Guid.NewGuid, Guid.CreateVersion7, Stopwatch.GetTimestamp, Stopwatch.StartNew, any RandomNumberGenerator call, and new Random(). The diagnostic sits on the member name, on the invoked method name, or on the type in new Random().

Failing example#

public DateTime Stamp()
{
    return DateTime.UtcNow;
}

Passing example#

public DateTime Stamp(DateTime utcNow)
{
    return utcNow;
}

How to fix#

Pass time, randomness, and new identifiers in as arguments from the caller, and create version 7 identifiers with Guid.CreateVersion7 in the calling layer.

Notes#

What the rule ignores#

The rule does not report values passed in as arguments, deterministic members such as DateTime.MinValue, Guid.Empty, or Guid.Parse, instance calls on an injected clock such as clock.GetUtcNow(), or names inside nameof. It does not run outside Domain.