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ddd-ts-kit

ddd-ts-kit/purity-no-system-clock

Architecture id: purity/no-system-clock. Default severity: error in recommended, error in strict.

Applies to: domain/ and application/ of a context, tests excluded.

Why

Section titled “Why”

A rule that reads the clock gives a different answer at every run. Time is an input: the domain receives it, the application takes it from the Clock port, a test fixes it with FixedClock.

Reported

Section titled “Reported”
  • new Date() without argument
  • Date.now, Date()
  • performance.now, performance.timeOrigin
  • the same through globalThis, window, self or global

Incorrect:

const overdue = invoice.dueAt < new Date();
const started = Date.now();

Correct:

const overdue = invoice.isOverdue(this.clock.now());
const due = new Date(issuedAt.getTime() + 30 * DAY);

Details

Section titled “Details”

new Date(value) builds a date from data and is allowed.

Options

Section titled “Options”

None.

rules."purity/no-system-clock" in ddd-ts-kit.config.json set to off silences the rule, and // ddd-ts-kit-disable-next-line purity/no-system-clock -- <reason> silences one line, exactly as for ddd-ts-kit check.

Limits

Section titled “Limits”
  • A wrapper around the forbidden access (a helper of the platform that calls Date.now()) is not seen here; the layer rules stop the import of that helper.
  • A local declaration that shadows the global (const process = ...) is not reported.

With the CLI checker

Section titled “With the CLI checker”

ddd-ts-kit check looks for the same names with regular expressions. This rule is the authority: it knows a shadowed name from the global, and code from a string.