Test Values

The values a test writes. The testing skill owns the suite's structure, assertions and mocking; this skill owns every literal in it, because a value chosen per file is the thing that drifts — one suite's typed calendar date beside another's typed epoch beside a third's new Date() — and the drift is what makes a reviewer stop to ask whether the value means something. A canonical value means nothing, and says so.

Settled — do not re-propose

• A typed date or time literal — "1970-01-01", a "YYYY-MM-DDTHH:mm:ssZ" stamp of some real year, new Date("1970-01-02"). Each file spells the epoch its own way, and a format read off one string (date-only, seconds, milliseconds, offset) is asserted against another's. The epoch is computed, never typed (references/dates-and-times.md).
• Exporting the epoch from @esposter/shared. new Date(0) and Temporal.Instant.fromEpochMilliseconds(0) are already the computed spelling, and the one verbose one — the plain date — is read by genshin-persona alone, which a workspace import cannot reach (its plugin cache runs a frozen npm ci; apps/web/content/docs/infra/claude-interface/persona-plugin.md). An export no reachable package names is what scripts/src/workspace/sharedExportConsumers.test.ts reports, so each package that reads a plain-date epoch declares it once (references/dates-and-times.md); two reachable packages doing so is the trigger to hoist it.
• A calendar date from any year but 1970 — a fixture dated the year the test was written, a "recent" date, a date picked for its month name. Only the epoch has a meaning a reader can name; every other date reads as data someone chose, and the reader checks why. A shape test that needs its parts to differ stays in the epoch's own days (references/dates-and-times.md).
• A semantic name for a value the code never reads — "room-1", "test-id", "logo.png", "helper.cjs", "nested". It reads as meaning something, and the next reader has to check whether it does ("Every string literal passes one of three checks", on this page).
• Prose as a body, title or note — an invented sentence a human would type. The code matches a substring or stores a blob; the sentence is decoration and is what gets copied into the next suite as if it mattered.
• A per-file copy of a value production owns — a sentinel, marker, prefix, filename or sizing formula restated in the suite. It stays green while asserting the wrong thing after the source moves (references/shared-data.md).
• A realistic corpus of exported artifacts — a folder of real maps, captured payloads or documents, one fixture per production case. Realism is not coverage: such a corpus carries a handful of distinguishable shapes between all its files, so nearly every one of them re-parses the branches an earlier one already reached, and the corpus and its committed snapshots cost orders of magnitude more repository and runtime than the shapes do (references/fixture-corpora.md).
• A lint rule for a mocked error's message. Two rejections a case tells apart are "a" and "b", unicorn/error-message already owns the empty one, and a message the code classifies keeps the shape it reads, so what makes a message prose is a judgement about the case rather than a shape of the literal — the test-values sweep reads it (references/canonical-values.md).
• Loosening the assertion because the output is not minimal — parsing a rendered block to read three attributes out of it, or a toContain over a markup string. A static output is toStrictEqualed whole, like a snapshot; when that expectation reads as data someone chose — an anchor carrying padding, a font and a radius the case never reads — the producer is what is over-specified, and it is trimmed to what the behaviour owes (the href, the label, the one colour a constant names) until the whole output is the least value.

The goal: the least value that still distinguishes

Every value a test writes is the least one that tells apart what the test reads; when a case needs two to differ, one moves by one step in the one part the case reads, and a value whose source is under test keeps a decoy one step away (references/least-value.md).

Canonical values

• Strings "", then " "; "a" only where a space trims away. Numbers 0, 0.1, -1. Booleans as the pair true/false, and "true"/"false" where the value under test is a string.
• Ids: the nonexistent one is "-1", a real one crypto.randomUUID(). Entity fields take the field's name as the value.
• Paths are TEST_FILENAME / TEST_DIR from the nearest constants.test.ts; a mock's error is new Error(" "); a value a parser reads by shape stays whole with its skipped parts canonical.
• Each kind in full, with the exceptions: references/canonical-values.md.

Fixture corpora

One file per shape the code under test can tell apart, each the least content that carries it, named after its shape (references/fixture-corpora.md).

Dates and times

Every date is computed from the epoch; none is typed — new Date(0), a later one the epoch plus a Temporal duration, the clock pinned with vi.useFakeTimers({ now: 0 }). The typed half is test-values/no-typed-date; every form and the shape exception are references/dates-and-times.md.

Every string literal passes one of three checks

It is the value under test, or a canonical value, or an existing describe-scope constant or helper in the file. Anything else is decoration the code never inspects and does not go in. A token the code does inspect is hoisted with its body so the two cannot drift: const filteredWord = "spam"; const filteredMessage = `<p>${filteredWord}</p>`;.

Shared data — declare once, import what production owns

• Never repeat a literal or object — two readers make it one describe-scope const; a value used once stays inline.
• Import what production owns — a sentinel, marker, prefix, filename or formula the source declares is imported, never mirrored.
• Grep before adding a fixture: a literal a sibling uses inline is an undeclared constant.
• base* plus spread for near-identical objects, create* helpers for envelopes and entities, and per-test state as a let set in beforeEach: references/shared-data.md.

Reference pages

• references/least-value.md — when a case needs two values to differ, or a value seems to need more than the canonical one.
• references/canonical-values.md — when a literal's canonical form is not settled by the one-line list: paths, thrown errors, parsed values, padded streams, descriptions.
• references/fixture-corpora.md — when a suite reads a folder of fixture files, or a corpus is being trimmed.
• references/dates-and-times.md — when a test writes a Date, a Temporal value or a date string, or the code reads the clock.
• references/shared-data.md — when a value is shared between tests, a fixture helper is built, or production already declares the value.