Test Fixtures

Generate a deterministic set of fake user records using the Faker provider and range + map.

Source

examples/test-fixtures/main.rank

/// Generates deterministic test fixture data using the Faker provider.
/// Shows Rand::seed for reproducibility, range + map to produce N records,
/// and typed schemas to validate the generated shape.

use faker::{ Generate, UUID, Person, Int }
use faker::types::{ Spec }
use std::list::{ range }
use std::collections::{ map }

User = Object {
  id: string,
  name: string,
  age: number,
}

seed = 42
count = 10

spec: Spec<User> = {
  id: UUID {},
  name: Person { sex: `female` },
  age: Int { min: 18, max: 65 },
}

users: [User] = range(count)
  |> map(|_, ctx| Generate<User> {
       spec,
       seed,
       itemKey: ctx.index,
       locale: `en_US`,
     })

pub main = || {
  count: count,
  users: users,
}

Output

{
  "count": 10,
  "users": [
    { "id": "a1b2c3d4-...", "name": "Alice Johnson", "age": 34 },
    { "id": "e5f6a7b8-...", "name": "Maria Garcia", "age": 27 },
    ...
  ]
}

The output is identical on every run because seed and itemKey together fully determine each generated value.

Key concepts

• Spec<T> — a typed descriptor that pairs each field of T with a Faker generator. The compiler checks that every field is covered.
• Generate<T> — evaluates a Spec<T> with a seed and item key. Different itemKey values produce different records; the same key always produces the same record.
• range(count) |> map — generates indices [0, 1, ..., count-1] and maps each to a Generate call, passing ctx.index as the itemKey.
• ctx parameter — the second argument to map callbacks is an iterator context with index, size, isFirst, and isLast.

Run it

rank examples/test-fixtures

Requires the faker provider package. See the Faker Provider docs for installation.