#consistent-each-for

#Configuration

import { defineConfig, rstestPlugin } from '@rslint/core';

export default defineConfig([
  rstestPlugin.configs.recommended,
  {
    rules: {
      'rstest/consistent-each-for': 'error',
    },
  },
]);

#Rule Details

Rstest offers two ways to register a parameterized test or suite, and they are not interchangeable: .each spreads an array case into separate callback parameters, while .for passes the case through untouched and hands the callback the TestContext as a second argument. A file that uses both makes every parameterized block a small puzzle about which shape its callback receives. This rule picks one form per registration name and reports the other.

test, it, and describe are configured independently, and a name that is not configured is not checked. That means the rule does nothing at all until at least one preference is set — enabling it without options is not an error, it simply never reports.

Both call forms are covered: a case array, as in test.each([1, 2]), and a tagged template table, as in test.each`a | b`. Modifiers written between the registration and the accessor — .skip, .only, .concurrent, .skipIf(…), .extend({…}) — do not hide it. The registration is resolved rather than name-matched, so an import from @rstest/core or @rstest/playwright, a global, and a local alias are all recognised, while a same-named import from another test framework and a local variable that merely shares the name are left alone. A suite registered as test.describe is governed by the describe preference. The diagnostic points at the .each or .for accessor, or, when a variable holds the already-parameterized registration, at that variable.

No fix is offered. Whether switching forms requires rewriting the callback depends on the shape of the cases, which is a runtime value the rule cannot inspect: [[1, 2]] reaches an .each callback as (a, b) and a .for callback as ([a, b]), while a list of scalars or a template table reaches both the same way.

#Incorrect

// { "test": "for" }
test.each([
  [2, 4],
  [3, 9],
])('squares %i', (input, expected) => {
  expect(square(input)).toBe(expected);
});

#Correct

// { "test": "for" }
test.for([
  [2, 4],
  [3, 9],
])('squares %i', ([input, expected]) => {
  expect(square(input)).toBe(expected);
});

#Options

{
  "rstest/consistent-each-for": [
    "error",
    {
      "test": "for",
      "describe": "each"
    }
  ]
}