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Lightweight runner for ECMAScript Temporal's Test262 tests

This package provides a fast way for polyfills of ECMAScript Temporal to run Temporal's 6,300+ Test262 tests. Test262 (https://github.com/tc39/test262) is the official conformance test suite for ECMAScript, and this package quickly runs a subset of those tests that are specific to Temporal. All Temporal polyfills should pass Test262.

This runner is much faster than test262-harness (the default Test262 harness) because:

  • It runs only 6,300+ Temporal-specific tests, instead of the full suite.
  • It pre-parses the Temporal polyfill into a vm.Script, instead of reading and parsing the whole file once for each test like the prelude option of test262-harness does. This causes tests to run at least 10x faster.

A typical run of all 6300+ Temporal tests will finish in less than 30 seconds.

For code coverage, set the environment variable NODE_V8_COVERAGE to the path (relative to the working directory) where coverage metrics should be output. These can be processed with the c8 tool. NOTE: as of Node 18.7 there is a memory leak that makes it impossible to run the entire suite with NODE_V8_COVERAGE, so for code coverage tests you should run it in chunks.

Example Usage

import runTest262 from 'temporal-test262-runner';

const result = runTest262({
  test262Dir: 'test262',
  polyfillCodeFile: 'dist/script.js',
  expectedFailureFiles: ['test/expected-failures.txt'],
  testGlobs: process.argv.slice(2)
});

// if result is `true`, all tests succeeded
process.exit(result ? 0 : 1);

Options

  • polyfillCodeFile: string - Filename of the Temporal polyfill. Must be a single ECMAScript file that contains the Temporal object injected into the global namespace, as well as Temporal-related changes polyfilled into Intl and Date built-in objects.
  • test262Dir: string - Root directory of the test262 submodule repo.
  • testGlobs?: string[] - If omitted, all Temporal tests will be run. This option provides glob patterns that specify a subset of tests to be run. Globs are resolved relative to test/**/Temporal/ subdirectories of test262Dir. If a pattern doesn't match any files relative to test/**/Temporal/, it will also try to match relative to the current working directory, so that tab completion works. Example: [ 'PlainDateTime/**', 'prototype/with/*.js' ]
  • expectedFailureFiles?: string[] - Optional array of text filenames that each contain a list of test files (relative to the test subdirectory of test262Dir) that are expected to fail. Lines starting with # and blank lines are ignored. Lines from multiple files will be concatenated and de-duped. Example: 
    # https://github.com/tc39/test262/pull/3548
built-ins/Temporal/Duration/compare/argument-string-negative-fractional-units.js
built-ins/Temporal/Duration/from/argument-string-negative-fractional-units.js
  • updateExpectedFailureFiles?: boolean - Used in local development to automatically revise expected-failure files after making code changes that fix test failures, removing tests that were expected to fail but now pass from the expected-failure files. This option does not add newly failing tests to the expected-failure files - this must be done manually. We recommend this option be set using an optional CLI flag for ease of use.
  • timeoutMsecs?: number|string - Optional number of milliseconds to allow tests to run before they'll be terminated. This ensures that infinite-loop (or super-long) tests won't prevent others from completing. Default is 2000 msecs (2 seconds) which should be fine even for slow CI systems. But when running tests in a debugger, set the timeout to much longer (like 1 hour) so that you'll have time to debug tests. If a string is provided, it'll be parsed into a number before evaluation, which makes it easier for callers to pass environment variables as-is. NaN values will silently be assigned the default value.