test-esm-loader-hooks.mjs

// Flags: --expose-internals
import '../common/index.mjs';
import mod from 'internal/modules/esm/loader';
import assert from 'assert';

const { ESMLoader } = mod;

{
  const esmLoader = new ESMLoader();

  const originalSpecifier = 'foo/bar';
  const importAssertions = { type: 'json' };
  const parentURL = 'file:///entrypoint.js';
  const resolvedURL = 'file:///foo/bar.js';
  const suggestedFormat = 'test';

  const customLoader1 = {
    resolve(specifier, context, defaultResolve) {
      assert.strictEqual(specifier, originalSpecifier);
      assert.deepStrictEqual(Object.keys(context), [
        'conditions',
        'importAssertions',
        'parentURL',
      ]);
      assert.ok(Array.isArray(context.conditions));
      assert.strictEqual(context.importAssertions, importAssertions);
      assert.strictEqual(context.parentURL, parentURL);
      assert.strictEqual(typeof defaultResolve, 'function');

      // This doesn't matter. just to avoid errors
      return {
        format: suggestedFormat,
        url: resolvedURL,
      };
    },
    load(resolvedURL, context, defaultLoad) {
      assert.strictEqual(resolvedURL, resolvedURL);
      assert.ok(new URL(resolvedURL));
      assert.deepStrictEqual(Object.keys(context), [
        'format',
        'importAssertions',
      ]);
      assert.strictEqual(context.format, suggestedFormat);
      assert.strictEqual(context.importAssertions, importAssertions);
      assert.strictEqual(typeof defaultLoad, 'function');

      // This doesn't matter. just to avoid errors
      return {
        format: 'module',
        source: '',
      };
    },
  };

  esmLoader.addCustomLoaders(customLoader1);

  esmLoader.resolve(
    originalSpecifier,
    parentURL,
    importAssertions,
  );
  esmLoader.load(
    resolvedURL,
    {
      format: suggestedFormat,
      importAssertions,
    },
    function mockDefaultLoad() {},
  );
}