test: add a simple test for import defer of a CJS module

[MayaLekova]

test: add a simple test for import defer of a CJS module

This tests imports a CommonJS modules with the defer modifier.
It ensures that the imported module is not evaluated before
accessing properties form its exports.

[MayaLekova]

@nicolo-ribaudo and @joyeecheung please take a look, thanks!

[joyeecheung]

Suggested change

	assert.equal(imported.default.foo, 42);
	assert.equal(imported.default.identifier, 'package-type-commonjs');
	assert.equal(imported.foo, 42);
	assert.deepStrictEqual(['defer-1'], globalThis.eval_list);
	assert.equal(imported.identifier, 'package-type-commonjs');

The lexer should recognize these. Also we should test that it only gets evaluated once.

[joyeecheung]

Suggested change

	assert.partialDeepStrictEqual(['defer-1'], globalThis.eval_list);
	assert.deepStrictEqual(['defer-1'], globalThis.eval_list);

It shouldn't be partial, if there are anything else, it's a bug.

[joyeecheung]

Suggested change

	assert.strictEqual(globalThis.eval_list.length, 0);
	assert.deepStrictEqual(globalThis.eval_list, []);

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.13%. Comparing base (4bec191) to head (2d51c34).
⚠️ Report is 22 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #64694   +/-   ##
=======================================
  Coverage   90.13%   90.13%           
=======================================
  Files         741      741           
  Lines      242106   242112    +6     
  Branches    45551    45595   +44     
=======================================
+ Hits       218211   218221   +10     
+ Misses      15430    15365   -65     
- Partials     8465     8526   +61     

see 50 files with indirect coverage changes

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[jasnell]

tiniest optional nit...

globalThis.eval_list ??= ['defer-1'];

[nicolo-ribaudo]

It would be better to swap these two statements, so that when reading somebody does not mistakenly assume that globalThis.eval_list = [] would be evaluated first (imports are hoisted and executed before code in the file).

This test right now would pass regardless of whether import defer is eager or deferred. If it's eager it passes because:

• after the eager ../fixtures/es-modules/module-cjs-deferred-eval.js evaluation, this file sets globalThis.eval_list = [];. Then it asserts that its length is 0, which is obviously true because we just set it to an empty array.
• further down, in assert.partialDeepStrictEqual(['defer-1'], globalThis.eval_list);, we are checking that ['defer-1'] contains all the elements of globalThis.eval_list. If globalThis.eval_list is empty, that's tautologically true.

I have not run this test, but I assume the reason in test/fixtures/es-modules/module-cjs-deferred-eval.js you had to add if (!globalThis.eval_list) { globalThis.eval_list = []; } is because the CJS module is indeed not being deferred, so it's running before that this file defines globalThis.eval_list = [].

Maybe better, either one of this:

• move the globalThis.eval_list = [] initialization to a separate file that is imported at the beginning of this one, before the other imports, so that we know it runs first
• use a boolean instead of an array, and then we don't need to pre-initialize it.