test: add smoke tests for defer importing synthetic modules

test/es-module/test-defer-import-builtin-module.mjs

@@ -0,0 +1,29 @@
+// Flags: --js-defer-import-eval --expose-internals
+
+// Test that uses import.defer for a builtin module. Currently
+// defer importing of a synthetic module should be a no-op
+// in Node.js as they are born pre-evaluated, so the test
+// is mostly a smoke test that Node doesn't crash.
+
+// TODO: after deferring the evaluation of builtin modules
+// is implemented, accessing any property from it will
+// trigger the evaluation.
+
+import '../common/index.mjs';
+import * as assert from 'assert';
+
+// Check that there are no modules with 'http' in their name loaded yet.
+let modules = process.moduleLoadList.filter((item) => item.endsWith('http'));
+assert.strictEqual(modules.length, 0);
+
+const intermediate = await import('../fixtures/es-modules/import-builtin-module-intermediate.mjs');
+
+// Check that after dynamically importing the module with imports 'http'
+// itself, the builtin module is already present in the module list.
+modules = process.moduleLoadList.filter((item) => item.endsWith('http'));
+assert.partialDeepStrictEqual(modules, ['NativeModule http']);
+
+// Check that the imported module contains some known properties.
+assert.notStrictEqual(intermediate.http.STATUS_CODES, undefined);
+assert.notStrictEqual(intermediate.http.createServer, undefined);
+assert.strictEqual(typeof intermediate.http.createServer, 'function');

test/es-module/test-defer-import-json-module.mjs

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+// Flags: --js-defer-import-eval
+
+// Test that uses import.defer for a JSON module. Currently
+// defer importing of a synthetic module should be a no-op
+// in Node.js, so the test is mostly a smoke test that Node
+// doesn't crash.
+
+import '../common/index.mjs';
+import * as assert from 'assert';
+
+import defer * as imported_json
+  from '../fixtures/json-with-directory-name-module/module-stub.json'
+  with { type: 'json' };
+
+// eslint-disable-next-line no-duplicate-imports
+import * as imported_json_eager
+  from '../fixtures/json-with-directory-name-module/module-stub.json'
+  with { type: 'json' };
+
+// Check that the imported object has the expected key/value.
+assert.strictEqual(imported_json.default.rocko, 'artischocko');
+assert.deepStrictEqual(imported_json_eager.default, imported_json.default);

test/es-module/test-defer-import-text-module.mjs

@@ -0,0 +1,18 @@
+// Flags: --js-defer-import-eval --experimental-import-text
+
+// Test that uses import.defer for a text module. Currently
+// defer importing of a synthetic module should be a no-op
+// in Node.js, so the test is mostly a smoke test that Node
+// doesn't crash.
+
+import '../common/index.mjs';
+import * as assert from 'assert';
+
+import defer * as imported_text
+  from '../fixtures/file-to-read-without-bom.txt'
+  with { type: 'text' };
+
+const expected_text = 'abc\ndef\nghi\n';
+
+// Check that the imported text has the expected value.
+assert.strictEqual(imported_text.default, expected_text);

test/fixtures/es-modules/import-builtin-module-intermediate.mjs

@@ -0,0 +1,8 @@
+// This module uses import.defer to import the http builtin module.
+// It's dynamically imported by a test module, to ensure the HTTP
+// module is actually present in the module list after importing
+// this middle module.
+
+// Import the http builtin module and export all its properties.
+import defer * as http from 'node:http';
+export { http };