Tests: splitAsync use import()

lib/serialize/createModule.js

@@ -7,11 +7,8 @@
 
 // Exports
 
-// Use implementation which uses `import()` if possible, otherwise use fallback.
-// Does not work correctly in Jest - there are separate Mocha tests to cover this.
-module.exports = process.env.NODE_ENV !== 'test' ? createModulePromise : createModulePromiseFallback;
+module.exports = createModulePromise;
 
-// Implementation using `import()`
 let importCounter = 0;
 
 /**
@@ -37,38 +34,3 @@ function createModulePromise(val, splitPoint) {
 
 	return promise;
 }
-
-/**
- * Fallback module object creator which does not use `import()`.
- *
- * The module object it creates resembles a native module namespace object in every respect except:
- * 1. `require('util').types.isModuleNamespaceObject(moduleObj)` returns `false`
- * 2. `moduleObj.default = x` does not throw an error
- * 3. `console.log(moduleObj)` output is slightly different
- *
- * @param {*} val - Value to create module from
- * @param {Object} splitPoint - Split point object
- * @returns {Promise} - Promise which resolves to module object
- */
-function createModulePromiseFallback(val, splitPoint) {
-	const moduleObj = Object.seal(
-		Object.create(null, {
-			default: {
-				value: val,
-				writable: true,
-				enumerable: true,
-				configurable: false
-			},
-			[Symbol.toStringTag]: {
-				value: 'Module',
-				writable: false,
-				enumerable: false,
-				configurable: false
-			}
-		})
-	);
-
-	splitPoint.moduleObj = moduleObj;
-
-	return Promise.resolve(moduleObj);
-}