Try to get tests to run on Windows

index.js

@@ -90,7 +90,7 @@ function requireString(code, dirname, options) {
  */
 function resolveIfNeeded(dirname, specifier) {
   if (specifier.startsWith(".")) {
-    specifier = path.resolve(dirname, specifier);
+    specifier = new URL(specifier, dirname).toString();
   }
   return specifier;
 }
@@ -113,20 +113,27 @@ async function importString(code, dirname, options) {
     throw new Error("Requires node.js 20.8+ or 21.");
   }
 
+  const fileUrl = options.filename.startsWith("file:")
+    ? options.filename
+    : url.pathToFileURL(options.filename).toString();
+  const dirUrl = dirname.startsWith("file:")
+    ? dirname
+    : url.pathToFileURL(dirname).toString() + "/";
+
   const mod = new vm.SourceTextModule(code, {
-    identifier: options.filename,
+    identifier: fileUrl,
     context: vm.createContext(options.context),
     initializeImportMeta(meta) {
-      meta.url = String(url.pathToFileURL(options.filename));
+      meta.url = fileUrl;
     },
     // @ts-expect-error Types in @types/node are wrong.
     importModuleDynamically(specifier) {
-      return import(resolveIfNeeded(dirname, specifier));
+      return import(resolveIfNeeded(dirUrl, specifier));
     },
   });
 
   await mod.link(async(specifier, referencingModule) => {
-    const resolvedSpecifier = resolveIfNeeded(dirname, specifier);
+    const resolvedSpecifier = resolveIfNeeded(dirUrl, specifier);
     const targetModule = await import(resolvedSpecifier);
     const exports = Object.keys(targetModule);
 

package.json

@@ -6,7 +6,7 @@
   "scripts": {
     "build": "tsc",
     "lint": "eslint .",
-    "test": "c8 node --experimental-vm-modules --test"
+    "test": "c8 node --stack-trace-limit=1000 --experimental-vm-modules --test"
   },
   "keywords": [
     "vm",

test/index.test.js

@@ -1,9 +1,9 @@
 "use strict";
 
 const assert = require("node:assert");
-const test = require("node:test");
 const fromMem = require("../index.js");
-const { pathToFileURL } = require("url");
+const { join } = require("node:path");
+const test = require("node:test");
 
 test("options", async() => {
   assert.equal(typeof fromMem, "function");
@@ -20,7 +20,7 @@ test("commonjs", async() => {
   });
   assert.equal(cjs, 4);
   await assert.rejects(() => fromMem("throw new Error('foo')", {
-    filename: `${__dirname}/test2.js`,
+    filename: join(__dirname, "test2.js"),
     format: "bare",
   }), (/** @type {Error} */ err) => {
     assert(/test2\.js/.test(err.stack), err.stack);
@@ -30,30 +30,30 @@ test("commonjs", async() => {
 
 test("esm", async() => {
   const mjs4 = await fromMem("export default 5", {
-    filename: `${__dirname}/test4.mjs`,
+    filename: join(__dirname, "test4.js"),
     format: "es",
   });
   assert.equal(mjs4.default, 5);
 
   const mjs5 = await fromMem(`
 import {foo} from './fixtures/example.mjs';
 export default foo();`, {
-    filename: `${__dirname}/test5.mjs`,
+    filename: join(__dirname, "test5.js"),
     format: "es",
   });
   assert.equal(mjs5.default, 6);
 
   const mjs6 = await fromMem(`
 export default import.meta.url`, {
-    filename: `${__dirname}/test6.mjs`,
+    filename: join(__dirname, "test6.js"),
     format: "es",
   });
-  assert.equal(mjs6.default, pathToFileURL(`${__dirname}/test6.mjs`));
+  assert.match(mjs6.default, /test6\.js$/);
 
   const mjs7 = await fromMem(`
 const {foo} = await import('./fixtures/example.mjs');
 export default foo();`, {
-    filename: `${__dirname}/test5.mjs`,
+    filename: join(__dirname, "test7.js"),
     format: "es",
   });
   assert.equal(mjs7.default, 6);