Restore older node support

tests/scenarios/core-resolver-test.ts

@@ -578,7 +578,7 @@ Scenarios.fromProject(() => new Project())
             'app.js': `import "rsvp"`,
           });
           await configure({});
-          expectAudit.module('./app.js').resolves('rsvp').to(resolve('/@embroider/external/rsvp').replaceAll(sep, '/'));
+          expectAudit.module('./app.js').resolves('rsvp').to(resolve('/@embroider/external/rsvp').split(sep).join('/'));
         });
 
         test(`known ember-source-provided virtual packages are not externalized when explicitly included in deps`, async function () {

tests/scenarios/shared-internals-test.ts

@@ -0,0 +1,53 @@
+import QUnit from 'qunit';
+import { Project, Scenarios } from 'scenario-tester';
+
+const { module: Qmodule, test } = QUnit;
+
+Scenarios.fromProject(() => new Project('shared-internals-tests'))
+  .map('shared-internals', project => {
+    project.pkg.volta = {
+      node: '12.22.1',
+    };
+    project.linkDependency('@embroider/shared-internals', { baseDir: __dirname });
+    project.linkDependency('qunit', { baseDir: __dirname });
+    project.linkDependency('semver', { baseDir: __dirname });
+
+    project.mergeFiles({
+      'test.js': `
+        const { module: QModule, test } = require("qunit");
+        const semver = require("semver");
+        const { PackageCache } = require("@embroider/shared-internals");
+
+        QModule("shared-internals", function () {
+          test("testing on node 12", function (assert) {
+            assert.ok(
+              semver.satisfies(process.version, "^12.0.0"),
+              \`\${process.version} should be what we expected\`
+            );
+          });
+
+          test("smoke test", async function (assert) {
+            let pk = PackageCache.shared("my-test", __dirname);
+            assert.equal(pk.get(__dirname).name, "shared-internals-tests");
+          });
+        });
+      `,
+    });
+  })
+  .forEachScenario(scenario => {
+    Qmodule(scenario.name, function () {
+      test('run tests', async function (assert) {
+        let app = await scenario.prepare();
+
+        // if we just try to invoke node directly in a child process, our own
+        // volta settings dominate over the test app's
+        let tryit = await app.execute('volta which node');
+        if (tryit.exitCode !== 0) {
+          throw new Error('unable to locate our node version');
+        }
+        let nodebin = tryit.output.trim();
+        let result = await app.execute(`${nodebin} ./node_modules/.bin/qunit ./test.js`);
+        assert.equal(result.exitCode, 0, result.output);
+      });
+    });
+  });

tsconfig.json

@@ -7,7 +7,7 @@
     "./tests/scenarios/**/*.ts"
   ],
   "compilerOptions": {
-    "target": "es2021",
+    "target": "es2019",
     "module": "commonjs",
     "declaration": true,
     "typeRoots": ["types", "node_modules/@types"],