1 files changed, 72 insertions, 0 deletions
diff --git a/tests/unit_node/module_test.ts b/tests/unit_node/module_test.ts
new file mode 100644
index 000000000..f8e117254
--- /dev/null
+++ b/tests/unit_node/module_test.ts
@@ -0,0 +1,72 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+import { createRequire, Module } from "node:module";
+import { assert, assertEquals } from "@test_util/std/assert/mod.ts";
+import process from "node:process";
+import * as path from "node:path";
+
+Deno.test("[node/module _preloadModules] has internal require hook", () => {
+  // Check if it's there
+  // deno-lint-ignore no-explicit-any
+  (Module as any)._preloadModules([
+    "./tests/unit_node/testdata/add_global_property.js",
+  ]);
+  // deno-lint-ignore no-explicit-any
+  assertEquals((globalThis as any).foo, "Hello");
+});
+
+Deno.test("[node/module runMain] loads module using the current process.argv", () => {
+  process.argv = [
+    process.argv[0],
+    "./tests/unit_node/testdata/add_global_property_run_main.js",
+  ];
+
+  // deno-lint-ignore no-explicit-any
+  (Module as any).runMain();
+  // deno-lint-ignore no-explicit-any
+  assertEquals((globalThis as any).calledViaRunMain, true);
+});
+
+Deno.test("[node/module _nodeModulePaths] prevents duplicate /node_modules/node_modules suffix", () => {
+  // deno-lint-ignore no-explicit-any
+  const actual: string[] = (Module as any)._nodeModulePaths(
+    path.join(process.cwd(), "testdata", "node_modules", "foo"),
+  );
+
+  assert(
+    !actual.some((dir) => /node_modules[/\\]node_modules/g.test(dir)),
+    "Duplicate 'node_modules/node_modules' suffix found",
+  );
+});
+
+Deno.test("[node/module _nodeModulePaths] prevents duplicate root /node_modules", () => {
+  // deno-lint-ignore no-explicit-any
+  const actual: string[] = (Module as any)._nodeModulePaths(
+    path.join(process.cwd(), "testdata", "node_modules", "foo"),
+  );
+
+  assert(
+    new Set(actual).size === actual.length,
+    "Duplicate path entries found",
+  );
+  const root = path.parse(actual[0]).root;
+  assert(
+    actual.includes(path.join(root, "node_modules")),
+    "Missing root 'node_modules' directory",
+  );
+});
+
+Deno.test("Built-in Node modules have `node:` prefix", () => {
+  let thrown = false;
+  try {
+    // @ts-ignore We want to explicitly test wrong call signature
+    createRequire();
+  } catch (e) {
+    thrown = true;
+    const stackLines = e.stack.split("\n");
+    // Assert that built-in node modules have `node:<mod_name>` specifiers.
+    assert(stackLines.some((line: string) => line.includes("(node:module:")));
+  }
+
+  assert(thrown);
+});