deno/tests/unit_node/module_test.ts

// Copyright 2018-2025 the Deno authors. MIT license.

import {
  builtinModules,
  createRequire,
  findSourceMap,
  isBuiltin,
  Module,
  // @ts-ignore Our internal @types/node is at v18.16.19 which predates
  // this change. Updating it is difficult due to different types in Node
  // for `import.meta.filename` and `import.meta.dirname` that Deno
  // provides.
  register,
} from "node:module";
import { assert, assertEquals } from "@std/assert";
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 as Error).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);
});

Deno.test("[node/module isBuiltin] recognizes node builtins", () => {
  assert(isBuiltin("node:fs"));
  assert(isBuiltin("node:test"));
  assert(isBuiltin("fs"));
  assert(isBuiltin("buffer"));

  assert(!isBuiltin("internal/errors"));
  assert(!isBuiltin("test"));
  assert(!isBuiltin(""));
  // deno-lint-ignore no-explicit-any
  assert(!isBuiltin(undefined as any));
});

// https://github.com/denoland/deno/issues/22731
Deno.test("[node/module builtinModules] has 'module' in builtins", () => {
  assert(builtinModules.includes("module"));
});

// https://github.com/denoland/deno/issues/18666
Deno.test("[node/module findSourceMap] is a function", () => {
  assertEquals(findSourceMap("foo"), undefined);
});

// https://github.com/denoland/deno/issues/24902
Deno.test("[node/module register] is a function", () => {
  assertEquals(register("foo"), undefined);
});

Deno.test("[node/module] overriding Module._compile is possible and Node globals work", () => {
  // @ts-ignore Not documented but available
  const originalCompile = Module.prototype._compile;

  // @ts-ignore Not documented but available
  Module.prototype._compile = function (content: string, filename: string) {
    // deno-lint-ignore no-this-alias
    const mod = this;
    function require(id: string) {
      return mod.require(id);
    }
    require.resolve = function (request: string) {
      // @ts-ignore Not documented but available
      return Module._resolveFilename(request, mod);
    };
    require.main = process.mainModule;

    // Enable support to add extra extension types
    // @ts-ignore Not documented but available
    require.extensions = Module._extensions;
    // @ts-ignore Not documented but available
    require.cache = Module._cache;

    const dirname = path.dirname(filename);

    const wrapper = Module.wrap(content);
    // @ts-ignore can't index by a symbol
    const [f, err] = Deno[Deno.internal].core.evalContext(
      wrapper,
      `file:///${filename}`,
      [true],
    );
    assertEquals(err, null);
    const args = [
      mod.exports,
      require,
      mod,
      filename,
      dirname,
      process,
    ];
    f.apply(mod.exports, args);
    return mod;
  };

  const src = `module.exports = {
  clearImmediate: typeof clearImmediate,
  clearTimeout: typeof clearTimeout, 
  setImmediate: typeof setImmediate, 
  global: typeof global
};`;
  // @ts-ignore Not documented but available
  const ret = Module.prototype._compile(src, "file.js");
  const exports = ret.exports;
  assertEquals(exports.clearImmediate, "function");
  assertEquals(exports.clearTimeout, "function");
  assertEquals(exports.setImmediate, "function");
  assertEquals(exports.global, "object");
  // @ts-ignore Not documented but available
  Module.prototype._compile = originalCompile;
});