Fix for ES Module detection using npm@7 (#4295)

lib/migrations/util/import-file.js

@@ -1,14 +1,13 @@
-// When run via npm, we can leverage the injected environment variables to infer the import type
-const isTypeModule = process.env.npm_package_type === 'module';
+const isModuleType = require('./is-module-type');
 
 /**
  * imports 'mjs', else requires.
  * NOTE: require me late!
  * @param {string} filepath
  * @todo WARN on version 10 and '--experimental-modules' and '--esm'
  */
-module.exports = function importFile(filepath) {
-  return isTypeModule || filepath.endsWith('.mjs')
+module.exports = async function importFile(filepath) {
+  return (await isModuleType(filepath))
     ? import(require('url').pathToFileURL(filepath))
     : require(filepath);
 };

lib/migrations/util/is-module-type.js

@@ -0,0 +1,16 @@
+const { readFile } = require('./fs');
+
+module.exports = async function isModuleType(filepath) {
+    try {
+        if (process.env.npm_package_json) {
+            // npm >= 7.0.0
+            const packageJson = JSON.parse(await readFile(process.env.npm_package_json, 'utf-8'));
+            if (packageJson.type === 'module') {
+                return true;
+            }
+        }
+    } catch (e) {
+        console.warn('Error reading package.json', e);
+    }
+    return process.env.npm_package_type === 'module' || filepath.endsWith('.mjs')
+}

test/db-less-test-suite.js

@@ -6,6 +6,7 @@ describe('Util Tests', function () {
   // Unit Tests for utilities.
   require('./unit/query/string');
   require('./unit/migrations/util/fs');
+  require('./unit/migrations/util/is-module-type');
   require('./unit/util/nanoid');
   require('./unit/util/save-async-stack');
   require('./unit/util/comma-no-paren-regex');

test/unit/migrations/util/is-module-type.js

@@ -0,0 +1,60 @@
+
+const path = require('path');
+
+const { expect } = require('chai');
+const isModuleType = require('../../../../lib/migrations/util/is-module-type.js');
+require('../../../util/chai-setup');
+
+describe('isModuleType', () => {
+  let originalPackgeType;
+  let originalPackageJson;
+
+  before(()=>{
+    originalPackgeType = process.env.npm_package_type;
+    originalPackageJson = process.env.npm_package_json;
+  });
+
+  after(() => {
+     process.env.npm_package_type = originalPackgeType;
+     process.env.npm_package_json = originalPackageJson;
+  })
+
+  beforeEach(()=>{
+    delete process.env.npm_package_type;
+    delete process.env.npm_package_json;
+  });
+
+  it('should return true if the file is a .mjs file', async () => {
+    expect(await isModuleType('test.mjs')).to.be.true;
+  });
+
+  it('should return true if type=module with npm < 7.0.0', async () => {
+    process.env.npm_package_type = 'module';
+    expect(await isModuleType('test.js')).to.be.true;
+  });
+
+  it('should return false if type=commonjs with npm < 7.0.0', async () => {
+    process.env.npm_package_type = 'commonjs';
+    expect(await isModuleType('test.js')).to.be.false;
+  });
+
+  it('should return true if type=module with npm >= 7.0.0', async () => {
+    process.env.npm_package_json = path.normalize(__dirname + '/test/package-module.json');
+    expect(await isModuleType('test.js')).to.be.true;
+  });
+
+  it('should return false if type=commonjs with npm >= 7.0.0', async () => {
+    process.env.npm_package_json = path.normalize(__dirname + '/test/package-commonjs.json');
+    expect(await isModuleType('test.js')).to.be.false;
+  });
+
+  it('should return false if package.json is invalid and file type is js with npm >= 7.0.0', async () => {
+    process.env.npm_package_json = path.normalize(__dirname + '/test/package-invalid.json');
+    expect(await isModuleType('test.js')).to.be.false;
+  });
+
+  it('should return true if package.json is invalid and file type is mjs with npm >= 7.0.0', async () => {
+    process.env.npm_package_json = path.normalize(__dirname + '/test/package-invalid.json');
+    expect(await isModuleType('test.mjs')).to.be.true;
+  });
+})

test/unit/migrations/util/test/package-commonjs.json

@@ -0,0 +1,3 @@
+{
+    "type": "commonjs"
+}

test/unit/migrations/util/test/package-invalid.json

@@ -0,0 +1,4 @@
+// Intentionally invalid JSON
+{
+    "type": ,
+}

test/unit/migrations/util/test/package-module.json

@@ -0,0 +1,3 @@
+{
+    "type": "module"
+}