New: Support .mjs extension (closes #65)

README.md

@@ -148,6 +148,7 @@ Map file types to modules which provide a [require.extensions] loader.
   '.litcoffee': ['coffeescript/register', 'coffee-script/register', 'coffeescript', 'coffee-script'],
   '.liticed': 'iced-coffee-script/register',
   '.ls': ['livescript', 'LiveScript'],
+  '.mjs': '/absolute/path/to/interpret/mjs-stub.js',
   '.node': null,
   '.toml': {
     module: 'toml-require',

index.js

@@ -2,6 +2,8 @@ var path = require('path');
 
 var endsInBabelJs = /\.babel\.[jt]s(x)$/;
 
+var mjsStub = path.join(__dirname, 'mjs-stub');
+
 function ignoreNonBabelAndNodeModules(file) {
   return !endsInBabelJs.test(file) &&
     path.relative(process.cwd(), file).split(path.sep).indexOf('node_modules') >= 0;
@@ -130,6 +132,7 @@ var extensions = {
   '.litcoffee': ['coffeescript/register', 'coffee-script/register', 'coffeescript', 'coffee-script'],
   '.liticed': 'iced-coffee-script/register',
   '.ls': ['livescript', 'LiveScript'],
+  '.mjs': mjsStub,
   '.node': null,
   '.toml': {
     module: 'toml-require',
@@ -193,6 +196,7 @@ var jsVariantExtensions = [
   '.litcoffee',
   '.liticed',
   '.ls',
+  '.mjs',
   '.ts',
   '.tsx',
   '.wisp',

mjs-stub.js

@@ -0,0 +1 @@
+require.extensions['.mjs'] = null;

package.json

@@ -15,7 +15,8 @@
   "main": "index.js",
   "files": [
     "LICENSE",
-    "index.js"
+    "index.js",
+    "mjs-stub.js"
   ],
   "scripts": {
     "lint": "eslint .",

test/fixtures/mjs/0/package.json

@@ -0,0 +1 @@
+{}

test/fixtures/mjs/0/test.mjs

@@ -0,0 +1,9 @@
+export default {
+  data: {
+    trueKey: true,
+    falseKey: false,
+    subKey: {
+      subProp: 1
+    }
+  }
+};

test/fixtures/mjs/1/package.json

@@ -0,0 +1 @@
+{}

test/fixtures/mjs/1/test.mjs

@@ -0,0 +1,9 @@
+module.exports = {
+  data: {
+    trueKey: true,
+    falseKey: false,
+    subKey: {
+      subProp: 1
+    }
+  }
+};

test/index.js

@@ -84,6 +84,11 @@ describe('interpret.extensions', function() {
       return attempts;
     }
 
+    // We will handle the .mjs tests separately
+    if (ext === '.mjs') {
+      return attempts;
+    }
+
     modules.forEach(function(mod, idx) {
       if (mod && typeof mod !== 'string') {
         mod = mod.module;
@@ -220,9 +225,71 @@ describe('interpret.extensions', function() {
           };
           expect(require(fixture)).toEqual(expected);
       }
-
       done();
     });
   });
 
+  it('does not error with the .mjs extension', function(done) {
+    var ext = '.mjs';
+    var fixture = './fixtures/' + ext.slice(1) + '/0/test' + ext;
+
+    var result = rechoir.prepare(extensions, fixture);
+
+    expect(Array.isArray(result)).toEqual(true);
+    expect(result[0].moduleName).toEqual(path.join(__dirname, '../mjs-stub'));
+    done();
+  });
+
+  it('the module can be loaded with import(), ignoring the loader', function() {
+    if (nodeVersion.major < 12) {
+      this.skip();
+    }
+
+    var ext = '.mjs';
+    var fixture = './fixtures/' + ext.slice(1) + '/0/test' + ext;
+
+    rechoir.prepare(extensions, fixture);
+
+    var expected = {
+      data: {
+        trueKey: true,
+        falseKey: false,
+        subKey: {
+          subProp: 1,
+        },
+      },
+    };
+
+    // This avoid SyntaxError when parsing on old node versions
+    var imprt = new Function('a', 'return import(a)');
+
+    return imprt(fixture)
+      .then(function(result) {
+        expect(result.default).toEqual(expected);
+      });
+  });
+
+  it('stubs .mjs extension with null on old node that do not care about it', function(done) {
+    if (nodeVersion.major > 10) {
+      this.skip();
+    }
+
+    var ext = '.mjs';
+    var fixture = './fixtures/' + ext.slice(1) + '/1/test' + ext;
+
+    rechoir.prepare(extensions, fixture);
+
+    var expected = {
+      data: {
+        trueKey: true,
+        falseKey: false,
+        subKey: {
+          subProp: 1,
+        },
+      },
+    };
+    expect(require(fixture)).toEqual(expected);
+    done();
+  });
+
 });