WIP: use dynamic import to load es module tests.

bin/_mocha → bin/_mocha.js

@@ -171,6 +171,7 @@ program
   .option('-w, --watch', 'watch files for changes')
   .option('--check-leaks', 'check for global variable leaks')
   .option('--full-trace', 'display the full stack trace')
+  .option('--es-modules', 'load all test files as ECMAScript Modules')
   .option('--compilers <ext>:<module>,...', 'use the given module(s) to compile files', list, [])
   .option('--debug-brk', "enable node's debugger breaking on the first line")
   .option('--globals <names>', 'allow the given comma-delimited global [names]', list, [])
@@ -399,6 +400,12 @@ if (program.fullTrace) {
   mocha.fullTrace();
 }
 
+// --es-modules
+
+if (program.esModules) {
+  mocha.esModules();
+}
+
 // --growl
 
 if (program.growl) {

bin/mocha

@@ -10,7 +10,7 @@
 const spawn = require('child_process').spawn;
 const path = require('path');
 const getOptions = require('./options');
-const args = [path.join(__dirname, '_mocha')];
+const args = [path.join(__dirname, '_mocha.js')];
 
 // Load mocha.opts into process.argv
 // Must be loaded here to handle node-specific options
@@ -38,6 +38,7 @@ process.argv.slice(2).forEach(arg => {
       break;
     case '--gc-global':
     case '--es_staging':
+    case '--experimental-modules':
     case '--no-deprecation':
     case '--no-warnings':
     case '--prof':

lib/mocha.js

@@ -234,6 +234,34 @@ Mocha.prototype.loadFiles = function (fn) {
   fn && fn();
 };
 
+/**
+ * Load registered files via es6 dynamic imports.
+ *
+ * Note: `eval` is used in this function or else mocha will not
+ * compile on older node versions.
+ *
+ * @api private
+ */
+Mocha.prototype.dynamicallyImportFiles = function (fn) {
+  var self = this;
+  var suite = this.suite;
+  Promise
+    .all(this.files.map(function (file) {
+      file = path.resolve(file);
+      suite.emit('pre-require', global, file, self);
+      return eval('import(file)')
+        .then(function (module) {
+          suite.emit('require', module, file, self);
+          suite.emit('post-require', global, file, self);
+          return module;
+        });
+    }))
+    .then(function() {
+      fn();
+    })
+    .catch(fn);
+};
+
 /**
  * Enable growl support.
  *
@@ -334,6 +362,17 @@ Mocha.prototype.fullTrace = function () {
   return this;
 };
 
+/**
+ * Use dynamic imports to load tests as es modules.
+ *
+ * @return {Mocha}
+ * @api public
+ */
+Mocha.prototype.esModules = function () {
+  this.options.esModules = true;
+  return this;
+};
+
 /**
  * Enable growl support.
  *
@@ -532,9 +571,6 @@ Mocha.prototype.forbidPending = function () {
  * @return {Runner}
  */
 Mocha.prototype.run = function (fn) {
-  if (this.files.length) {
-    this.loadFiles();
-  }
   var suite = this.suite;
   var options = this.options;
   options.files = this.files;
@@ -569,5 +605,23 @@ Mocha.prototype.run = function (fn) {
     }
   }
 
-  return runner.run(done);
+  if (this.files.length) {
+    if (this.options.esModules) {
+      this.dynamicallyImportFiles(function (error) {
+        if (error) {
+          console.log(error);
+          done(1);
+        } else {
+          runner.run(done);
+        }
+      });
+    } else {
+      this.loadFiles();
+      runner.run(done);
+    }
+  } else {
+    runner.run(done);
+  }
+
+  return runner;
 };

test/integration/es-modules.spec.js

@@ -0,0 +1,55 @@
+'use strict';
+
+var run = require('./helpers').runMocha;
+var assert = require('assert');
+
+describe('esModules', function () {
+  describe('loading of es module tests', function () {
+    this.timeout(1000);
+    it('should load tests which use named exports', function (done) {
+      run('es-modules/named-export.fixture.mjs', ['--es-modules', '--experimental-modules', '--harmony-dynamic-import'], function (err, res) {
+        if (err) {
+          done(err);
+          return;
+        }
+        assert.equal(res.pending, 0);
+        assert.equal(res.passing, 1);
+        assert.equal(res.failing, 0);
+        assert.equal(res.code, 0);
+        done();
+      });
+    });
+
+    it('should load tests which use default exports', function (done) {
+      this.timeout(1000);
+      run('es-modules/default-export.fixture.mjs', ['--es-modules', '--experimental-modules', '--harmony-dynamic-import'], function (err, res) {
+        if (err) {
+          done(err);
+          return;
+        }
+        assert.equal(res.pending, 0);
+        assert.equal(res.passing, 1);
+        assert.equal(res.failing, 0);
+        assert.equal(res.code, 0);
+        done();
+      });
+    });
+  });
+
+  describe('loading of cjs tests when running with --experimental-modules and --dynamic-import', function () {
+    it('should load cjs test', function (done) {
+      this.timeout(1000);
+      run('es-modules/cjs-test.fixture.js', ['--es-modules', '--experimental-modules', '--harmony-dynamic-import'], function (err, res) {
+        if (err) {
+          done(err);
+          return;
+        }
+        assert.equal(res.pending, 0);
+        assert.equal(res.passing, 1);
+        assert.equal(res.failing, 0);
+        assert.equal(res.code, 0);
+        done();
+      });
+    });
+  });
+});

test/integration/fixtures/es-modules/cjs-module.js

@@ -0,0 +1,3 @@
+'use strict';
+
+exports.cjs = 'cjs';

test/integration/fixtures/es-modules/cjs-test.fixture.js

@@ -0,0 +1,8 @@
+var cjs = require('./cjs-module').cjs;
+
+
+describe('testing common js require', function () {
+  it('should be able to require cjs modules', function () {
+    assert(cjs, 'cjs');
+  });
+});

test/integration/fixtures/es-modules/default-export.fixture.mjs

@@ -0,0 +1,7 @@
+import double from './module.mjs'
+
+describe('testing imported function', function () {
+  it('imported value should double its argument', function () {
+    assert(double(5), 10);
+  });
+});

test/integration/fixtures/es-modules/module.mjs

@@ -0,0 +1,3 @@
+export const double = x => 2*x;
+
+export default double;

test/integration/fixtures/es-modules/named-export.fixture.mjs

@@ -0,0 +1,7 @@
+import { double } from './module.mjs'
+
+describe('testing imported function', function () {
+  it('imported value should double its argument', function () {
+    assert(double(5), 10);
+  });
+});

test/unit/mocha.spec.js

@@ -106,6 +106,19 @@ describe('Mocha', function () {
     });
   });
 
+  describe('.es-modules()', function () {
+    it('should set the es-modules option to true', function () {
+      var mocha = new Mocha(blankOpts);
+      mocha.esModules();
+      expect(mocha.options.esModules).to.equal(true);
+    });
+
+    it('should be chainable', function () {
+      var mocha = new Mocha(blankOpts);
+      expect(mocha.esModules()).to.equal(mocha);
+    });
+  });
+
   describe('.growl()', function () {
     it('should set the growl option to true', function () {
       var mocha = new Mocha(blankOpts);