Pass file name to change event.

index.js

@@ -37,7 +37,7 @@ exports.create = function () {
 
   Store.prototype.add = function (file) {
     store[file.path] = file;
-    this.emit('change');
+    this.emit('change', file.path);
     return this;
   };
 

test/index.js

@@ -61,13 +61,23 @@ describe('mem-fs', function () {
       assert.equal(this.store.add(coffeeFile), this.store);
     });
 
-    it('triggers change event', function (done) {
-      this.store.on('change', function () {
-        var file = this.store.get('/test/file.coffee');
-        assert.equal(file.contents.toString(), 'test = 123');
-        done();
-      }.bind(this));
-      this.store.add(coffeeFile);
+    describe('change event', () => {
+      it('is triggered', function (done) {
+        this.store.on('change', function () {
+          var file = this.store.get('/test/file.coffee');
+          assert.equal(file.contents.toString(), 'test = 123');
+          done();
+        }.bind(this));
+        this.store.add(coffeeFile);
+      });
+
+      it('passes the file name to the listener', function (done) {
+        this.store.on('change', eventFile => {
+          assert.equal(eventFile, coffeeFile.path);
+          done();
+        });
+        this.store.add(coffeeFile);
+      });
     });
   });