diff --git a/package.json b/package.json
index cd40956..37a4636 100644
--- a/package.json
+++ b/package.json
@@ -19,6 +19,7 @@
   },
   "devDependencies": {
     "babel-core": "^6.0.10",
+    "babel-preset-es2015": "^6.0.0",
     "mocha": "^2.2.4"
   },
   "directories": {
@@ -51,6 +52,6 @@
     "url": "http://github.com/power-assert-js/babel-plugin-espower.git"
   },
   "scripts": {
-    "test": "mocha"
+    "test": "mocha --timeout 7000"
   }
 }
diff --git a/test/fixtures/ArrayExpression/expected.js b/test/fixtures/ArrayExpression/expected.js
index f0a2a05..1573538 100644
--- a/test/fixtures/ArrayExpression/expected.js
+++ b/test/fixtures/ArrayExpression/expected.js
@@ -1,23 +1,23 @@
 'use strict';
 
 assert(assert._expr(assert._capt([assert._capt(foo, 'arguments/0/elements/0'), assert._capt(bar, 'arguments/0/elements/1')], 'arguments/0'), {
-  content: 'assert([foo,bar])',
+  content: 'assert([foo, bar])',
   filepath: 'test/fixtures/ArrayExpression/fixture.js',
   line: 3
 }));
 
 assert(assert._expr(assert._capt(assert._capt(typeof assert._capt([assert._capt([assert._capt(assert._capt(foo, 'arguments/0/left/argument/elements/0/elements/0/object').bar, 'arguments/0/left/argument/elements/0/elements/0'), assert._capt(baz(assert._capt(moo, 'arguments/0/left/argument/elements/0/elements/1/arguments/0')), 'arguments/0/left/argument/elements/0/elements/1')], 'arguments/0/left/argument/elements/0'), assert._capt(+assert._capt(fourStr, 'arguments/0/left/argument/elements/1/argument'), 'arguments/0/left/argument/elements/1')], 'arguments/0/left/argument'), 'arguments/0/left') === 'number', 'arguments/0'), {
-  content: 'assert(typeof [[foo.bar,baz(moo)],+fourStr] === \'number\')',
+  content: 'assert(typeof [[foo.bar, baz(moo)], +fourStr] === \'number\')',
   filepath: 'test/fixtures/ArrayExpression/fixture.js',
   line: 5
 }));
 
 assert.notDeepEqual(assert._expr(assert._capt([assert._capt(foo, 'arguments/0/elements/0'), assert._capt(bar, 'arguments/0/elements/1')], 'arguments/0'), {
-  content: 'assert.notDeepEqual([foo,bar], [hoge,fuga,piyo])',
+  content: 'assert.notDeepEqual([foo, bar], [hoge, fuga, piyo])',
   filepath: 'test/fixtures/ArrayExpression/fixture.js',
   line: 7
 }), assert._expr(assert._capt([assert._capt(hoge, 'arguments/1/elements/0'), assert._capt(fuga, 'arguments/1/elements/1'), assert._capt(piyo, 'arguments/1/elements/2')], 'arguments/1'), {
-  content: 'assert.notDeepEqual([foo,bar], [hoge,fuga,piyo])',
+  content: 'assert.notDeepEqual([foo, bar], [hoge, fuga, piyo])',
   filepath: 'test/fixtures/ArrayExpression/fixture.js',
   line: 7
 }));
diff --git a/test/fixtures/FunctionExpression/expected.js b/test/fixtures/FunctionExpression/expected.js
index 9facf34..92a3b79 100644
--- a/test/fixtures/FunctionExpression/expected.js
+++ b/test/fixtures/FunctionExpression/expected.js
@@ -7,7 +7,7 @@ assert(function (a, b) {
 assert(assert._expr(assert._capt(assert._capt(baz, 'arguments/0/left') === assert._capt((function (a, b) {
   return a + b;
 })(assert._capt(foo, 'arguments/0/right/arguments/0'), assert._capt(bar, 'arguments/0/right/arguments/1')), 'arguments/0/right'), 'arguments/0'), {
-  content: 'assert(baz === function (a, b) {return a + b;}(foo, bar))',
+  content: 'assert(baz === (function (a, b) { return a + b; })(foo, bar))',
   filepath: 'test/fixtures/FunctionExpression/fixture.js',
   line: 5
 }));
diff --git a/test/fixtures/babel6/expected.js b/test/fixtures/babel6/expected.js
deleted file mode 100644
index 9bb5e75..0000000
--- a/test/fixtures/babel6/expected.js
+++ /dev/null
@@ -1,13 +0,0 @@
-'use strict';
-
-assert(assert._expr(assert._capt(falsyStr, 'arguments/0'), {
-  content: 'assert(falsyStr)',
-  filepath: 'test/fixtures/babel6/fixture.js',
-  line: 3
-}));
-
-assert(assert._expr(assert._capt(falsyStr, 'arguments/0'), {
-  content: 'assert(falsyStr, messageStr)',
-  filepath: 'test/fixtures/babel6/fixture.js',
-  line: 5
-}), messageStr);
diff --git a/test/fixtures/babel6/fixture.js b/test/fixtures/babel6/fixture.js
deleted file mode 100644
index 19cc388..0000000
--- a/test/fixtures/babel6/fixture.js
+++ /dev/null
@@ -1,5 +0,0 @@
-'use strict';
-
-assert(falsyStr);
-
-assert(falsyStr, messageStr);
diff --git a/test/test.js b/test/test.js
index 2b1eafc..d631225 100644
--- a/test/test.js
+++ b/test/test.js
@@ -10,6 +10,7 @@ function testTransform (fixtureName, extraOptions) {
         var fixtureFilepath = path.resolve(__dirname, 'fixtures', fixtureName, 'fixture.js');
         var expectedFilepath = path.resolve(__dirname, 'fixtures', fixtureName, 'expected.js');
         var result = babel.transformFileSync(fixtureFilepath, extend({
+            presets: ['es2015'],
             plugins: ['../index']
         }, extraOptions));
         var actual = result.code;
@@ -18,48 +19,44 @@ function testTransform (fixtureName, extraOptions) {
     });
 }
 
-describe('babel6 challenge', function () {
-    testTransform('babel6');
+describe('babel-plugin-espower', function () {
+    testTransform('NonTarget');
+    testTransform('Literal');
+    testTransform('Identifier');
+    testTransform('BinaryExpression');
+    testTransform('UnaryExpression');
+    testTransform('LogicalExpression');
+    testTransform('MemberExpression');
+    testTransform('CallExpression');
+    testTransform('AssignmentExpression');
+    testTransform('ArrayExpression');
+    testTransform('UpdateExpression');
+    testTransform('ConditionalExpression');
+    testTransform('ObjectExpression');
+    testTransform('NewExpression');
+    testTransform('FunctionExpression');
+    testTransform('TemplateLiteral');
+    testTransform('TaggedTemplateExpression');
+    testTransform('ArrowFunctionExpression');
+    testTransform('ClassExpression');
+    testTransform('SpreadElement');
+    testTransform('Property');
+    testTransform('inputSourceMap', {
+        plugins: [
+            createEspowerPlugin(babel, {
+                sourceRoot: "/absolute/"
+            })
+        ]
+    });
+    testTransform('customPatterns', {
+        plugins: [
+            createEspowerPlugin(babel, {
+                patterns: [
+                    'assert.isNull(object, [message])',
+                    'assert.same(actual, expected, [message])',
+                    'assert.near(actual, expected, delta, [message])'
+                ]
+            })
+        ]
+    });
 });
-
-// describe('babel-plugin-espower', function () {
-//     testTransform('NonTarget');
-//     testTransform('Literal');
-//     testTransform('Identifier');
-//     testTransform('BinaryExpression');
-//     testTransform('UnaryExpression');
-//     testTransform('LogicalExpression');
-//     testTransform('MemberExpression');
-//     testTransform('CallExpression');
-//     testTransform('AssignmentExpression');
-//     testTransform('ArrayExpression');
-//     testTransform('UpdateExpression');
-//     testTransform('ConditionalExpression');
-//     testTransform('ObjectExpression');
-//     testTransform('NewExpression');
-//     testTransform('FunctionExpression');
-//     testTransform('TemplateLiteral');
-//     testTransform('TaggedTemplateExpression');
-//     testTransform('ArrowFunctionExpression');
-//     testTransform('ClassExpression');
-//     testTransform('SpreadElement');
-//     testTransform('Property');
-//     testTransform('inputSourceMap', {
-//         plugins: [
-//             createEspowerPlugin(babel, {
-//                 sourceRoot: "/absolute/"
-//             })
-//         ]
-//     });
-//     testTransform('customPatterns', {
-//         plugins: [
-//             createEspowerPlugin(babel, {
-//                 patterns: [
-//                     'assert.isNull(object, [message])',
-//                     'assert.same(actual, expected, [message])',
-//                     'assert.near(actual, expected, delta, [message])'
-//                 ]
-//             })
-//         ]
-//     });
-// });