diff --git a/.babelrc b/.babelrc
new file mode 100644
index 0000000..e68d2fe
--- /dev/null
+++ b/.babelrc
@@ -0,0 +1,3 @@
+{
+  "presets": ["es2015", "stage-2", "react"]
+}
diff --git a/.gitignore b/.gitignore
index dd9400d..acede02 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,4 +3,5 @@ npm-debug.log
 
 .idea/
 node_modules/
+coverage/
 build/
diff --git a/package.json b/package.json
index 52e9fd3..9c123a0 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,8 @@
     "clean-test": "rm -rf build/test/",
     "lint": "eslint . --debug --ignore-path .gitignore && csscomb -l -v client/",
     "fix": "eslint . --fix --ignore-path .gitignore && csscomb client/",
-    "unit": "npm-run-all clean-test build:test && mocha --recursive build/test/",
+    "unit": "NODE_PATH=. mocha --compilers js:babel-register --recursive",
+    "coverage": "NODE_PATH=. istanbul cover _mocha -- --compilers js:babel-register --reporter dot --recursive",
     "test": "npm-run-all lint unit",
     "copy-public": "mkdir -p build/ && cp -r client/public/ build/public/",
     "build:test": "webpack --config webpack.test.config.js --progress",
@@ -31,6 +32,7 @@
     "babel-preset-es2015": "^6.3.13",
     "babel-preset-react": "^6.3.13",
     "babel-preset-stage-2": "^6.3.13",
+    "babel-register": "^6.5.2",
     "body-parser": "^1.14.2",
     "chai": "^3.5.0",
     "connect-redis": "^3.0.1",
@@ -48,6 +50,7 @@
     "hiredis": "^0.4.1",
     "history": "^1.17.0",
     "image-webpack-loader": "^1.6.2",
+    "istanbul": "^v1.0.0-alpha",
     "json-loader": "^0.5.4",
     "mocha": "^2.4.5",
     "mongodb": "^2.1.4",
diff --git a/test/client/components/page/page-type-todos-example.test.js b/test/client/components/page/page-type-todos-example.test.js
index 0b1c87e..fc8cb85 100644
--- a/test/client/components/page/page-type-todos-example.test.js
+++ b/test/client/components/page/page-type-todos-example.test.js
@@ -5,11 +5,16 @@ import ComponentMock from 'test/mocks/component';
 import PageTypeTodosExampleModel from 'client/components/page/mods/type/todos-example/model';
 
 let component = new ComponentMock();
-let model = new PageTypeTodosExampleModel(component);
 let sandbox = sinon.sandbox.create();
+let model;
 
 describe('PageTypeTodosExample', () => {
-  afterEach(() => sandbox.restore());
+  beforeEach(() => model = new PageTypeTodosExampleModel(component));
+
+  afterEach(() => {
+    model.destroy();
+    sandbox.restore();
+  });
 
   describe('#load()', () => {
     it('should set correct state after loading', () => {
diff --git a/test/client/components/page/page-type-welcome.test.js b/test/client/components/page/page-type-welcome.test.js
index ed2a1e2..afa486f 100644
--- a/test/client/components/page/page-type-welcome.test.js
+++ b/test/client/components/page/page-type-welcome.test.js
@@ -5,11 +5,16 @@ import ComponentMock from 'test/mocks/component';
 import PageTypeWelcomeModel from 'client/components/page/mods/type/welcome/model';
 
 let component = new ComponentMock();
-let model = new PageTypeWelcomeModel(component);
 let sandbox = sinon.sandbox.create();
+let model;
 
 describe('PageTypeWelcome', () => {
-  afterEach(() => sandbox.restore());
+  beforeEach(() => model = new PageTypeWelcomeModel(component));
+
+  afterEach(() => {
+    model.destroy();
+    sandbox.restore();
+  });
 
   describe('#load()', () => {
     it('should set correct state after loading', () => {
diff --git a/test/client/components/todos/todos-footer.test.js b/test/client/components/todos/todos-footer.test.js
index acd4ff3..dafb8d0 100644
--- a/test/client/components/todos/todos-footer.test.js
+++ b/test/client/components/todos/todos-footer.test.js
@@ -5,9 +5,13 @@ import ComponentMock from 'test/mocks/component';
 import TodosFooterModel from 'client/components/todos/elems/footer/model';
 
 let component = new ComponentMock();
-let model = new TodosFooterModel(component);
+let model;
 
 describe('TodosFooter', () => {
+  beforeEach(() => model = new TodosFooterModel(component));
+
+  afterEach(() => model.destroy());
+
   describe('on "TodosUpdatedList" event', () => {
     it('should calculate the number of uncompleted todos', () => {
       Dispatcher.emit(EVENTS.TodosUpdatedList, {
diff --git a/test/client/components/todos/todos-header.test.js b/test/client/components/todos/todos-header.test.js
index 8c0c2d0..1e22869 100644
--- a/test/client/components/todos/todos-header.test.js
+++ b/test/client/components/todos/todos-header.test.js
@@ -5,9 +5,13 @@ import ComponentMock from 'test/mocks/component';
 import TodosHeaderModel from 'client/components/todos/elems/header/model';
 
 let component = new ComponentMock();
-let model = new TodosHeaderModel(component);
+let model;
 
 describe('TodosHeader', () => {
+  beforeEach(() => model = new TodosHeaderModel(component));
+
+  afterEach(() => model.destroy());
+
   describe('on "TodosUpdatedList" event', () => {
     it('should have the checked checkbox, if all todos are completed', () => {
       Dispatcher.emit(EVENTS.TodosUpdatedList, {
diff --git a/test/client/components/todos/todos-item.test.js b/test/client/components/todos/todos-item.test.js
index 39cfd11..d5bd303 100644
--- a/test/client/components/todos/todos-item.test.js
+++ b/test/client/components/todos/todos-item.test.js
@@ -5,9 +5,13 @@ import ComponentMock from 'test/mocks/component';
 import TodosItemModel from 'client/components/todos/elems/item/model';
 
 let component = new ComponentMock({ id: 1, text: 'test' });
-let model = new TodosItemModel(component);
+let model;
 
 describe('TodosItem', () => {
+  beforeEach(() => model = new TodosItemModel(component));
+
+  afterEach(() => model.destroy());
+
   describe('#toggle(makeCompleted)', () => {
     it('should emit the "TodosToggleItem" event', done => {
       Dispatcher.once(EVENTS.TodosToggleItem, data => {
diff --git a/test/client/components/todos/todos-list.test.js b/test/client/components/todos/todos-list.test.js
index 12eea33..8202e64 100644
--- a/test/client/components/todos/todos-list.test.js
+++ b/test/client/components/todos/todos-list.test.js
@@ -7,13 +7,19 @@ import ComponentMock from 'test/mocks/component';
 import TodosListModel from 'client/components/todos/elems/list/model';
 
 let component = new ComponentMock();
-let model = new TodosListModel(component);
 let sandbox = sinon.sandbox.create();
+let model;
 
 describe('TodosList', () => {
-  beforeEach(() => component.state = { todos: [] });
+  beforeEach(() => {
+    component.state = { todos: [] };
+    model = new TodosListModel(component);
+  });
 
-  afterEach(() => sandbox.restore());
+  afterEach(() => {
+    model.destroy();
+    sandbox.restore();
+  });
 
   it('should call #addTodo(text) on the "TodosCreateItem" event', () => {
     let spy = sandbox.spy(model, 'addTodo');
@@ -238,6 +244,15 @@ describe('TodosList', () => {
   });
 
   describe('#deleteCompleted()', () => {
+    it('should not toggle todos if todos are undefined', () => {
+      let spy = sandbox.spy(API, 'remove');
+
+      component.state = {};
+      model.deleteCompleted();
+
+      expect(spy.called).to.be.false;
+    });
+
     it('should call the "/api/components/Todos" gate', () => {
       sandbox.stub(API, 'remove', gate => {
         expect(gate).to.be.equal('/api/components/Todos');
diff --git a/test/lib/api.test.js b/test/lib/api.test.js
index b4ac4c2..ba15585 100644
--- a/test/lib/api.test.js
+++ b/test/lib/api.test.js
@@ -1,7 +1,7 @@
-import 'expose?FormData!form-data';
-import 'expose?fetch!node-fetch';
 import { expect } from 'chai';
 import nock from 'nock';
+import fetch from 'node-fetch';
+import FormData from 'form-data';
 import API from 'lib/api';
 
 const HOST = 'http://test';
@@ -9,7 +9,17 @@ const PATH = '/api/component';
 const GATE = HOST + PATH;
 
 describe('API', () => {
-  afterEach(() => nock.cleanAll());
+  beforeEach(() => {
+    global.FormData = FormData;
+    global.fetch = fetch;
+  });
+
+  afterEach(() => {
+    delete global.FormData;
+    delete global.fetch;
+
+    nock.cleanAll();
+  });
 
   describe('.getQueryString(path, query)', () => {
     it('should return a correct path if query params are undefined', () => {
diff --git a/test/lib/component-model.test.js b/test/lib/component-model.test.js
index e0b64aa..b6689fa 100644
--- a/test/lib/component-model.test.js
+++ b/test/lib/component-model.test.js
@@ -5,17 +5,21 @@ import ComponentModel from 'lib/component-model';
 import ComponentMock from 'test/mocks/component';
 
 let component = new ComponentMock();
-let model = new ComponentModel(component);
 let sandbox = sinon.sandbox.create();
+let model;
 
 describe('ComponentModel', () => {
-  afterEach(() => sandbox.restore());
-
   beforeEach(() => {
+    model = new ComponentModel(component);
     component.props = { text: 'props' };
     component.state = { text: 'state' };
   });
 
+  afterEach(() => {
+    model.destroy();
+    sandbox.restore();
+  });
+
   describe('#props', () => {
     it('should return component props', () => {
       expect(model.props).to.be.deep.equal(component.props);
diff --git a/test/lib/dispatcher.test.js b/test/lib/dispatcher.test.js
index a106117..fd9302c 100644
--- a/test/lib/dispatcher.test.js
+++ b/test/lib/dispatcher.test.js
@@ -3,36 +3,37 @@ import { expect } from 'chai';
 import sinon from 'sinon';
 import Dispatcher from 'lib/dispatcher';
 
-let sandbox = sinon.sandbox.create();
+let EVENT = 'event';
+let spy;
 
 describe('Dispatcher', () => {
-  afterEach(() => sandbox.restore());
+  afterEach(() => Dispatcher.off(EVENT, spy));
 
   describe('.emit(event, data)', () => {
     it('should emit an event', () => {
-      let spy = sandbox.spy(EventEmitter.prototype, 'emit');
+      spy = sinon.spy(EventEmitter.prototype, 'emit');
 
-      Dispatcher.emit('event', 'data');
+      Dispatcher.emit(EVENT, 'data');
 
-      expect(spy.calledWithExactly('event', 'data')).to.be.true;
+      expect(spy.calledWithExactly(EVENT, 'data')).to.be.true;
     });
   });
 
   describe('.on(event, listener)', () => {
     it('should handle multiple events', () => {
-      let spy = sandbox.spy();
+      spy = sinon.spy();
 
-      Dispatcher.on('event', spy);
-      Dispatcher.emit('event');
-      Dispatcher.emit('event');
+      Dispatcher.on(EVENT, spy);
+      Dispatcher.emit(EVENT);
+      Dispatcher.emit(EVENT);
 
       expect(spy.callCount).to.be.equal(2);
     });
 
     it('should pass data to the handler', () => {
-      let spy = sandbox.spy();
+      spy = sinon.spy();
 
-      Dispatcher.on('event', spy).emit('event', 'data');
+      Dispatcher.on(EVENT, spy).emit(EVENT, 'data');
 
       expect(spy.calledWithExactly('data')).to.be.true;
     });
@@ -40,19 +41,19 @@ describe('Dispatcher', () => {
 
   describe('.once(event, listener)', () => {
     it('should handle an event once', () => {
-      let spy = sandbox.spy();
+      spy = sinon.spy();
 
-      Dispatcher.once('event', spy);
-      Dispatcher.emit('event');
-      Dispatcher.emit('event');
+      Dispatcher.once(EVENT, spy);
+      Dispatcher.emit(EVENT);
+      Dispatcher.emit(EVENT);
 
       expect(spy.callCount).to.be.equal(1);
     });
 
     it('should pass data to the handler', () => {
-      let spy = sandbox.spy();
+      spy = sinon.spy();
 
-      Dispatcher.once('event', spy).emit('event', 'data');
+      Dispatcher.once(EVENT, spy).emit(EVENT, 'data');
 
       expect(spy.calledWithExactly('data')).to.be.true;
     });
@@ -60,9 +61,9 @@ describe('Dispatcher', () => {
 
   describe('.off(event, listener)', () => {
     it('should remove an event listener', () => {
-      let spy = sandbox.spy();
+      spy = sinon.spy();
 
-      Dispatcher.on('event', spy).off('event', spy).emit('event');
+      Dispatcher.on(EVENT, spy).off(EVENT, spy).emit(EVENT);
 
       expect(spy.called).to.be.false;
     });
diff --git a/test/server/models/todos.test.js b/test/server/models/todos.test.js
index 5c5bd0b..1f9a570 100644
--- a/test/server/models/todos.test.js
+++ b/test/server/models/todos.test.js
@@ -186,23 +186,35 @@ describe('Todos model', () => {
       expect(mongodb.argumentsStack[1][0]._id).to.be.equal(SESSION_ID);
     });
 
-    it('should toggle todos and save them', () => {
+    it('should toggle selected todos and save them', () => {
       mongodb.data = [{
         items: [
           {
             id: '56b8a6a8fd0b51ae4bf72887',
             text: 'test',
             isCompleted: false
+          },
+          {
+            id: '56b8a6a8fd0b51ae4bf72888',
+            text: 'test',
+            isCompleted: false
           }
         ]
       }];
 
       return Model.toggle({ db: mongodb }, true, '56b8a6a8fd0b51ae4bf72887')
-        .then(items => expect(items).to.be.deep.equal([{
-          id: '56b8a6a8fd0b51ae4bf72887',
-          text: 'test',
-          isCompleted: true
-        }]));
+        .then(items => expect(items).to.be.deep.equal([
+          {
+            id: '56b8a6a8fd0b51ae4bf72887',
+            text: 'test',
+            isCompleted: true
+          },
+          {
+            id: '56b8a6a8fd0b51ae4bf72888',
+            text: 'test',
+            isCompleted: false
+          }
+        ]));
     });
 
     it('should build the right update query', () => {
diff --git a/test/server/providers/page-type-todos-example.test.js b/test/server/providers/page-type-todos-example.test.js
index e3326ca..5258b3f 100644
--- a/test/server/providers/page-type-todos-example.test.js
+++ b/test/server/providers/page-type-todos-example.test.js
@@ -20,4 +20,11 @@ describe('PageTypeTodosExample provider', () => {
         }
       }));
   });
+
+  it('should not fetch data if it is already defined', () => {
+    let prevData = { PageTypeTodosExample: {} };
+
+    return provider(null, prevData)
+      .then(data => expect(data.PageTypeTodosExample).to.be.equal(prevData.PageTypeTodosExample));
+  });
 });
diff --git a/test/server/providers/page-type-welcome.test.js b/test/server/providers/page-type-welcome.test.js
index fc671e6..20e32ff 100644
--- a/test/server/providers/page-type-welcome.test.js
+++ b/test/server/providers/page-type-welcome.test.js
@@ -11,4 +11,11 @@ describe('PageTypeWelcome provider', () => {
         }
       }));
   });
+
+  it('should not fetch data if it is already defined', () => {
+    let prevData = { PageTypeWelcome: {} };
+
+    return provider(null, prevData)
+      .then(data => expect(data.PageTypeWelcome).to.be.equal(prevData.PageTypeWelcome));
+  });
 });
diff --git a/test/server/providers/todos.test.js b/test/server/providers/todos.test.js
index b5b3080..bfa6ca3 100644
--- a/test/server/providers/todos.test.js
+++ b/test/server/providers/todos.test.js
@@ -14,4 +14,11 @@ describe('Todos provider', () => {
     return provider()
       .then(data => expect(data.Todos).to.be.deep.equal({ items: [] }));
   });
+
+  it('should not fetch data if it is already defined', () => {
+    let prevData = { Todos: {} };
+
+    return provider(null, prevData)
+      .then(data => expect(data.Todos).to.be.equal(prevData.Todos));
+  });
 });
diff --git a/webpack.client.config.js b/webpack.client.config.js
index ee5f96b..3667a11 100644
--- a/webpack.client.config.js
+++ b/webpack.client.config.js
@@ -55,10 +55,7 @@ module.exports = {
       {
         test: /\.jsx?$/,
         exclude: /node_modules/,
-        loader: 'babel',
-        query: {
-          presets: ['es2015', 'stage-2', 'react']
-        }
+        loader: 'babel'
       },
       {
         test: /\.css$/,
diff --git a/webpack.server.config.js b/webpack.server.config.js
index c76e58f..5e744a2 100644
--- a/webpack.server.config.js
+++ b/webpack.server.config.js
@@ -52,10 +52,7 @@ module.exports = {
       {
         test: /\.jsx?$/,
         exclude: /node_modules/,
-        loader: 'babel',
-        query: {
-          presets: ['es2015', 'stage-2', 'react']
-        }
+        loader: 'babel'
       },
       {
         test: /\.node$/,
diff --git a/webpack.test.config.js b/webpack.test.config.js
deleted file mode 100644
index 5468696..0000000
--- a/webpack.test.config.js
+++ /dev/null
@@ -1,58 +0,0 @@
-'use strict';
-
-let path = require('path');
-let glob = require('glob');
-
-const ENTRIES = glob.sync(path.join(__dirname, 'test/**/*.test.js')).reduce((entries, entry) => {
-  entries[path.relative(path.join(__dirname, 'test'), entry)] = entry;
-
-  return entries;
-}, {});
-
-module.exports = {
-  entry: ENTRIES,
-
-  output: {
-    path: path.join(__dirname, 'build', 'test'),
-    filename: '[name]',
-    libraryTarget: 'commonjs2'
-  },
-
-  target: 'node',
-
-  node: {
-    console: false,
-    global: false,
-    process: false,
-    Buffer: false,
-    __filename: false,
-    __dirname: false
-  },
-
-  cache: true,
-
-  resolve: {
-    root: __dirname
-  },
-
-  module: {
-    loaders: [
-      {
-        test: /\.jsx?$/,
-        exclude: /node_modules/,
-        loader: 'babel',
-        query: {
-          presets: ['es2015', 'stage-2']
-        }
-      },
-      {
-        test: /\.node$/,
-        loader: 'node'
-      },
-      {
-        test: /\.json$/,
-        loader: 'json'
-      }
-    ]
-  }
-};