diff --git a/.eslintrc b/.eslintrc
index 9300a97..d962771 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -1,5 +1,8 @@
 {
   "extends": [
     "wesbos"
-  ]
+  ],
+  "rules": {
+    "new-cap": "off"
+  }
 }
\ No newline at end of file
diff --git a/README.md b/README.md
index c5049d7..7bf0ea9 100644
--- a/README.md
+++ b/README.md
@@ -1,27 +1,19 @@
 # ewelink-api
 > eWeLink API for Node.js
 
+
 ## Installation
 ``` sh
  npm install ewelink-api
 ```
 
+
 ## Usage
-```
-const ewelink = require('ewelink-api');
+Check `demo/` directory for examples.
 
-(async () => {
 
-  const conn = new ewelink({
-    email: '<your ewelink email>',
-    password: '<your ewelink password>',
-  });
+## Testing
+1. open `test/_setup/credentials.json` and update parameters.
+2. in a terminal, `npm run test`
 
-  /* get all devices */
-  const devices = await conn.getDevices();
-  console.log(devices);
-
-})();
-```
-
-Check `demo/` directory for more examples.
\ No newline at end of file
+* Tests needs to be performed serially, so if run jest manually, add `--runInBand` parameter.
\ No newline at end of file
diff --git a/lib/ewelink-helper.js b/lib/ewelink-helper.js
index d061724..d2c28a7 100644
--- a/lib/ewelink-helper.js
+++ b/lib/ewelink-helper.js
@@ -146,10 +146,9 @@ const getDeviceChannelCountByType = deviceType => {
   return DEVICE_CHANNEL_LENGTH[deviceType] || 0;
 };
 
-const getDeviceTotalChannels = deviceUUID => {
+const getDeviceChannelCount = deviceUUID => {
   const deviceType = getDeviceTypeByUiid(deviceUUID);
-  const channels = getDeviceChannelCountByType(deviceType);
-  return channels;
+  return getDeviceChannelCountByType(deviceType);
 };
 
 module.exports = {
@@ -157,5 +156,5 @@ module.exports = {
   loginPayload,
   wssLoginPayload,
   wssUpdatePayload,
-  getDeviceTotalChannels,
+  getDeviceChannelCount,
 };
diff --git a/main.js b/main.js
index bce30d7..62901ca 100644
--- a/main.js
+++ b/main.js
@@ -10,7 +10,7 @@ const {
   loginPayload,
   wssLoginPayload,
   wssUpdatePayload,
-  getDeviceTotalChannels,
+  getDeviceChannelCount,
 } = require('./lib/ewelink-helper');
 
 class eWeLink {
@@ -112,7 +112,7 @@ class eWeLink {
   async getDevicePowerState(deviceId, channel = 1) {
     const device = await this.getDevice(deviceId);
     const error = _get(device, 'error', false);
-    const switchesAmount = getDeviceTotalChannels(device.uiid);
+    const switchesAmount = getDeviceChannelCount(device.uiid);
     let state = _get(device, 'params.switch', false);
     const switches = _get(device, 'params.switches', false);
 
@@ -133,7 +133,7 @@ class eWeLink {
   async setDevicePowerState(deviceId, state, channel = 1) {
     const device = await this.getDevice(deviceId);
     const error = _get(device, 'error', false);
-    const switchesAmount = getDeviceTotalChannels(device.uiid);
+    const switchesAmount = getDeviceChannelCount(device.uiid);
     const status = _get(device, 'params.switch', false);
     const switches = _get(device, 'params.switches', false);
 
@@ -183,19 +183,7 @@ class eWeLink {
 
     const newState = state === 'on' ? 'off' : 'on';
 
-    const newResponse = await this.setDevicePowerState(
-      deviceId,
-      newState,
-      channel
-    );
-
-    return newResponse;
-  }
-
-  async getDeviceChannelCount(deviceId) {
-    const device = await this.getDevice(deviceId);
-    const switchesAmount = getDeviceTotalChannels(device.uiid);
-    return switchesAmount;
+    return this.setDevicePowerState(deviceId, newState, channel);
   }
 }
 
diff --git a/package-lock.json b/package-lock.json
index 794b93b..efbd224 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "ewelink-api",
-  "version": "1.2.0",
+  "version": "1.2.1",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index 77c2af0..2046fb6 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "ewelink-api",
-  "version": "1.2.0",
+  "version": "1.2.1",
   "description": "eWeLink API for Node.js",
   "author": "Martín M.",
   "license": "MIT",
@@ -20,8 +20,7 @@
   ],
   "main": "main.js",
   "scripts": {
-    "demo": "node ./demo/example.js",
-    "test": "jest --testPathIgnorePatterns '(node_modules|.cache)'"
+    "test": "jest --runInBand --verbose --testPathIgnorePatterns '(node_modules|.cache)'"
   },
   "dependencies": {
     "delay": "^4.3.0",
diff --git a/test/credentials.json b/test/_setup/credentials.json
similarity index 100%
rename from test/credentials.json
rename to test/_setup/credentials.json
diff --git a/test/_expectations.js b/test/_setup/expectations.js
similarity index 100%
rename from test/_expectations.js
rename to test/_setup/expectations.js
diff --git a/test/main-env-node.spec.js b/test/main-env-node.spec.js
new file mode 100644
index 0000000..1df68fc
--- /dev/null
+++ b/test/main-env-node.spec.js
@@ -0,0 +1,72 @@
+const ewelink = require('../main');
+const { email, password, deviceId } = require('./_setup/credentials.json');
+const {
+  loginExpectations,
+  allDevicesExpectations,
+  specificDeviceExpectations,
+} = require('./_setup/expectations');
+
+describe('env: node script', () => {
+  let conn;
+
+  beforeAll(() => {
+    conn = new ewelink({ email, password });
+  });
+
+  test('login into ewelink', async () => {
+    const login = await conn.login();
+    expect(typeof login).toBe('object');
+    expect(login).toMatchObject(loginExpectations);
+  });
+
+  test('get all devices', async () => {
+    const devices = await conn.getDevices();
+    expect(Array.isArray(devices)).toBe(true);
+    expect(devices[0]).toMatchObject(allDevicesExpectations);
+  });
+
+  test('get specific device', async () => {
+    const device = await conn.getDevice(deviceId);
+    expect(typeof device).toBe('object');
+    expect(device.deviceid).toBe(deviceId);
+    expect(device).toMatchObject(specificDeviceExpectations);
+  });
+
+  test('get device power state', async () => {
+    const device = await conn.getDevice(deviceId);
+    const currentState = device.params.switch;
+    const powerState = await conn.getDevicePowerState(deviceId);
+    expect(typeof powerState).toBe('object');
+    expect(powerState.status).toBe('ok');
+    expect(powerState.state).toBe(currentState);
+  });
+
+  test('set device power state', async () => {
+    jest.setTimeout(30000);
+    const device = await conn.getDevice(deviceId);
+    const currentState = device.params.switch;
+    const newState = currentState === 'on' ? 'off' : 'on';
+    const powerState = await conn.setDevicePowerState(deviceId, newState);
+    expect(typeof powerState).toBe('object');
+    expect(powerState.status).toBe('ok');
+    expect(powerState.state).toBe(newState);
+    const deviceVerify = await conn.getDevice(deviceId);
+    const currentStateVerify = deviceVerify.params.switch;
+    expect(newState).toBe(currentStateVerify);
+  });
+
+  test('toggle device power state', async () => {
+    jest.setTimeout(30000);
+    const device = await conn.getDevice(deviceId);
+    const currentState = device.params.switch;
+    const newState = currentState === 'on' ? 'off' : 'on';
+    await conn.toggleDevice(deviceId);
+    const deviceVerify = await conn.getDevice(deviceId);
+    const currentStateVerify = deviceVerify.params.switch;
+    expect(newState).toBe(currentStateVerify);
+    await conn.toggleDevice(deviceId);
+    const deviceVerifyAgain = await conn.getDevice(deviceId);
+    const currentStateVerifyAgain = deviceVerifyAgain.params.switch;
+    expect(currentState).toBe(currentStateVerifyAgain);
+  });
+});
diff --git a/test/main-env-serverless.spec.js b/test/main-env-serverless.spec.js
new file mode 100644
index 0000000..68e4827
--- /dev/null
+++ b/test/main-env-serverless.spec.js
@@ -0,0 +1,77 @@
+const ewelink = require('../main');
+const { email, password, deviceId } = require('./_setup/credentials.json');
+const {
+  loginExpectations,
+  allDevicesExpectations,
+  specificDeviceExpectations,
+} = require('./_setup/expectations');
+
+describe('env: serverless', () => {
+  let accessToken;
+  let apiKey;
+
+  test('login into ewelink', async () => {
+    const conn = new ewelink({ email, password });
+    const login = await conn.login();
+    accessToken = login.at;
+    apiKey = login.user.apikey;
+    expect(typeof login).toBe('object');
+    expect(login).toMatchObject(loginExpectations);
+  });
+
+  test('get all devices', async () => {
+    const conn = new ewelink({ at: accessToken });
+    const devices = await conn.getDevices();
+    expect(Array.isArray(devices)).toBe(true);
+    expect(devices[0]).toMatchObject(allDevicesExpectations);
+  });
+
+  test('get specific device', async () => {
+    const conn = new ewelink({ at: accessToken });
+    const device = await conn.getDevice(deviceId);
+    expect(typeof device).toBe('object');
+    expect(device.deviceid).toBe(deviceId);
+    expect(device).toMatchObject(specificDeviceExpectations);
+  });
+
+  test('get device power state', async () => {
+    const conn = new ewelink({ at: accessToken });
+    const device = await conn.getDevice(deviceId);
+    const currentState = device.params.switch;
+    const powerState = await conn.getDevicePowerState(deviceId);
+    expect(typeof powerState).toBe('object');
+    expect(powerState.status).toBe('ok');
+    expect(powerState.state).toBe(currentState);
+  });
+
+  test('set device power state', async () => {
+    jest.setTimeout(30000);
+    const conn = new ewelink({ at: accessToken, apiKey });
+    const device = await conn.getDevice(deviceId);
+    const currentState = device.params.switch;
+    const newState = currentState === 'on' ? 'off' : 'on';
+    const powerState = await conn.setDevicePowerState(deviceId, newState);
+    expect(typeof powerState).toBe('object');
+    expect(powerState.status).toBe('ok');
+    expect(powerState.state).toBe(newState);
+    const deviceVerify = await conn.getDevice(deviceId);
+    const currentStateVerify = deviceVerify.params.switch;
+    expect(newState).toBe(currentStateVerify);
+  });
+
+  test('toggle device power state', async () => {
+    jest.setTimeout(30000);
+    const conn = new ewelink({ at: accessToken, apiKey });
+    const device = await conn.getDevice(deviceId);
+    const currentState = device.params.switch;
+    const newState = currentState === 'on' ? 'off' : 'on';
+    await conn.toggleDevice(deviceId);
+    const deviceVerify = await conn.getDevice(deviceId);
+    const currentStateVerify = deviceVerify.params.switch;
+    expect(newState).toBe(currentStateVerify);
+    await conn.toggleDevice(deviceId);
+    const deviceVerifyAgain = await conn.getDevice(deviceId);
+    const currentStateVerifyAgain = deviceVerifyAgain.params.switch;
+    expect(currentState).toBe(currentStateVerifyAgain);
+  });
+});
diff --git a/test/main-invalid-credentials.spec.js b/test/main-invalid-credentials.spec.js
new file mode 100644
index 0000000..c2c3f19
--- /dev/null
+++ b/test/main-invalid-credentials.spec.js
@@ -0,0 +1,51 @@
+const ewelink = require('../main');
+const { deviceId } = require('./_setup/credentials.json');
+
+describe('invalid credentials', () => {
+  test('no credentials given', async () => {
+    const conn = new ewelink({});
+    expect(typeof conn).toBe('object');
+    expect(conn.error).toBe('No credentials provided');
+  });
+
+  test('get error response on api login', async () => {
+    const conn = new ewelink({ email: 'invalid', password: 'credentials' });
+    const login = await conn.login();
+    expect(typeof login).toBe('object');
+    expect(login.msg).toBe('Authentication error');
+    expect(login.error).toBe(400);
+  });
+
+  test('get error response on all devices', async () => {
+    const conn = new ewelink({ email: 'invalid', password: 'credentials' });
+    const devices = await conn.getDevices();
+    expect(typeof devices).toBe('object');
+    expect(devices.msg).toBe('Authentication error');
+    expect(devices.error).toBe(401);
+  });
+
+  test('get error response on specific device', async () => {
+    const conn = new ewelink({ email: 'invalid', password: 'credentials' });
+    const device = await conn.getDevice(deviceId);
+    expect(typeof device).toBe('object');
+    expect(device.msg).toBe('Authentication error');
+    expect(device.error).toBe(401);
+  });
+
+  test('get device power state should fail', async () => {
+    const conn = new ewelink({ email: 'invalid', password: 'credentials' });
+    const powerState = await conn.getDevicePowerState(deviceId);
+    expect(typeof powerState).toBe('object');
+    expect(powerState.msg).toBe('Authentication error');
+    expect(powerState.error).toBe(401);
+  });
+
+  test('set device power state should fail', async () => {
+    jest.setTimeout(30000);
+    const conn = new ewelink({ email: 'invalid', password: 'credentials' });
+    const powerState = await conn.setDevicePowerState(deviceId, 'on');
+    expect(typeof powerState).toBe('object');
+    expect(powerState.msg).toBe('Authentication error');
+    expect(powerState.error).toBe(401);
+  });
+});
diff --git a/test/main-valid-credentials.spec.js b/test/main-valid-credentials.spec.js
new file mode 100644
index 0000000..209bc47
--- /dev/null
+++ b/test/main-valid-credentials.spec.js
@@ -0,0 +1,40 @@
+const ewelink = require('../main');
+const { email, password } = require('./_setup/credentials.json');
+const { loginExpectations } = require('./_setup/expectations');
+
+describe('valid credentials, invalid device', () => {
+  test('get device power state should fail', async () => {
+    const conn = new ewelink({ email, password });
+    const powerState = await conn.getDevicePowerState('invalid deviceid');
+    expect(typeof powerState).toBe('object');
+    expect(powerState.msg).toBe('Device does not exist');
+    expect(powerState.error).toBe(500);
+  });
+
+  test('set device power state should fail', async () => {
+    jest.setTimeout(30000);
+    const conn = new ewelink({ email, password });
+    const powerState = await conn.setDevicePowerState('invalid deviceid', 'on');
+    expect(typeof powerState).toBe('object');
+    expect(powerState.msg).toBe('Device does not exist');
+    expect(powerState.error).toBe(500);
+  });
+
+  test('toggle device power state should fail', async () => {
+    jest.setTimeout(30000);
+    const conn = new ewelink({ email, password });
+    const powerState = await conn.toggleDevice('invalid deviceid');
+    expect(typeof powerState).toBe('object');
+    expect(powerState.msg).toBe('Device does not exist');
+    expect(powerState.error).toBe(500);
+  });
+});
+
+describe('valid credentials, wrong region', () => {
+  test('should login in the right region', async () => {
+    const conn = new ewelink({ email, password, region: 'eu' });
+    const login = await conn.login();
+    expect(typeof login).toBe('object');
+    expect(login).toMatchObject(loginExpectations);
+  });
+});
diff --git a/test/main.spec.js b/test/main.spec.js
deleted file mode 100644
index 2b65102..0000000
--- a/test/main.spec.js
+++ /dev/null
@@ -1,190 +0,0 @@
-const ewelink = require('../main');
-const { email, password, deviceId } = require('./credentials.json');
-const {
-  loginExpectations,
-  allDevicesExpectations,
-  specificDeviceExpectations,
-} = require('./_expectations');
-
-describe('env: node script', () => {
-  let conn;
-
-  beforeAll(() => {
-    conn = new ewelink({ email, password });
-  });
-
-  test('login into ewelink', async () => {
-    const login = await conn.login();
-    expect(typeof login).toBe('object');
-    expect(login).toMatchObject(loginExpectations);
-  });
-
-  test('get all devices', async () => {
-    const devices = await conn.getDevices();
-    expect(Array.isArray(devices)).toBe(true);
-    expect(devices[0]).toMatchObject(allDevicesExpectations);
-  });
-
-  test('get specific device', async () => {
-    const device = await conn.getDevice(deviceId);
-    expect(typeof device).toBe('object');
-    expect(device.deviceid).toBe(deviceId);
-    expect(device).toMatchObject(specificDeviceExpectations);
-  });
-
-  test('get device power state', async () => {
-    const device = await conn.getDevice(deviceId);
-    const currentState = device.params.switch;
-    const powerState = await conn.getDevicePowerState(deviceId);
-    expect(typeof powerState).toBe('object');
-    expect(powerState.status).toBe('ok');
-    expect(powerState.state).toBe(currentState);
-  });
-
-  test('set device power state', async () => {
-    jest.setTimeout(30000);
-    const device = await conn.getDevice(deviceId);
-    const currentState = device.params.switch;
-    const newState = currentState === 'on' ? 'off' : 'on';
-    const powerState = await conn.setDevicePowerState(deviceId, newState);
-    expect(typeof powerState).toBe('object');
-    expect(powerState.status).toBe('ok');
-    expect(powerState.state).toBe(newState);
-    const deviceVerify = await conn.getDevice(deviceId);
-    const currentStateVerify = deviceVerify.params.switch;
-    expect(newState).toBe(currentStateVerify);
-  });
-});
-
-describe('env: serverless', () => {
-  let accessToken;
-  let apiKey;
-
-  test('login into ewelink', async () => {
-    const conn = new ewelink({ email, password });
-    const login = await conn.login();
-    accessToken = login.at;
-    apiKey = login.user.apikey;
-    expect(typeof login).toBe('object');
-    expect(login).toMatchObject(loginExpectations);
-  });
-
-  test('get all devices', async () => {
-    const conn = new ewelink({ at: accessToken });
-    const devices = await conn.getDevices();
-    expect(Array.isArray(devices)).toBe(true);
-    expect(devices[0]).toMatchObject(allDevicesExpectations);
-  });
-
-  test('get specific device', async () => {
-    const conn = new ewelink({ at: accessToken });
-    const device = await conn.getDevice(deviceId);
-    expect(typeof device).toBe('object');
-    expect(device.deviceid).toBe(deviceId);
-    expect(device).toMatchObject(specificDeviceExpectations);
-  });
-
-  test('get device power state', async () => {
-    const conn = new ewelink({ at: accessToken });
-    const device = await conn.getDevice(deviceId);
-    const currentState = device.params.switch;
-    const powerState = await conn.getDevicePowerState(deviceId);
-    expect(typeof powerState).toBe('object');
-    expect(powerState.status).toBe('ok');
-    expect(powerState.state).toBe(currentState);
-  });
-
-  test('set device power state', async () => {
-    jest.setTimeout(30000);
-    const conn = new ewelink({ at: accessToken, apiKey });
-    const device = await conn.getDevice(deviceId);
-    const currentState = device.params.switch;
-    const newState = currentState === 'on' ? 'off' : 'on';
-    const powerState = await conn.setDevicePowerState(deviceId, newState);
-    expect(typeof powerState).toBe('object');
-    expect(powerState.status).toBe('ok');
-    expect(powerState.state).toBe(newState);
-    const deviceVerify = await conn.getDevice(deviceId);
-    const currentStateVerify = deviceVerify.params.switch;
-    expect(newState).toBe(currentStateVerify);
-  });
-});
-
-describe('valid credentials, invalid device', () => {
-  test('get device power state should fail', async () => {
-    const conn = new ewelink({ email, password });
-    const powerState = await conn.getDevicePowerState('invalid deviceid');
-    expect(typeof powerState).toBe('object');
-    expect(powerState.msg).toBe('Device does not exist');
-    expect(powerState.error).toBe(500);
-  });
-
-  test('set device power state should fail', async () => {
-    jest.setTimeout(30000);
-    const conn = new ewelink({ email, password });
-    const powerState = await conn.setDevicePowerState('invalid deviceid', 'on');
-    expect(typeof powerState).toBe('object');
-    expect(powerState.msg).toBe('Device does not exist');
-    expect(powerState.error).toBe(500);
-  });
-});
-
-describe('valid credentials, wrong region', () => {
-  test('login into ewelink should fail', async () => {
-    const conn = new ewelink({ region: 'eu', email, password });
-    expect(conn.region).toBe('eu');
-    const login = await conn.login();
-    expect(typeof login).toBe('object');
-    expect(login).toMatchObject(loginExpectations);
-    expect(conn.region).toBe('us');
-  });
-});
-
-describe('invalid credentials', () => {
-  test('no credentials given', async () => {
-    const conn = new ewelink({});
-    expect(typeof conn).toBe('object');
-    expect(conn.error).toBe('No credentials provided');
-  });
-
-  test('get error response on api login', async () => {
-    const conn = new ewelink({ email: 'invalid', password: 'credentials' });
-    const login = await conn.login();
-    expect(typeof login).toBe('object');
-    expect(login.msg).toBe('Authentication error');
-    expect(login.error).toBe(400);
-  });
-
-  test('get error response on all devices', async () => {
-    const conn = new ewelink({ email: 'invalid', password: 'credentials' });
-    const devices = await conn.getDevices();
-    expect(typeof devices).toBe('object');
-    expect(devices.msg).toBe('Authentication error');
-    expect(devices.error).toBe(401);
-  });
-
-  test('get error response on specific device', async () => {
-    const conn = new ewelink({ email: 'invalid', password: 'credentials' });
-    const device = await conn.getDevice(deviceId);
-    expect(typeof device).toBe('object');
-    expect(device.msg).toBe('Authentication error');
-    expect(device.error).toBe(401);
-  });
-
-  test('get device power state should fail', async () => {
-    const conn = new ewelink({ email: 'invalid', password: 'credentials' });
-    const powerState = await conn.getDevicePowerState(deviceId);
-    expect(typeof powerState).toBe('object');
-    expect(powerState.msg).toBe('Authentication error');
-    expect(powerState.error).toBe(401);
-  });
-
-  test('set device power state should fail', async () => {
-    jest.setTimeout(30000);
-    const conn = new ewelink({ email: 'invalid', password: 'credentials' });
-    const powerState = await conn.setDevicePowerState(deviceId, 'on');
-    expect(typeof powerState).toBe('object');
-    expect(powerState.msg).toBe('Authentication error');
-    expect(powerState.error).toBe(401);
-  });
-});