Kraken

Kraken is an open source automated android and web E2E testing tool that supports and validates scenarios that involve the inter-communication between two or more users. It works in a Black Box manner meaning that it is not required to have access to the source code of the application but instead it can be run with the APK (Android package file format) and web page URL. Kraken uses signaling for coordinating the communication between the devices using a file based protocol.

Video

Kraken is partially supported by a Google Latin America Research Award (LARA) 2018 - 2021

Technologies

Kraken uses Appium and WebdriverIO for running automated E2E tests in each device or emulator and Cucumber for running your feature files written with Gherkin sintax.

🔨 Installation

Prerequisites

Android SDK (ADB and AAPT configured)
Appium
NodeJS (Version ≥ 12)
Java

Check if all prerequisites are installed

Kraken offers the following command to check if all required configuration before running Kraken is installed correctly.

kraken-node doctor

Signaling

Signaling is a protocol used for the communication of two or more devices running in parallel. It is based in the idea that each browser, emulator or real device has a communication channel where he can receive signals sent from other devices which contain information or actions that are supposed to be executed. This type of protocol is commonly used in automated mobile E2E testing tools that validate scenarios involving the inter-communication and collaboration of two or more applications.

Writing your first test

Create NodeJS project

npm init -y

Install Kraken

npm install kraken-node --save

Generate cucumber feature skeleton

You need to generate the cucumber feature skeleton where your tests are going to be saved. To achieve this you should run.

npx kraken-node gen

This will create the following folders and files.

features
|_mobile
| |_step_definitions
| | |_step.js
| |_support
| | |_hooks.js
| | |_support.js
|_web
| |_step_definitions
| | |_step.js
| |_support
| | |_hooks.js
| | |_support.js
|_my_first.feature
mobile.json

Executing the test

To execute the test you should run the following command.

npx kraken-node run

Syntax

In Kraken each feature is a test and each scenario within a feature is a test case that is run in a device. Each device is identified as an user and numbered from 1 to N. Ex: @user1, @user2, @user3. Also you each user should specify what type of device is going to execute the scenario, for web testing use @web and for mobile testing use @mobile.

After identifying what number each device has, you can write your test case giving each scenario the tag of a given device like so:

Feature: Example feature

  @user1 @mobile
  Scenario: As a first user I say hi to a second  user
  Given I wait
  Then I send a signal to user 2 containing "hi"

  @user2 @web
  Scenario: As a second user I wait for user 1  to say hi
  Given I wait for a signal containing "hi"
  Then I wait

Kraken steps

Kraken offers two main steps to help synchronizing your devices.

Signaling steps

To wait for a signal coming from another device for 10 seconds that is Kraken default timeout use the following step.

Then /^I wait for a signal containing "([^\"]*)"$/

To wait for a signal coming from another device for an specified number of seconds use the following step

Then /^I wait for a signal containing "(  [^\"]*)" for (\d+) seconds$/

To send a signal to another specified device use the following step

Then /^I send a signal to user (\d+) containing "([^\"]*)"$/

Signaling functions

Each device has an internal Kraken implementation of the signaling steps using the following functions.

readSignal(content, time_out)

Waits for a signal with the specified content. This functions waits for the specified number of seconds in the timeout parameter before throwing an exception if specified.

writeSignal(signal)

Writes signal content to a device inbox.

Creating new steps

To create new steps it depends the platform that is going to implement the step, in the case of Mobile testing you should add your custom steps on the features/mobile/step_definitions/step.js file. On the other hand, when adding a custom step for Web testing you should add the step in the file features/web/step_definitions/step.js.

Take into account that Kraken uses Webdriverio for executing mobile and web steps so it is necessary to follow it's syntax, you can learn more about Webdriverio at the following link

📱Kraken Mobile

Mobile steps

To see a list of all mobile steps available in Kraken, visit the following link

Specifying Android's APK file for the test

In case you are going to execute mobile testing with or instead of web testing you should specify an APK file that will be installed on the phone available for testing, also Appium requires the name of the package and main activity of the app under test. To achieve this Kraken creates a file named mobile.json on the root directory where you can specify this information.

{
    "type": "singular",
    "apk_path": "<APK_PATH>",
    "apk_package": "<APK_PACKAGE>",
    "apk_launch_activity": "<APK_LAUNCH_ACTIVITY>"
}

To run different APK files on every device you only need to change the mobile.json content to match the following format:

{
    "type": "multiple",
    "@user1": {
      "apk_path": "<APK_PATH>",
      "apk_package": "<APK_PACKAGE>",
      "apk_launch_activity": "<APK_LAUNCH_ACTIVITY>"
    },
    "@user2": {
      "apk_path": "<APK_PATH>",
      "apk_package": "<APK_PACKAGE>",
      "apk_launch_activity": "<APK_LAUNCH_ACTIVITY>"
    }
}

Notice that the content of every key @userN where N is the ID of the user, specifies the APK information that will run each user.

Finding your apps package and launch activity name

In most cases when testing a third party app you will not have the APK's package and launch activity, that is why Kraken offers the following command that using Android's ADB will try to retrieve this information from the APK.

npx kraken-node apk-info <APK_PATH>

🦍 Mobile Monkey execution

Kraken offers the possibility of generating random GUI events by using Android ADB monkey as well as its own implementation based in the idea of sending and reading random signals.

Android’s ADB Monkey

To execute ADB monkey Kraken offers the following command specifying the number of events to be executed:

Then I start a monkey with (\d+) events

Kraken’s own monkey

Kraken extended the ADB monkey behavior by executing GUI events only in buttons and clickable views or inputs by offering the following command:

Then I start kraken monkey with (\d+) events

XML snapshot

Kraken makes it possible to save the XML presented by the current view in a specific device, this is convenient to identify view ids, asserting the correct XML is presented after an action has being completed or running static analyzing tools.

Saving the snapshot

To save the snapshot of the current view, Kraken offers the following step specifying where the file is going to be saved:

Then I save device snapshot in file with path "([^\"]*)"

🌎 Kraken Web

Kraken is extended to run also in web browsers and orchestrate the communication with other browsers running different websites or mobile applications that are being executed on physical devices or emulators. With the help of ChromeDriver/Geckodriver and Cucumber we run test scenarios using Gherkin syntax as well as Kraken predefined signaling steps described before.

Web steps

To see a list of all web steps available in Kraken, visit the following link

Specifying in what browser Kraken will run

Kraken uses ChromeDriver and Chrome as default web browser but provides support for Firefox and Geckodriver. To specify that your test is going to be run in Firefox change the parameter passed to the WebClient class on the file located at features/web/support/hooks.js as shown in the snippet:

this.deviceClient = new WebClient('firefox', {}, this.userId);

🦍 Web Monkey execution

Kraken has implemented it's own monkey behavior by executing random GUI events in buttons, clickable views and inputs by offering the following command:

Then I start kraken monkey with (\d+) events

🗯 Extended Kraken functionalities

In the following sections we provide specification for shared functionality between Kraken mobile and web as well as some examples of Kraken in action.

Properties file

Kraken uses properties files to store sensitive data such as passwords or API keys that should be used in your test cases.

Generate properties file

The properties files should be a manually created JSON file with the following structure and location in the root directory with the name properties.json

{
    "PASSWORD": "test",
    "API_KEY": "test2"
}

Use properties file in your test

You can use the specified properties using the following sintax.

@user1
Scenario: As a user
    Given I wait
    Then I see the text "<PASSWORD>"

Specifying that your custom step uses Kraken properties

If you specify new steps for web or mobile and require them to use Kraken properties functionality you should use the Cucumber property {kraken-string} instead of {string} as shown in the following snippet:

When('I navigate to page {kraken-string}', async function (page) {
    return await this.driver.url(page);
});

Use fake strings in tests

Kraken offers a Fake string generator thanks to the NPM package @faker-js/faker, the list of supported faker types are listed as follows:

Name
Number
Email
String
String Date
URL

Use a faker in a test

Kraken keeps a record of every Fake string generated, thats why each string will have an id associated. To generate a Faker string you need to follow the structure “$FAKERNAME_ID”.

@user1
Scenario: As a user
    Given I wait
    Then I enter text "$name_1" into field with id "view"

Specifying that your custom step uses Kraken faker

If you specify new steps for web or mobile and require them to use Kraken faker functionality you should use the Cucumber property {kraken-string} instead of {string} as shown in the following snippet:

When('I navigate to page {kraken-string}', async function (page) {
    return await this.driver.url(page);
});

Reusing a fake string

As mentioned before, Kraken keeps record of every string generated with an id given to each string, this gives you the possibility of reusing this string later in your scenario. To reuse a string you can you need to append a $ character to the fake string as follows:

@user1
Scenario: As a user
    Given I wait
    Then I enter text "$name_1" into field with id "view"
    Then I press "add_button"
    Then I should see "$$name_1"

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