Writing Simple Unit-Tests with JUnit

In the Loklak Server project, we use a number of automation tools like the build testing tool ‘TravisCI’, automated code reviewing tool ‘Codacy’, and ‘Gemnasium’. We are also using JUnit, a java-based unit-testing framework for writing automated Unit-Tests for java projects. It can be used to test methods to check their behaviour whenever there is any change in implementation. These unit-tests are handy and are coded specifically for the project. In the Loklak Server project it is used to test the web-scrapers. Generally JUnit is used to check if there is no change in behaviour of the methods, but in this project, it also helps in keeping check if the website code has been modified, affecting the data that is scraped.

Let’s start with basics, first by setting up, writing a simple Unit-Tests and then Test-Runners. Here we will refer how unit tests have been implemented in Loklak Server to familiarize with the JUnit Framework.

Setting-UP

Setting up JUnit with gradle is easy, You have to do just 2 things:-

1) Add JUnit dependency in build.gradle

Dependencies {

. . .

. . .<other compile groups>. . .

compile group: 'com.twitter', name: 'jsr166e', version: '1.1.0'

compile group: 'com.vividsolutions', name: 'jts', version: '1.13'

compile group: 'junit', name: 'junit', version: '4.12'

compile group: 'org.apache.logging.log4j', name: 'log4j-1.2-api', version: '2.6.2'

compile group: 'org.apache.logging.log4j', name: 'log4j-api', version: '2.6.2'

. . .

. . .

}

 

2) Add source for ‘test’ task from where tests are built (like here).

Save all tests in test directory and keep its internal directory structure identical to src directory structure. Now set the path in build.gradle so that they can be compiled.

sourceSets.test.java.srcDirs = ['test']

 

Writing Unit-Tests

In JUnit FrameWork a Unit-Test is a method that tests a particular behaviour of a section of code. Test methods are identified by annotation @Test.

Unit-Test implements methods of source files to test their behaviour. This can be done by fetching the output and comparing it with expected outputs.

The following test tests if twitter url that is created is valid or not that is to be scraped.

/**

 * This unit-test tests twitter url creation

 */

@Test

public void testPrepareSearchURL() {

String url;

String[] query = {"fossasia", "from:loklak_test",

"spacex since:2017-04-03 until:2017-04-05"};

String[] filter = {"video", "image", "video,image", "abc,video"};

String[] out_url = {

"https://twitter.com/search?f=tweets&vertical=default&q=fossasia&src=typd",

"https://twitter.com/search?f=tweets&vertical=default&q=from%3Aloklak_test&src=typd",

"and other output url strings to be matched…..."

};


// checking simple urls

for (int i = 0; i < query.length; i++) {

url = TwitterScraper.prepareSearchURL(query[i], "");


//compare urls with urls created

assertThat(out_url[i], is(url));

}


// checking urls having filters

for (int i = 0; i < filter.length; i++) {

url = TwitterScraper.prepareSearchURL(query[0], filter[i]);


//compare urls with urls created

assertThat(out_url[i+3], is(url));

}

}

 

Testing the implementation of code is useless as it will either make code more difficult to change or tests useless  . So be cautious while writing tests and keep difference between Implementation and Behaviour in mind.

This is the perfect example for a simple Unit-Test. As we see there are some points, which needs to be observed like:-

1) There is a annotation @Test .

2) Input array of query which is fed to the method TwitterScraper.prepareSearchURL() .

3) Array of urls out_url[], which are the expected urls to output.

4) asserThat() to compare the expected url (in array out_url[]) and the output url (in variable ‘url’).

NOTE: assertEquals() could also be used here, but we prefer to use assert methods to get error message that is readable (We will discuss about this some time later)

And the TestRunner

When we are working on a project, It is not feasible to run tests using gradle as they are first built  (else verified whether tests are build-ready) and then executed. gradle test shall be used only for building and testing the tests. For testing the project, one shall set-up TestRunner. It allows to run specific set of tests, one wants to run.

TestRunners are built once using gradle (with other tests) and can be run whenever you want. Also it is easy to stack up the test classes you want to run in SuiteClasses and @RunWith to run SuiteClasses with the TestRunner.

In loklak server, TestRunner runs the web-scraper tests. They are used by developers to test the changes they have made.

This is a sample TestRunner, code link here .

package org.loklak;


// Library classes imported

import org.junit.runner.RunWith;

import org.junit.runners.Suite;

// Source files to be tested

import org.loklak.harvester.TwitterScraperTest;

import org.loklak.harvester.YoutubeScraperTest;


/*

* TestRunner for harvesters

*/

@RunWith(Suite.class)

@Suite.SuiteClasses({

TwitterScraperTest.class,

YoutubeScraperTest.class

})

public class TestRunner {

}

 

You can also add TestRunners for different sections of the project. Like here it is initialized only to test harvesters.

To run the TestRunner

Add classpath of the jar file of the project and run ‘JUnitCore’ with TestRunner to get output on terminal.

java -classpath .:build/libs/<yourProject>.jar:build/classes/test org.junit.runner.JUnitCore org.loklak.TestRunner

In the project we have set up a shell script to run the tests.

Few points

1) Build the project and tests separately. Build tests only when changed as they take time to be built and executed.

2) Whenever you are done with the coding part, run the tests using TestRunner.

3) Write unit-tests whenever you add a new feature to the project to keep it up-to-date.

Now lets end up here.

So for now, Code it, Test it and Repeat.

Resources:

Join the FOSSASIA Community Network

The FOSSASIA.net project is an initiative to bring the Asian Free and Open Source Software and OpenTech community together and foster cooperation. We make it easy to find communities and projects on a map with links to the websites, social media channels, and automatically updated info from community blogs.

Communities store their information decentrally anywhere on the web – on their server, a blog, or git service. FOSSASIA.net collects information through a stardardized API file on the web. You can generate the API file with the FOSSASIA API generator on our website. Then you add your community to the FOSSASIA network website. Simply add the link of your API file to our list of communities on github.

FAQ

How does it work?
You need to provide a file for our API and add the file to our communities repository. Then fill in the link to your API on our directory on github. That is it!

Where can I store my file?
We prefer that you store your file in our github repository of communities: https://github.com/fossasia/fossasia-communities. It is also possible to store it anywhere on the web, where it is publicly available, e.g. in a blog or CMS page as an attachment. However the github repo is the preferred method currently.

How about updating my file?
If you need to update your links, just upload a new file in the same location.

How do I start?
To make it easier, we created a FOSSASIA API Generator, where you can simply fill in your data here: http://api.fossasia.org/generator When you are finished copy the info from the form on the top right into an empty file or use the download button.

How do I find Geolocation data of my community?
You can find this data from OpenStreetmap. OpenStreetmap shows maps using a URL of the form: www.openstreetmap.org/#map=[Zoom Level]/[Latitude]/[Longitude] So go to www.openstreetmap.org and zoom to the area of your community. For example, if you are zoom into Mumbai, you will get the URL http://www.openstreetmap.org/#map=11/19.0715/72.9499 Then 19.0715 will be the latitude and 72.9499 the longitude.

What is an API?
In computer programming, an application programming interface (API) is a set of routines, protocols, and tools for building software applications. An API expresses a software component in terms of its operations, inputs, outputs, and underlying types. An API defines functionalities that are independent of their respective implementations (e.g. It does not matter what CMS is used), which allows definitions and implementations to vary without compromising each other. Compare: en.wikipedia.org/wiki/Application_programming_interface

Links

* Website http://fossasia.net

* Map http://fossasia.net/map/map.html

* FOSSASIA Community Network Tweets https://twitter.com/fantwk