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,…
