Selenium - Data Driven Testing

31 Mar 2014

Data driven testing is a technique that drives tests with data. Data driven tests externalize the test data in a file or in a database.

Web applications often have a large number of edge cases that need to be tested. Fifty tests in a JUnit test case is hard to maintain. By puting the test data in an external file it can be edited by developers, testers, and buisness analyst who may not be comfortable with a programming language.

JUnit Example

Testing for broken links is a repetitive task that does not involve much logic. When testing a link we need to know what page we start on, what link we click on, and the title of the next page rendered. This can be summarized in a csv file.

http://www.google.com/intl/en/about/products/,Web Search,Inside Search – Google

In this case we are testing the links on google's products page.

To read this data into our JUnit test we add @RunWith(Parameterized.class). A static method annotated with @Parameters provides the test data from an external source. The name attribute in the @Parameters annotation defines the test name. We the annotate the instance variables to be populated with @Parameter. More information about Parameterized can be found here.

@RunWith(Parameterized.class)
public class LinkTest {

    private WebDriver driver;
    private WebDriverWait wait;
    private static final Pattern COMMA = Pattern.compile(",");

    @Parameter(0)
    public String url;

    @Parameter(1)
    public String linkText;

    @Parameter(2)
    public String expectedTitle;

    @Parameters(name = "{index}: link[{1}] -> title[{2}]")
    public static Collection<String[]> data() throws IOException {
        List<String> lines = FileUtils.readLines(new File("links.csv"));
        List<String[]> csvData = new LinkedList<String[]>();
        for (String line : lines) {
            csvData.add(COMMA.split(line));
        }
        return csvData;
    }

    @Before
    public void setUp() throws Exception {
        driver = new FirefoxDriver();
        driver.manage().timeouts().implicitlyWait(5, TimeUnit.SECONDS);
        wait = new WebDriverWait(driver, 10);
    }

    @After
    public void tearDown() throws Exception {
        driver.quit();
    }

    @Test
    public void testLink() {
        driver.get(url);
        driver.findElement(By.partialLinkText(linkText)).click();
        wait.until(ExpectedConditions.titleIs(expectedTitle));
        assertEquals(expectedTitle, driver.getTitle());
    }

}

The full project can be found on github. The static method limits JUnit to one test case per class.

TestNG Example

TestNG is more robust than JUnit for data driven testing. TestNG can have multiple data sources per test.

package jesg;

import static org.testng.Assert.assertEquals;

import java.io.File;
import java.io.IOException;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.regex.Pattern;

import org.apache.commons.io.FileUtils;
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.Wait;
import org.openqa.selenium.support.ui.WebDriverWait;
import org.testng.annotations.AfterTest;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;

public class LinkTest {
    private static final Pattern COMMA = Pattern.compile(",");

    private WebDriver driver;
    private Wait<WebDriver> wait;

    @DataProvider(name = "links")
    public Object[][] getLinks() throws IOException {
        List<String> lines = FileUtils.readLines(new File("links.csv"));
        Object[][] csvData = new Object[lines.size()][3];

        for (int i = 0; i < lines.size(); i++) {
            csvData[i] = COMMA.split(lines.get(i));
        }
        return csvData;
    }

    @BeforeTest
    public void setUp() throws Exception {
        driver = new FirefoxDriver();
        driver.manage().timeouts().implicitlyWait(5, TimeUnit.SECONDS);
        wait = new WebDriverWait(driver, 10);
    }

    @AfterTest
    public void tearDown() throws Exception {
        driver.quit();
    }

    @Test(dataProvider = "links")
    public void verifyLinks(String url, String link, String title) {
        driver.get(url);
        driver.findElement(By.partialLinkText(link)).click();
        wait.until(ExpectedConditions.titleIs(title));
        assertEquals(title, driver.getTitle());
    }

}

The full project can be found on github.

Jason Gowan