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Want to learn more about WebDriver? What do you want to know?

So you’ve written your first Selenium 2.0 test, but is that really the right way to build tests? In the second article in this series we’ll look at the difference between test specification and test implementation and how Selenium achieves this with page objects.

Specification vs Implementation

There’s an important difference in tests between the specification of what to test versus the implementation of how to test.

For example, my test specification might be “When the user enters their username and password and clicks the login button, then they are logged in and can see their recommendations”. This describes a scenario – it’s a specification of what the test should do. However, the test implementation has to deal with things like:

  • The username field is named “f_username”
  • The password field is named “f_password”
  • The login button is found via the CSS “#loginButton input”

If I change the layout of my login page, does the specification change? Hell no – I still need to provide credentials and click the login button. But has my implementation changed? Almost certainly!

Separating test specification from test implementation makes tests more robust. If I change how login works, I don’t want to have to change every single test that needs a logged in user – there’s probably a few of them! Instead, I only want to change the implementation – which fields to use, which buttons to press – in a single, common location.

Using Page Objects

In Selenium, you can separate specification from implementation by using page objects. That is, unlike in our previous example where the test code is littered with implementation details (how to find the keyword field or how to find the submit button), instead we move this logic into a page object.

If we built a page object to represent the Amazon home page, what would it look like?

public class AmazonHomePage {
    public static AmazonHomePage navigateTo(WebDriver driver);
    public AmazonSearchResultsPage searchFor(String searchTerm);
}

The homepage has two responsibilities that our test cares about:

  1. Given a browser, navigate to the page
  2. Once on the page, search for a specific search term

Notice that the searchFor operation returns a different type of page object – because after entering the search we will be on a new page: the search results page. What does that page look like?

public class AmazonSearchResultsPage {
    public String getTopResultTitle();
}

We only need one thing from our search results page – the title of the top result.

Tests with Page Objects

The page object encapsulates all the logic about how to perform certain actions. Our test now only needs to deal with what to actually do – so what does our test look like now?

AmazonHomePage homePage = AmazonHomePage.navigateTo(driver);
AmazonSearchResultsPage resultsPage =
    homePage.searchFor("iain banks");
assertThat(resultsPage.getTopResultTitle(), is("Transition"));

This is a pretty neat specification for our test: given a user on the amazon home page, when the user searches for ‘iain banks’, then the title of the top result is ‘Transition’.

There’s no implementation details in our test now. If any of the implementation details around searching change – we only need to change our page object. This is particularly important when the page objects are reused by multiple tests. Instead of having to manually change dozens of tests, we make our change in a single location – the page object.

Implementing Page Objects

By removing the implementation details from the test, they now sit within the page object. So how could we implement the page object interfaces we defined above? We could simply reuse the logic we had in our tests previously:

public AmazonSearchResultsPage searchFor(String searchTerm) {
    // Enter a search term
    WebElement keywordsField =
        driver.findElement(By.name("field-keywords"));
    keywordsField.sendKeys(searchTerm);

    // Click go
    WebElement goButton =
        driver.findElement(By.cssSelector("#navGoButton input"));
    goButton.click();
    ...

However, Selenium gives us another way to do this – we can also define the web elements declaratively, by using annotations. Although either approach is valid, using annotations tends to be neater. So let’s have a look at the top of the homepage class now:

public class AmazonHomePage {

	@FindBy(name="field-keywords")
	private WebElement keywordsField;

	@FindBy(css="#navGoButton input")
	private WebElement goButton;

Here we define the same two WebElements we had in our test before. But rather than call the web driver to find the elements for us explicitly, they’re now pre-populated based on the annotation.

To implement the interface we described above, we simply need to invoke the sendKeys and click methods on these elements as we did previously:

public AmazonSearchResultsPage searchFor(String searchTerm) {
    keywordsField.sendKeys(searchTerm);
    goButton.click();
    return PageFactory.initElements(driver,
        AmazonSearchResultsPage.class);
}

On lines two and three we type in our search term to the field we declared above and then click the go button. But what on earth is happening on lines four and five? This piece of magic – the PageFactory – is what allows us to use annotations to declare our elements.

Page Factory

The page factory instantiates our page object (AmazonSearchResultsPage) and finds the annotated fields. The fields are then initialised to the associated elements on the page. This is how we’re able to simply use the fields without having to initialise them. The returned search results page is then a fully populated page object, ready to be used by the test as before.

There’s one more method to see on the homepage – the navigateTo method. This also uses the page factory – this time to initialise our AmazonHomePage.

	public static AmazonHomePage navigateTo(WebDriver driver) {
		driver.get("http://www.amazon.co.uk/");
		return PageFactory.initElements(driver,
             AmazonHomePage.class);
	}

And there we have it – a better amazon search example – now using page objects and annotations. This is a much better way to structure tests than having implementation and specification intermingled within the test.

As before, all the examples are available on github. This article was part 2 in a series, if there’s a specific aspect of using Selenium you’d like to see covered in a future article let us know in the comments below.

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Want to learn more about WebDriver? What do you want to know?

With the release of Selenium 2.0 the best name in web testing and the best API have come together in a match surely made in heaven. In this, the first article in a series, we’ll look at what it takes to start writing automated browser tests using Selenium 2.0.

What Is It?

Selenium is a browser-based testing tool. With it you can write tests that drive the browser – clicking on links, filling in forms – just like your users do; so you can test your application works correctly when used the way your users do. If you’re not doing browser-based end-to-end testing, how do you know your application works when your users actually use it?

What Do I Do?

  1. Download selenium or configure a maven dependency
  2. Write one or more tests
  3. Run them as part of your continuous integration
  4. Profit!

I’ll assume you know how to do (1) so we’ll start with (2) in this article. If you’re interested in (3), why not subscribe because we’ll cover that in future. (4) is an advanced topic and is left as an exercise for the reader.

All the examples below are on github – including an example maven pom if you’re so inclined.

Should I Use Selenium IDE?

NO. Unfortunately Selenium IDE isolates you from the mechanics of how your test is implemented. While this sounds like a good thing, it tends to lead to hard-to-maintain tests and a world of hurt. Instead, write your tests using your favourite testing framework – I’m working in Java, so the tests I’ll show below are JUnit tests.

My First Test

Let’s start with a really simple test, we’ll search Amazon for one of my favourite authors.

First, we need a driver – this is what actually interacts with a running browser – we’ll use the Firefox driver, you could instead use Chrome or Internet Explorer, if that’s what floats your boat.

FirefoxDriver driver = new FirefoxDriver();

This fires up a browser, ready to be controlled. Next we need to visit a page – so let’s go to the Amazon homepage.

driver.get("http://www.amazon.co.uk/");

Now we’re on the Amazon homepage, let’s enter in a search term.

WebElement keywordsField =
    driver.findElement(By.name("field-keywords"));
keywordsField.sendKeys("iain banks");

Wait a minute – what happened there? The first two lines tell the driver to find an element on the page. We’re identifying it by name, e.g. this would find something that looks like:

<input name="field-keywords" ... />

Once we’ve found that element on the page – we send it some keys. This simulates us typing in the search term into the relevant field.

But that’s not quite enough, we also need to execute the search. So let’s click the search button:

WebElement goButton =
    driver.findElement(By.cssSelector("#navGoButton input"));
goButton.click();

As before, we find an element – but this time we use a CSS selector. As the name suggests, this finds elements exactly the same way CSS selectors do. So this finds something that looks like:

    <div id="navGoButton">
        ...
          <input type="..." />
    </div>

Once we’ve found the element, we click on it – this loads the results page. Note: the call to click() will block until the page has finished loading, so whatever we do next will only happen once the page has loaded.

What do we do next? Let’s check that the top result is the book we expect it to be:

WebElement topResultTitle =
    driver.findElement(By.cssSelector("#result_0 .title a"));
assertThat(topResultTitle.getText(), is("Transition"));

Again we identify an element using a CSS selector, but this time we get the text of the element. This finds the relevant link and returns the text it contains – in this case, the title of the book.

If you run this test, you’ll see (racing by): the amazon home page open, the search term entered and the results page loaded.

Congratulations! We wrote our first Selenium test. Now let’s move on to part two: using page objects.

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On a pet project recently I set out to build automated UI (integration) tests as well as the normal unit tests. I wanted to get all of this integrated into my maven build, with code coverage reports so I could get an idea of areas with insufficient test coverage. Rather than just publish the source code for the project, I’ve put together a simple example to demonstrate how I got all this setup; so if you’re looking to integrate maven, junit, webdriver (now selenium) and emma - read on to find out how I went about it.

First off, all the source code for this is available on github: https://github.com/activelylazy/coverage-example. I’ll show key snippets, but obviously there’s lots of detail omitted that (hopefully) isn’t relevant.

The Example App

Rather than break with tradition, the example application is a simple, if slightly contrived, hello world:

How It Works

The start page is a simple link to the hello world page:

<h1>Example app</h1>
<p>See the <a id="messageLink" href="helloWorld.html">message</a></p>

The hello world page just displays the message:

<h1>Example app</h1>
<p id="message"><c:out value="${message}"/></p>

The hello world controller renders the view, passing in the message:

public class HelloWorldController extends ParameterizableViewController {
    // Our message factory
    private MessageFactory messageFactory;
    @Override
    protected ModelAndView handleRequestInternal(HttpServletRequest request,
        HttpServletResponse response) throws Exception {
        // Get the success view
        ModelAndView mav = super.handleRequestInternal(request, response);
        // Add our message
        mav.addObject("message",messageFactory.createMessage());
        return mav;
    }
    @Autowired
    public void setMessageFactory(MessageFactory messageFactory) {
        this.messageFactory = messageFactory;
    }
}

Finally the MessageFactory simply returns the hard-coded message:

public String createMessage() {
    return "Hello world";
}

The unit test

We define a simple unit test to verify that the MessageFactory behaves as expected:

public class MessageFactoryTest {
    // The message factory
    private MessageFactory messageFactory;
    @Test
    public void testCreateMessage() {
        assertEquals("Hello world",messageFactory.createMessage());
    }
    @Autowired
    public void setMessageFactory(MessageFactory messageFactory) {
        this.messageFactory = messageFactory;
    }
}

Build

A basic maven pom file is sufficient to build this and run the unit test. At this point we have a working app, with a unit test for the core functionality (such as it is) that we can build and run.

<project>
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>helloworld</artifactId>
    <packaging>war</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>helloworld Maven Webapp</name>
    <build>
        <finalName>helloworld</finalName>
    </build>
    <dependencies>
        ...omitted...
    </dependencies>
</project>

Code Coverage

Now let’s integrate Emma so we can get some code coverage reports. First, we define a new Maven profile, this allows us to control whether or not we use emma on any given build.

<profile>
    <id>with-emma</id>
    <build>
        <plugins>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>emma-maven-plugin</artifactId>
                <inherited>true</inherited>
                <executions>
                    <execution>
                        <id>instrument</id>
                        <phase>process-test-classes</phase>
                        <goals>
                            <goal>instrument</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</profile>

This simply invokes the “instrument” goal during the Maven “process-test-classes” phase; i.e. once we’ve compiled our class files, use emma to instrument them. We can run this by invoking maven with the new profile:

mvn clean install -Pwith-emma

Once the build has completed, we can run Emma to generate code coverage reports:

On Windows:

java -cp %USERPROFILE%/.m2/repository/emma/emma/2.0.5312/emma-2.0.5312.jar emma report -r xml,html -in coverage.ec -in target/coverage.em

On Linux:

java -cp ~/.m2/repository/emma/emma/2.0.5312/emma-2.0.5312.jar emma report -r xml,html -in coverage.ec -in target/coverage.em

We can now view the HTML coverage report in coverage/index.html. At this point, it shows we have 50% test coverage (by classes). MessageFactory is fully covered, but the HelloWorldController doesn’t have any tests at all.

Integration Test

To test our controller and JSP, we’ll use WebDriver to create a simple integration test; this is a JUnit test that happens to launch a browser.

public class HelloWorldIntegrationTest {
    // The webdriver
    private static WebDriver driver;
    @BeforeClass
    public static void initWebDriver() {
        driver = new FirefoxDriver();
    }
    @AfterClass
    public static void stopSeleniumClent() {
        try {
            driver.close();
            driver.quit();
        } catch( Throwable t ) {
            // Catch error & log, not critical for tests
            System.err.println("Error stopping driver: "+t.getMessage());
            t.printStackTrace(System.err);
        }
    }
    @Test
    public void testHelloWorld() {
        // Start from the homepage
        driver.get("http://localhost:9080/helloworld/");
        HomePage homePage = new HomePage(driver);
        HelloWorldPage helloWorldPage = homePage.clickMessageLink();
        assertEquals("Hello world",helloWorldPage.getMessage());
    }
}

Lines 4-18 simply start Web Driver before the test and shut it down (closing the browser window) once the test is finished.

On line 22 we navigate to the homepage with a hard-coded URL.

On line 23 we initialise our Web Driver page object for the homepage. This encapsulates all the details of how the page works, allowing the test to interact with the page functionally, without worrying about the mechanics (which elements to use etc).

On line 24 we use the homepage object to click the “message” link; this navigates to the hello world page.

On line 25 we confirm that the message shown on the hello world page is what we expect.

Note: I’m using page objects to separate test specification (what to do) from test implementation (how to do it). For more on why this is important see keeping tests from being brittle.

Homepage

The homepage object is pretty simple:

public HelloWorldPage clickMessageLink() {
    driver.findElement(By.id("messageLink")).click();
    return new HelloWorldPage(driver);
}

HelloWorldPage

The hello world page is equally simple:

public String getMessage() {
    return driver.findElement(By.id("message")).getText();
}

Running the Integration Test

To run the integration test during our Maven build we need to make a few changes. First, we need to exclude integration tests from the unit test phase:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    ...
    <configuration>
        ...
        <excludes>
            <exclude>**/*IntegrationTest.java</exclude>
            <exclude>**/common/*</exclude>
        </excludes>
    </configuration>
</plugin>

Then we define a new profile, so we can optionally run integration tests:

<profile>
    <id>with-integration-tests</id>
    <build>
        <plugins>
            <plugin>
                <groupId>org.mortbay.jetty</groupId>
                <artifactId>maven-jetty-plugin</artifactId>
                <version>6.1.22</version>
                <configuration>
                    <scanIntervalSeconds>5</scanIntervalSeconds>
                    <stopPort>9966</stopPort>
                    <stopKey>foo</stopKey>
                    <connectors>
                        <connector implementation="org.mortbay.jetty.nio.SelectChannelConnector">
                            <port>9080</port>
                            <maxIdleTime>60000</maxIdleTime>
                        </connector>
                    </connectors>
                </configuration>
                <executions>
                    <execution>
                        <id>start-jetty</id>
                        <phase>pre-integration-test</phase>
                        <goals>
                            <goal>run</goal>
                        </goals>
                        <configuration>
                            <daemon>true</daemon>
                        </configuration>
                    </execution>
                    <execution>
                        <id>stop-jetty</id>
                        <phase>post-integration-test</phase>
                        <goals>
                            <goal>stop</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.5</version>
                <inherited>true</inherited>
                <executions>
                    <execution>
                        <id>integration-tests</id>
                        <phase>integration-test</phase>
                        <goals>
                            <goal>test</goal>
                        </goals>
                        <configuration>
                            <excludes>
                                <exclude>**/common/*</exclude>
                            </excludes>
                            <includes>
                                <include>**/*IntegrationTest.java</include>
                            </includes>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</profile>
<profile>
<id>with-integration-tests</id>
<build>
<plugins>
<plugin>
<groupId>org.mortbay.jetty</groupId>
<artifactId>maven-jetty-plugin</artifactId>
<version>6.1.22</version>
<configuration>
<scanIntervalSeconds>5</scanIntervalSeconds>
<stopPort>9966</stopPort>
<stopKey>foo</stopKey>
<connectors>
<connector implementation=”org.mortbay.jetty.nio.SelectChannelConnector”>
<port>${test.server.port}</port>
<maxIdleTime>60000</maxIdleTime>
</connector>
</connectors>
</configuration>
<executions>
<execution>
<id>start-jetty</id>
<phase>pre-integration-test</phase>
<goals>
<goal>run</goal>
</goals>
<configuration>
<daemon>true</daemon>
</configuration>
</execution>
<execution>
<id>stop-jetty</id>
<phase>post-integration-test</phase>
<goals>
<goal>stop</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.5</version>
<inherited>true</inherited>
<executions>
<execution>
<id>integration-tests</id>
<phase>integration-test</phase>
<goals>
<goal>test</goal>
</goals>
<configuration>
<excludes>
<exclude>**/common/*</exclude>
</excludes>
<includes>
<include>**/*IntegrationTest.java</include>
</includes>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</profile>

This may look complex, but really we’re just configuring jetty to run while we run our integration tests; then configuring how to run the integration tests themselves.

In lines 9-19 configure jetty – the port to run on and how to stop it.

Lines 21-30 configure jetty to run during the “pre-integration-test” phase of the maven build.

Lines 31-37 configure jetty to be stopped during the “post-integration-test” phase of the maven build.

In lines 40-62 we use the maven-surefire-plugin again, this time to run during the “integration-test” phase of the build, only running our integration test classes.

We can run this build with:

mvn clean install -Pwith-emma -Pwith-integration-tests

This will build everything, run the unit tests, build the war, fire up jetty to host the war, run our integration tests (you’ll see a firefox window popup while the rest runs) then shut down jetty. Because the war is built with instrumented classes, Emma also tracks code coverage while we run our integration tests.

We can now build our application, running unit tests and integration tests, gathering combined code coverage reports. If we re-run the emma report and check code coverage we now see we have 100% test coverage – since the controller is also being covered through tests.

Issues

What are the outstanding issues with this, what further extensions can be made?

  • The build produces an instrumented WAR – this means you need to run a second build, without emma, to get a production-ready build.
  • The integration test hard-codes the port that Jetty is configured to start on; meaning the tests can’t be run directly within Eclipse. It is possible to pass this port in, defaulting to say, 8080, so that integration tests can be run seemlessly within Eclipse as well via the maven build
  • When running on your build server you probably don’t want Firefox popping up at random (if X is even installed); so running xvfb is a good idea. It is possible to setup maven to start & stop xvfb before & after the integration tests.

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