Using Listeners

TestNG listeners #

There are several interfaces that allow us to change the behavior of TestNG at runtime:

• IAlterSuiteListener - on implementing this interface, we have method alter to alter the test suite
• IAnnotationTransformer - on implementing this interface, we can alter @Test, @DataProvider, @Factory, @Listener annotations
• IClassListener - on implementing this interface, we can call onBeforeClass and onAfterClass
• IConfigurable - on implementing the interface, run method will be invoked instead of each configuration method found
• IConfigurationListener - on implementing this interface, we can call methods onConfigurationSuccess, onConfigurationFailure, onConfigurationSkip and beforeConfiguration
• IDataProviderListener - method beforeDataProviderExecution and afterDataProviderExecution
• IExecutionListener - onExecutionStart and onExecutionFinish
• IHookable - this method has a method run and on implementing, run method will be called instead of @Test method
• IInvokedMethodListener - on implementing this interface, we have method beforeInvocation, afterInvocation, beforeInvocation, afterInvocation that gets invoked before and after a method is invoked by TestNG, irrespective of whether they pass/fail or gets skipped
• IMethodInterceptor - on implementing the interface, we can call intercept to alter the list of test methods that TestNG is about to run
• IReporter - on implementing the interface, we have method generateReport to create custom reports
• ISuiteListener - on implementing the interface, we can call onStart and onFinish
• ITestListener - on implementing the interface, we have methods onTestStart, onTestSuccess, onTestFailure, onTestSkipped, onTestFailedButWithinSuccessPercentage, onTestFailedWithTimeout, onStart, onFinish

Declaring listeners #

In testng.xml #

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite name="Sample Test Suite" parallel="tests" thread-count="5">
    <listeners>
        <listener class-name="com.example.SampleTestListener" />
    </listeners>
    <test name="Sample Test">
        ...
    </test>
</suite>

Listeners can be configured for the entire test suite in testng.xml like above. Under <listeners>, multiple <listener> can be added.

In TestClass #

@Listeners( { com.example.SampleTestListener.class } )
public class TestClass {
     ....
}

Listeners can be configured only for certain test classes like the above code snippet by adding @Listeners({ ListenerA.class, ListenerB.class, ...}) at the class level.

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That is how listeners work with TestNG. In the next lesson, you will study how to restart a failed test.