Automatic Logging using Aspects

What is AspectJ? #

AspectJ is a seamless aspect-oriented extension to the Java programming language that enables clean modularization of crosscutting concerns, such as error checking and handling, synchronization, context-sensitive behavior, performance optimizations, monitoring and logging, debugging support, and multi-object protocols.

How can we use AspectJ for automatic logging? #

We can use AspectJ for automatically logging whenever we are performing assertions using org.testng.Assert(stops further execution of the test on failure) or org.testng.asserts.SoftAssert(continues test execution, irrespective of whether the assertions are passing or failing. At the completion of the test execution, TestNG will show all the occurred failures, if any).

This strategy can be applied to various other operations as well.

To know more about AspectJ, please follow the link.

Dependency #

Apart from adding the dependency, we need to attach the dependency to javaagent also.

Maven #

<properties>
   <aspectj.version>1.9.5</aspectj.version>
</properties>


<dependency>
    <groupId>org.aspectj</groupId>
    <artifactId>aspectjweaver</artifactId>
    <version>${aspectj.version}</version>
</dependency>

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-surefire-plugin</artifactId>
            <version>2.22.2</version>
            <configuration>
                <testFailureIgnore>false</testFailureIgnore>
                <argLine>
                    -javaagent:"${settings.localRepository}/org/aspectj/aspectjweaver/${aspectj.version}/aspectjweaver-${aspectj.version}.jar"
                </argLine>
            </configuration>
            <dependencies>
                <dependency>
                    <groupId>org.aspectj</groupId>
                    <artifactId>aspectjweaver</artifactId>
                    <version>${aspectj.version}</version>
                </dependency>
            </dependencies>
        </plugin>
    </plugins>
</build>

Gradle #

configurations {
    agent
}

dependencies {
    agent group: 'org.aspectj', name: 'aspectjweaver', version: '1.9.5'

}

test.doFirst {
    jvmArgs "-javaagent:${configurations.agent.singleFile}"
}

Creating @Aspect #

If we don’t use AspectJ, we may have to explicitly log all the assertions and their arguments for debugging.

The below LoggerAspect class shows how to automatically log all the assertions along with their arguments using AspectJ.

You can think of AspectJ as an interceptor to help log certain methods (as given in the @Pointcut expression) automatically.

package com.example;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;

@Aspect
public class LoggerAspect {

	private static final Logger LOG = LoggerFactory.getLogger(LoggerAspect.class);

	@Pointcut("execution(* org.testng.Assert.assert*(..))")
	public void assertMethod() {
	}

	@Pointcut("execution(* org.testng.asserts.SoftAssert.assert*(..))")
	public void softAssertMethod() {
	}

	@Around("assertMethod() || softAssertMethod()")
	public Object logAsserts(final ProceedingJoinPoint joinPoint) throws Throwable {
		final MethodSignature methodSignature = (MethodSignature) joinPoint.getSignature();
		LOG.debug("assertions ::: calling {} with arguments {}", methodSignature.getMethod().getName(),
				java.util.Arrays.deepToString(joinPoint.getArgs()));
		return joinPoint.proceed();
	}
}

Creating aop-ajc.xml #

aop-ajc.xml is the configuration file that contains all the @Aspect classes to be used by the AspectJ library. Make sure aop-ajc.xml is present under src/main/resources/META-INF path.

<aspectj>
	<aspects>
		<aspect name="com.example.LoggerAspect" />
	</aspects>
</aspectj>

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Now you are familiar with logging to console and file using Logback and automatically logging using AspectJ. In the next section, you’ll learn about reporting.