Grails Maven build does not compile Test Class

I have a grails project converted to maven project using the below command

grails create-pom

I have my test cases written under my /{Grails_Project_Directory}/test/unit/sample/MyTests.groovy

But my Test class files are not getting generated under target/test-classes/unit

Here's maven plugin dependencies for your reference. Please help

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.19</version>
            </plugin>