running gwt precompile from within your pom

gistfile1.txt

      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>exec-maven-plugin</artifactId>
        <version>1.2.1</version>
        <executions>
          <execution>
            <id>verify-modules</id>
            <phase>test</phase>
            <goals><goal>exec</goal></goals>
            <configuration>
             <executable>java</executable>
             <classpathScope>compile</classpathScope>
              <arguments>
                <argument>-cp</argument>
                <classpath />
                <argument>com.google.gwt.dev.CompileModule</argument>
                <argument>-strict</argument>
                <argument>-out</argument>
                <argument>target/precompile</argument>
                <argument>package.to.some.Module</argument>
                <argument>package.to.another.Module</argument>
                <!-- etc -->
              </arguments>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>