Java + Groovy + TestNG + Maven combination example3 (replace singleton field)

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>gjt3</groupId>
  <artifactId>gjt3</artifactId>
  <packaging>jar</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>gjt3</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>org.codehaus.groovy</groupId>
      <artifactId>groovy-all</artifactId>
      <version>1.8.8</version>
    </dependency>
    <dependency>
      <groupId>org.testng</groupId>
      <artifactId>testng</artifactId>
      <version>[6.8,)</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
  <build>
    <plugins>
      <plugin>
        <groupId>org.codehaus.gmaven</groupId>
        <artifactId>gmaven-plugin</artifactId>
        <version>1.4</version>
        <configuration>
          <providerSelection>1.8</providerSelection>
        </configuration>
        <executions>
          <execution>
            <goals>
              <goal>generateStubs</goal>
              <goal>compile</goal>
              <goal>generateTestStubs</goal>
              <goal>testCompile</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

Singleton.java

package gjt3;

public class Singleton {
    private static Singleton instance = null;
    private String myarg;
    private Singleton(String arg) {
        myarg = arg;
    }
    public synchronized static Singleton getInstance(String arg) {
        if (Singleton.instance == null) {
            Singleton.instance = new Singleton(arg);
        }
        return Singleton.instance;
    }
    public String getArg() {
        return myarg;
    }
}

SingletonTest.groovy

package gjt3;

import org.testng.Assert;
import org.testng.annotations.Test;

public class SingletonTest {
    @Test
    public void ignoreSingleton() {
        Singleton s1 = Singleton.getInstance("s1");
        Assert.assertEquals(s1.getArg(), "s1");

        Singleton s2 = Singleton.getInstance("s2");
        Assert.assertEquals(s2.getArg(), "s1");

        Singleton s3 = new Singleton("s3");
        Assert.assertEquals(s3.getArg(), "s3");
        Singleton.instance = s3;

        Singleton s4 = Singleton.getInstance("s4");
        Assert.assertEquals(s4.getArg(), "s3");
    }
}