App.java

package com.keyholesoftware.blog;

public class App
{
    public static void main( String[] args )
    {
        System.out.println( "Hello World!" );
    }
}

AppTest.java

package com.keyholesoftware.blog;

import junit.framework.*;

public class AppTest extends TestCase
{
    public void testApp()
    {
        assertTrue( true );
    }
}

Dockerfile

FROM maven:3.2.5-jdk-8u40

RUN mkdir --parents /usr/src/app
WORKDIR /usr/src/app

ADD . /usr/src/app
RUN mvn verify

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/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.keyholesoftware.blog</groupId>
  <artifactId>khs-docker-caching-blog</artifactId>
  <version>1.0-SNAPSHOT</version>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
</project>