Setting timezone for maven unit tests on Java 8

How do I set the timezone for unit tests in maven surefire on Java 8?

With Java 7 this used to work with systemPropertyVariables like in the following configuration, but with Java 8 the tests just use the system timezone.

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-surefire-plugin</artifactId>
  <configuration>
    <systemPropertyVariables>
      <user.timezone>UTC</user.timezone>
    </systemPropertyVariables>

Why is that, and how do I fix it?

Short answer

Java now reads user.timezone earlier, before surefire sets the properties in systemPropertyVariables. The solution is to set it earlier, using argLine:

<plugin>
  ...
  <configuration>
    <argLine>-Duser.timezone=UTC</argLine>

Long answer

Java initializes the default timezone, taking user.timezone into account the first time it needs it and then caches it in java.util.TimeZone. That now happens already when reading a jar file: ZipFile.getZipEntry now calls ZipUtils.dosToJavaTime which creates a Date instance that initializes the default timezone. This is not a surefire-specific problem. Some call it a bug in JDK7. This program used to print the time in UTC, but now uses the system timezone:

import java.util.*;

class TimeZoneTest {
  public static void main(String[] args) {
    System.setProperty("user.timezone", "UTC");
    System.out.println(new Date());
  }
}

In general, the solution is to specify the timezone on the command line, like java -Duser.timezone=UTC TimeZoneTest, or set it programmatically with TimeZone.setDefault(TimeZone.getTimeZone("UTC"));.

Full'ish example:

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-surefire-plugin</artifactId>
        ... could specify version, other settings if desired ...
        <configuration>
          <argLine>-Duser.timezone=UTC</argLine>
        </configuration>
      </plugin>
    </plugins>
  </build>