curator-test-rule

Summary

This project provides a JUnit TestRule that manages the startup and shutdown of the underlying ZooKeeperServer. The TestRule also includes a way of getting CuratorFramework instances that automatically connect and disconnect from the underlying ZooKeeperServer based on the scope of rule.

Why didn't we use curator-test

• curator-test provides a TestingServer base class, which presents a problem when a testing class needs to extend two different base classes. Using a JUnit TestRule gives us multiple advantages, including the option to start and stop a test server once per test class (@ClassRule) or test method (@Rule).
• There was a race condition in curator-test where if we didn't specify a port, it would bind 0 to get a free port, then unbind from that port, then try to bind to that port later in the code.
• The underlying ZooKeeperServer timeout cannot be configured since we are locked into the configurations in InstanceSpec
• Because of a blocking cnxnFactory.join() call in ZooKeeperServerMain#runFromConfig, curator-test had to do several hacks like spawning a new thread and synchronizing on the status of the ZooKeeperServer

Installation

Include curator-test-rule as a dependency in your build system

###In Gradle

...
repositories {
    mavenCentral()
}

dependencies {
    compile "com.palantir:curator-test-rule:CURRENT_VERSION"
}
...

###In Maven

  ...
  <dependencies>
    <dependency>
      <groupId>com.palantir</groupId>
      <artifactId>curator-test-rule</artifactId>
      <version>CURRENT_VERSION</version>
      <scope>compile</scope>
    </dependency>
  </dependencies>
  ...

How to use it

public final class LocalZooKeeperRuleExample {

    @Rule                                                  // or @ClassRule
    public ZooKeeperRule rule1 = new LocalZooKeeperRule(); // or SharedZooKeeperRule()

    @Test
    public void testCase() {
        CuratorFramework client = rule1.getClient();
        client.getState();

        // do something
    }
}

There are two subclasses of ZooKeeperRule as of now: LocalZooKeeperRule and SharedZooKeeperRule. LocalZooKeeperRule starts and closes the underlying server based on the scope of the TestRule. SharedZooKeeperRule also does this for serial execution. For concurrent execution (such as by using a ParallelSuite), all SharedZooKeeperRules using the same port will share the same underlying server.

Please read the Javadocs for LocalZooKeeperRule and SharedZooKeeperRule for some caveats regarding these classes.

Javadoc

The javadoc is at http://palantir.github.io/curator-test-rule/javadoc/. It is highly recommended to read the javadoc for some caveats when using curator-test-rule.

License

See LICENSE.txt