The basic pattern of unit testing with Neo4j is illustrated by the following example.

To access the Neo4j testing facilities you should have the neo4j-kernel tests.jar on the classpath during tests. You can download it from Maven Central: org.neo4j:neo4j-kernel.

Using Maven as a dependency manager you would typically add this dependency together with JUnit and Hamcrest like so:

Maven dependency.

<project>
...
 <dependencies>
 <dependency>
 <groupId>org.neo4j</groupId>
 <artifactId>neo4j-kernel</artifactId>
 <version>1.9</version>
 <type>test-jar</type>
 <scope>test</scope>
 </dependency>
 <dependency>
 <groupId>junit</groupId>
 <artifactId>junit-dep</artifactId>
 <version>4.11</version>
 <scope>test</scope>
 </dependency>
 <dependency>
 <groupId>org.hamcrest</groupId>
 <artifactId>hamcrest-all</artifactId>
 <version>1.3</version>
 <scope>test</scope>
 </dependency>
 ...
 </dependencies>
...
</project>

Observe that the <type>test-jar</type> is crucial. Without it you would get the common neo4j-kernel jar, not the one containing the testing facilities.

With that in place, we’re ready to code our tests.

Before each test, create a fresh database:

@Before
public void prepareTestDatabase()
{
 graphDb = new TestGraphDatabaseFactory().newImpermanentDatabase();
}

After the test has executed, the database should be shut down:

@After
public void destroyTestDatabase()
{
 graphDb.shutdown();
}

During a test, create nodes and check to see that they are there, while enclosing write operations in a transaction.

Transaction tx = graphDb.beginTx();
Node n = null;
try
{
 n = graphDb.createNode();
 n.setProperty( "name", "Nancy" );
 tx.success();
}
catch ( Exception e )
{
 tx.failure();
}
finally
{
 tx.finish();
}
// The node should have an id greater than 0, which is the id of the
// reference node.
assertThat( n.getId(), is( greaterThan( 0L ) ) );
// Retrieve a node by using the id of the created node. The id's and
// property should match.
Node foundNode = graphDb.getNodeById( n.getId() );
assertThat( foundNode.getId(), is( n.getId() ) );
assertThat( (String) foundNode.getProperty( "name" ), is( "Nancy" ) );

If you want to set configuration parameters at database creation, it’s done like this:

Map<String, String> config = new HashMap<String, String>();
config.put( "neostore.nodestore.db.mapped_memory", "10M" );
config.put( "string_block_size", "60" );
config.put( "array_block_size", "300" );
GraphDatabaseService db = new TestGraphDatabaseFactory()
 .newImpermanentDatabaseBuilder()
 .setConfig( config )
 .newGraphDatabase();