This tutorial focusses on the usage of Metro management APIs within a testcase with the objective of fully simulating formal commissioning and decommissioning of components in a unit testcase.

The following code establishes the runtime context for all testXxx methods in the testcase. In this example we are locating the part definition for the project from the target directory, converting the part location to a URI, and loading the part. In addition, we explicity request a Component instance via the the Part.getContent request.

public void setUp() throws Exception 
{
    m_logger = Logger.getLogger( "test" );
    m_logger.info( "commissioning" );
    URI uri = getPartURI();
    Part part = Part.load( uri );
    m_component = (Component) part.getContent( new Class[]{Component.class} );
}

private URI getPartURI() throws Exception
{
    String path = System.getProperty( "project.deliverable.part.path" );
    File file = new File( path );
    return file.toURI();
}
        

The Component instance exposes a bunch of management operations. One of these is the operation getProvider() which gives us access to the manager of one instance of the class specificed by the component type. The provider exposes the operation getValue( boolean ) which is where we actually get a fully initialized instance (and keep in mind here that full-initialized means that all initialization actions (such as state transitions) have alrady been successfully completed.

public void testExampleComponent() throws Exception 
{
    m_logger.info( "testing" );
    Provider provider = m_component.getProvider();
    ContainerImpl container = (ContainerImpl) provider.getValue( false );
    
    // Any tests assertions go here.
}
        

With debug level logging assigned to the top-level component the following output will be generated:

test:
    [junit] Executing forked test.
    [junit] Running acme.test.ExampleTest
    [junit] [14139] [INFO   ] (test): commissioning
    [junit] [14139] [FINE   ] (container): loaded [acme.ContainerImpl]
    [junit] [14139] [FINE   ] (container): established SINGLETON:HARD lifestyle handler.
    [junit] [14139] [INFO   ] (test): testing
    [junit] [14139] [FINE   ] (container.child): loaded [acme.ChildImpl]
    [junit] [14139] [FINE   ] (container.child): established SINGLETON:HARD lifestyle handler.
    [junit] [14139] [INFO   ] (container): configuration uri: local:properties:acme/examples/services/configuration
    [junit] [14139] [FINE   ] (container.child): instantiated [4744654]
    [junit] [14139] [FINE   ] (container.child): activated [4744654]
    [junit] [14139] [FINE   ] (container): instantiated [21854021]
    [junit] [14139] [INFO   ] (container): starting
    [junit] [14139] [INFO   ] (container.child): starting with: local:properties:acme/examples/services/configuration
    [junit] [14139] [INFO   ] (container): configurable service started successfully
    [junit] [14139] [FINE   ] (container): activated [21854021]
    [junit] [14139] [INFO   ] (test): decommissioning
    [junit] [14139] [INFO   ] (container): stopping
    [junit] [14139] [INFO   ] (container.child): stopping
    [junit] Tests run: 1, Failures: 0, Errors: 0, Time elapsed: 0.859 sec
        

The following code gaurantees that the component instance will be formally decommissioned (in effect simulating the normal decommissioning behaviour you would see if the component was deployed under the DPML Station).

public void tearDown() throws Exception
{
    m_logger.info( "decommissioning" );
    Disposable disposable = (Disposable) m_component;
    disposable.dispose();
}
        

Usage of classes in the net.dpml.component package enables the formal control of a component. In effect your testcase is acting as the component controller and the overall impact of commissioning and decommissioning cycles can be fully assessed.