This way of implementing a MockObject in java allows any java construct to
be used to test or prepare data within the MockObject method invocation.

The test sets up a list of expected calls. Each expected call defines an
invocation handler (implemented by an anonymous inner class). The invocation
handler must provide a method with the same name and parameters as that in
the MockObject. The framework uses the Java1.3 Proxy class to automatically
delegate the MockObject method invocation to the expected call invocation handler.

e.g. Suppose we have this useful helper class that we would like to test:

 public class R''''''equestWrapper {
	public R''''''equestWrapper( H''''''ttpServletRequest request ) {
	 this.request = request;
	}
	
	public String getName() {
	 return getFirstName() + " " + getLastName();
	}
	
	private String getFirstName() {
	 return this.request.getParameter("firstname");
	}
	
	private String getLastName() {
	 return this.request.getParameter("lastname");
	}
	
	private final H''''''ttpServletRequest request;
 }

We need to mock the H''''''ttpServletRequest. The test case looks like this:

 public class R''''''equestWrapperTest extends TestCase{
	
	public R''''''equestWrapperTest(String name) {
	super(name);
	}
	
	public static Test suite() {
	return new TestSuite(R''''''equestWrapperTest.class);
	}
	
	public static void main( String[] args) {
	TestRunner.run(R''''''equestWrapperTest.class);
	}
	
	public void test() throws Exception {
	// defines the order of calls
	M''''''ockCallQueue mockCallQueue = new M''''''ockCallQueue();
	H''''''ttpServletRequest mockRequest = (H''''''ttpServletRequest)mockCallQueue.newMockObject( H''''''ttpServletRequest.class );
	mockCallQueue.addExpectedCall( mockRequest, new L''''''ocalMockInvocationHandler() {
		public String getParameter( String name ) {
		assertEquals( "firstname", name );
		return "Joe";
		}
	});
	mockCallQueue.addExpectedCall( mockRequest, new L''''''ocalMockInvocationHandler() {
		public String getParameter( String name ) {
		assertEquals( "lastname", name );
		return "Bloggs";
		}
	});
	R''''''equestWrapper objectUnderTest = new R''''''equestWrapper( mockRequest );
	assertEquals( "Joe Bloggs", objectUnderTest.getName() );
	mockCallQueue.assertAllCallsInvoked();
	}

	private static abstract class L''''''ocalMockInvocationHandler extends M''''''ockInvocationHandler{
	protected Object invoke( Method methodOnThis, Object[] arguments) throws I''''''nvocationTargetException, Il''''''legalAccessException{
		return methodOnThis.invoke( this, arguments );
	}
	}
 }

Annoyingly, it is necessary to have the L''''''ocalMockInvocationHandler inner
class. This can be copied verbatim into any test case. The problem is that
even public methods in anonymous inner classes are not accessible outside
of the enclosing class. We can get a Method object but we can't invoke it.
The invoke method of L''''''ocalMockInvocationHandler means that the actual
method.invoke() is performed within a context that can access the methods
of the invocation handler.

The whole example and framework can be found in
http://www.neil.swingler.name/amock.jar

-- NeilSwingler

For simple mocks, EasyMock is nice.

-- TammoFreese

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[CategoryMockObjects]