Overwriting a single bean for test?

[BrandonY]

I have a very large application with a very large application-context.xml file. I have many unit tests, and occasionally I want to write a quick unit test that replaces any particular bean with a mocked out replacement. I see that it's quite possible to create separate application-contexts for testing that can override small pieces of application-context, but is there a way to do this inline from a unit test class file?

In other words, if I have bean Foo, which has bean Baz as a property, which in turn has bean Bar as a property, and I want to replace Bar with mockBar for a single test, how could I do that?

I'd like it to look something like this:

public void testSomething() {
  Bar mockBar = new Mock(Bar.class);
  
  context =
   createNewApplicationContextJustLikeOldOneExceptBarIs(mockBar);

  Foo foo = context.getBean("foo");
}

Can this be done cleanly? How is something like this normally handled?

[nstoddar]

Normally, I'd say that you wouldn't use a mock unless you were doing a simple unit test (aka no Spring application context). If you absolutely had to, I'd guess that your beans just weren't developed very thoughtfully -- use a service locator so your class is more testable.

That being said, I suppose you could write your own FactoryBean that creates a mock for a class, and include a definition in your spring config files so it overrides the original definition.