What is a mock object?

In object oriented programming mock objects are simulated objects that mimic the behaviour of real objects in a controlled way. Similar to a crash test dummy in car design.
You might use a mock object when a real object is impracticle or impossible to incorporate in a unit test or to test behaviour which is new.
Mock objects are used in test driven development.

Show what you know and what you don't know

Be generous in sharing your knowledge (without inflicting help). But also be willing to hear other peoples' ideas, build on them, and help others shine. Admit when you don't know the answers; there's nothing worse than a know-it-all who is wrong. Asking for help helps others see you as a real person, and people generally like to behelpful.

Advice from Esther Derby's "Insights you can use" blog
Article: 5 ways that team members build trust with each other (April 02 2009)