Test stub

Imagine you have a toy kitchen set and you want to make sure your toy oven can cook your toy food properly. You have a friend who is an expert in cooking toy food and you want to ask her to test your toy oven. However, your friend lives far away and can't visit you to test your toy oven directly.

So instead, you decide to send her a picture of your toy oven and ask her to imagine what would happen if she cooked toy food in it. Your friend could use her imagination to figure out if the toy oven would cook the toy food correctly, even without actually using it.

In software development, a test stub is like that picture you sent your toy food expert friend. It's a small piece of code that acts like a stand-in for something else that you don't have access to, like a database or a network connection. A test stub is used when you want to test your software but you don't want to rely on other parts of your software that might not be ready yet, or you don't want to mess up any real data that might be stored somewhere else.

Just like how your friend used her imagination to test your toy oven, a test stub can imagine what would happen if it interacted with parts of your software that aren't available yet. This helps you test your software without having to rely on other parts that might not work correctly or be ready yet.