A more thorough explanation:

Definition: The infringement test is a method used in patents to determine if a dependent claim is valid. It involves asking whether the dependent claim would always be infringed if the independent claim on which it is based were infringed. Since a dependent claim must include all the elements of the independent claim, an infringement of the independent claim must also be an infringement of the dependent claim.

Example: Let's say a company has a patent for a new type of phone case. The independent claim might be for a case that is made of a specific material and has a certain shape. A dependent claim might be for a case that has the same material and shape, but also includes a built-in screen protector. To determine if the dependent claim is valid, the infringement test would be used. If someone were to infringe on the independent claim by making a phone case with the same material and shape, they would also be infringing on the dependent claim because it includes those same elements plus an additional feature.

Explanation: The example illustrates how the infringement test works by showing how a dependent claim is based on an independent claim and must include all of its elements. If someone were to infringe on the independent claim, they would also be infringing on the dependent claim because it includes those same elements plus an additional feature. This shows how the infringement test is used to determine if a dependent claim is valid and can be enforced under the patent.