When testing parking brakes, what is the initial action required?

When testing parking brakes, the initial action requires you to buckle up and set the brake. This step is essential because safety is paramount during vehicle testing. By buckling up, the driver ensures their safety while performing the test, which may involve movements or adjustments to the vehicle. Setting the parking brake is crucial because the test will assess whether the brake holds the vehicle in place when it is on an incline or during other conditions. This initial action lays the foundation for a proper test of the braking system, ensuring that all safety protocols are followed before any tests are conducted, which is critical for both the tester's safety and the integrity of the test results.