Varying animation behavior

Our lines and turtle are now animating nicely. However, we still need to handle the second type of draw command: rotations. The turtle will move at a constant speed when rotating to a new angle. A full rotation should take 1 second to complete, and we can use this to calculate the duration of the rotation. For example, a quarter rotation will take 0.25 seconds to complete.

In the last section, we started with a test to check that we were calling requestAnimationFrame. This time, that test isn’t essential because we’ve already proved the same design with drawing lines. We can jump right into the more complex tests, using the same triggerRequestAnimationFrame helper as before.

Let’s update Drawing to animate the turtle’s coordinates:

1. Add the following test to the bottom of the Drawing describe block. Create it in another nested describe block, just below the last test you wrote. The test follows the same principle as...