mouse-movement.function.spec.ts

import {
    calculateStepDuration,
    linear,
    calculateMovementTimesteps, EasingFunction
} from "./mouse-movement.function";

describe("MovementType", () => {
    describe("baseStepDuration", () => {
        it("should calculate the base step duration in nanoseconds", () => {
            // GIVEN
            const speedInPixelsPerSecond = 1000;
            const expectedBaseStepDuration = 1_000_000;

            // WHEN
            const result = calculateStepDuration(speedInPixelsPerSecond);

            // THEN
            expect(result).toBe(expectedBaseStepDuration);
        });
    });

    describe("stepDuration", () => {
        it("should call easing function progress to calculate current step duration", () => {
            // GIVEN
            const amountOfSteps = 100;
            const speedInPixelsPerSecond = 1000;
            const easingFunction = jest.fn(() => 0);

            // WHEN
            calculateMovementTimesteps(amountOfSteps, speedInPixelsPerSecond, easingFunction);

            // THEN
            expect(easingFunction).toBeCalledTimes(amountOfSteps);
        })
    });

    describe('linear', () => {
        it("should return a set of linear timesteps, 1000000 nanosecond per step.", () => {
            // GIVEN
            const expected = [1000000, 1000000, 1000000, 1000000, 1000000, 1000000];

            // WHEN
            const result = calculateMovementTimesteps(6, 1000, linear);

            // THEN
            expect(result).toEqual(expected);
        });

        it("should should return a set of linear timesteps, 2000000 nanoseconds per step.", () => {
            // GIVEN
            const expected = [2000000, 2000000, 2000000, 2000000, 2000000, 2000000];

            // WHEN
            const result = calculateMovementTimesteps(6, 500, linear);

            // THEN
            expect(result).toEqual(expected);
        });
    });

    describe('non-linear', () => {
        it("should return progress slowly in the first half, 2000000 nanoseconds per step, then continue with normal speed, 1000000 nanoseconds per step", () => {
            // GIVEN
            const mouseSpeed = 1000;
            const easingFunction: EasingFunction = (p: number) => {
                if (p < 0.5) {
                    return -0.5;
                }
                return 0;
            };
            const expected = [2000000, 2000000, 2000000, 1000000, 1000000, 1000000];

            // WHEN
            const result = calculateMovementTimesteps(6, mouseSpeed, easingFunction);

            // THEN
            expect(result).toEqual(expected);
        });
    });
});