Chart.js/test/specs/core.animator.tests.js

describe('Chart.animator', function() {
	it('should fire onProgress for each draw', function(done) {
		let count = 0;
		let drawCount = 0;
		const progress = (animation) => {
			count++;
			expect(animation.numSteps).toEqual(250);
			expect(animation.currentStep <= 250).toBeTrue();
		};
		acquireChart({
			type: 'bar',
			data: {
				datasets: [
					{data: [10, 5, 0, 25, 78, -10]}
				],
				labels: ['tick1', 'tick2', 'tick3', 'tick4', 'tick5', 'tick6']
			},
			options: {
				animation: {
					duration: 250,
					onProgress: progress,
					onComplete: function() {
						expect(count).toEqual(drawCount);
						done();
					}
				}
			},
			plugins: [{
				afterDraw() {
					drawCount++;
				}
			}]
		}, {
			canvas: {
				height: 150,
				width: 250
			},
		});
	});

	it('should not fail when adding no items', function() {
		const chart = {};
		Chart.animator.add(chart, undefined);
		Chart.animator.add(chart, []);
		Chart.animator.start(chart);
		expect(Chart.animator.running(chart)).toBeFalse();
	});
});