Chart.js/test/specs/helpers.color.tests.js

const {color, getHoverColor} = Chart.helpers;

describe('Color helper', function() {
	function isColorInstance(obj) {
		return typeof obj === 'object' && obj.valid;
	}

	it('should return a color when called with a color', function() {
		expect(isColorInstance(color('rgb(1, 2, 3)'))).toBe(true);
	});
});

describe('Background hover color helper', function() {
	it('should return a CanvasPattern when called with a CanvasPattern', function(done) {
		var dots = new Image();
		dots.src = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAA4AAAAOCAMAAAAolt3jAAAAD1BMVEUAAAD///////////////+PQt5oAAAABXRSTlMAHlFhZsfk/BEAAAAqSURBVHgBY2BgZGJmYmSAAUYWEIDzmcBcJhiXGcxlRpPFrhdmMiqgvX0AcGIBEUAo6UAAAAAASUVORK5CYII=';
		dots.onload = function() {
			var chartContext = document.createElement('canvas').getContext('2d');
			var patternCanvas = document.createElement('canvas');
			var patternContext = patternCanvas.getContext('2d');
			var pattern = patternContext.createPattern(dots, 'repeat');
			patternContext.fillStyle = pattern;

			var backgroundColor = getHoverColor(chartContext.createPattern(patternCanvas, 'repeat'));

			expect(backgroundColor instanceof CanvasPattern).toBe(true);

			done();
		};
	});

	it('should return a CanvasGradient when called with a CanvasGradient', function() {
		var context = document.createElement('canvas').getContext('2d');
		var gradient = context.createLinearGradient(0, 1, 2, 3);

		expect(getHoverColor(gradient) instanceof CanvasGradient).toBe(true);
	});

	it('should return a modified version of color when called with a color', function() {
		var originalColorRGB = 'rgb(70, 191, 189)';

		expect(getHoverColor('#46BFBD')).not.toEqual(originalColorRGB);
	});
});