break out default ranges

src/layercake.js

@@ -7,6 +7,7 @@ import Canvas from './layouts/Canvas.html';
 import Webgl from './layouts/Webgl.html';
 
 import defaultScales from './settings/defaultScales.js';
+import getDefaultRange from './settings/getDefaultRange.js';
 import calcExtents from './lib/calcExtents.js';
 import getActiveKeys from './utils/getActiveKeys.js';
 import partialDomain from './utils/partialDomain.js';
@@ -192,13 +193,11 @@ export default class LayerCakeStore extends Store {
 					if (domains === null) {
 						return null;
 					}
-					// TODO, DRYer and more explicit version of what ranges are defined as, including fallbacks
-					const defaultRanges = {
-						x: settings.reverseX ? [width, 0] : typeof settings.xRange === 'function' ? settings.xRange({ width, height }) : [0, width],
-						y: settings.reverseY ? [height, 0] : typeof settings.yRange === 'function' ? settings.yRange({ width, height }) : [0, height],
-						r: !settings.rRange ? [1, 25] : typeof settings.rRange === 'function' ? settings.rRange({ width, height }) : settings.rRange
-					};
+
+					const defaultRanges = getDefaultRange(s, settings, width, height);
+
 					const scale = settings[thisScale] ? settings[thisScale].copy() : defaultScales[s]();
+
 					scale
 						.domain(partialDomain(domains[s], thisDoughmain)) // on creation, `thisDoughmain` will already have any nulls filled in but if we set it via the store it might not, so rerun it through partialDomain
 						.range(defaultRanges[s]);

src/settings/getDefaultRange.js

@@ -0,0 +1,9 @@
+const getRange = {
+	x: (settings, width, height) => settings.reverseX ? [width, 0] : typeof settings.xRange === 'function' ? settings.xRange({ width, height }) : (settings.xRange || [0, width]),
+	y: (settings, width, height) => settings.reverseY ? [height, 0] : typeof settings.yRange === 'function' ? settings.yRange({ width, height }) : (settings.yRange || [0, height]),
+	r: (settings, width, height) => !settings.rRange ? [1, 25] : typeof settings.rRange === 'function' ? settings.rRange({ width, height }) : settings.rRange
+};
+
+export default function getDefaultRange (s, settings, width, height) {
+	return getRange[s](settings, width, height);
+}

test/getDefaultRange.js

@@ -0,0 +1,45 @@
+/* globals describe it */
+import getDefaultRange from '../src/settings/getDefaultRange.js';
+import * as assert from 'assert';
+
+const name = 'getDefaultRange';
+
+const width = 900;
+const height = 500;
+
+const tests = [
+	/* --------------------------------------------
+	 * Defaults
+	 */
+	{ args: ['x', { }, width, height], expected: [0, width] },
+	{ args: ['y', { }, width, height], expected: [0, height] },
+	{ args: ['r', { }, width, height], expected: [1, 25] },
+	/* --------------------------------------------
+	 * Reverse it
+	 */
+	{ args: ['x', { reverseX: true }, width, height], expected: [width, 0] },
+	{ args: ['y', { reverseY: true }, width, height], expected: [height, 0] },
+	/* --------------------------------------------
+	 * Set a manual default
+	 */
+	{ args: ['x', { xRange: [-100, 100] }, width, height], expected: [-100, 100] },
+	{ args: ['y', { yRange: [-100, 100] }, width, height], expected: [-100, 100] },
+	{ args: ['r', { rRange: [-100, 100] }, width, height], expected: [-100, 100] },
+	/* --------------------------------------------
+	 * Functions!
+	 */
+	{ args: ['x', { xRange: ({ width, height }) => [0, width / 2] }, width, height], expected: [0, width / 2] },
+	{ args: ['y', { yRange: ({ width, height }) => [0, height / 2] }, width, height], expected: [0, height / 2] },
+	{ args: ['r', { rRange: ({ width, height }) => [width / 2, height / 2] }, width, height], expected: [width / 2, height / 2] }
+];
+
+describe(name, function () {
+	tests.forEach(test => {
+		describe(JSON.stringify(test.args), function () {
+			it(`should equal ${JSON.stringify(test.expected)}`, function () {
+				const actual = getDefaultRange(...test.args);
+				assert.deepStrictEqual(actual, test.expected);
+			});
+		});
+	});
+});