feat(colors): improve colors config

src/ColorUtils.js

@@ -7,15 +7,15 @@ export const getColorGenerator = instruction => {
     }
 
     if (instruction === 'inherit') {
-        return d => d.data.color;
+        return d => (d.color || d.data.color);
     }
 
     const inheritMatches = instruction.match(/inherit:(darker|brighter)\(([0-9.]+)\)/);
     if (inheritMatches) {
         const method = inheritMatches[1];
         const amount = inheritMatches[2];
 
-        return d => d3.rgb(d.data.color)[method](parseFloat(amount));
+        return d => d3.rgb(d.color || d.data.color)[method](parseFloat(amount));
     }
 
     throw new Error('Unable to determine color generator');

test/ColorUtils.test.js

@@ -0,0 +1,54 @@
+import test                  from 'ava';
+import d3                    from 'd3';
+import { getColorGenerator } from '../src/ColorUtils';
+
+
+test(`getColorGenerator() should return 'none' if 'none' provided`, t => {
+    t.is(getColorGenerator('none'), 'none');
+});
+
+test(`getColorGenerator() should return a function to use 'data.color' if 'inherit' provided`, t => {
+    const colorGenerator = getColorGenerator('inherit');
+    const color          = '#FF0000';
+
+    t.is(typeof colorGenerator, 'function');
+    t.is(colorGenerator({ data: { color }}), color);
+});
+
+test(`getColorGenerator() should return a function to use darker 'data.color' if 'inherit:darker(*)' provided`, t => {
+    const colorGenerator = getColorGenerator('inherit:darker(1)');
+    const color          = '#FF0000';
+
+    t.is(typeof colorGenerator, 'function');
+    t.deepEqual(colorGenerator({ data: { color }}), d3.rgb(color).darker(1));
+});
+
+test(`getColorGenerator() 'inherit:darker(*)' should support floats`, t => {
+    const colorGenerator = getColorGenerator('inherit:darker(.3)');
+    const color          = '#FF0000';
+
+    t.is(typeof colorGenerator, 'function');
+    t.deepEqual(colorGenerator({ data: { color }}), d3.rgb(color).darker(.3));
+});
+
+test(`getColorGenerator() should return a function to use brighter 'data.color' if 'inherit:brighter(*)' provided`, t => {
+    const colorGenerator = getColorGenerator('inherit:brighter(1)');
+    const color          = '#FF0000';
+
+    t.is(typeof colorGenerator, 'function');
+    t.deepEqual(colorGenerator({ data: { color }}), d3.rgb(color).brighter(1));
+});
+
+test(`getColorGenerator() 'inherit:brighter(*)' should support floats`, t => {
+    const colorGenerator = getColorGenerator('inherit:brighter(.3)');
+    const color          = '#FF0000';
+
+    t.is(typeof colorGenerator, 'function');
+    t.deepEqual(colorGenerator({ data: { color }}), d3.rgb(color).brighter(.3));
+});
+
+test(`getColorGenerator() should throw on invalid directive`, t => {
+    t.throws(() => {
+        getColorGenerator('invalid');
+    }, 'Unable to determine color generator');
+});