Add focus-within variant

__tests__/variantsAtRule.test.js

@@ -69,6 +69,27 @@ test('it can generate focus variants', () => {
   })
 })
 
+test('it can generate focus-within variants', () => {
+  const input = `
+    @variants focus-within {
+      .banana { color: yellow; }
+      .chocolate { color: brown; }
+    }
+  `
+
+  const output = `
+      .banana { color: yellow; }
+      .chocolate { color: brown; }
+      .focus-within\\:banana:focus-within { color: yellow; }
+      .focus-within\\:chocolate:focus-within { color: brown; }
+  `
+
+  return run(input).then(result => {
+    expect(result.css).toMatchCss(output)
+    expect(result.warnings().length).toBe(0)
+  })
+})
+
 test('it can generate group-hover variants', () => {
   const input = `
     @variants group-hover {

defaultConfig.stub.js

@@ -828,6 +828,7 @@ module.exports = {
   |   - responsive
   |   - hover
   |   - focus
+  |   - focus-within
   |   - active
   |   - group-hover
   |

src/lib/substituteVariantsAtRules.js

@@ -30,6 +30,7 @@ const variantGenerators = {
   },
   hover: generatePseudoClassVariant('hover'),
   focus: generatePseudoClassVariant('focus'),
+  'focus-within': generatePseudoClassVariant('focus-within'),
   active: generatePseudoClassVariant('active'),
 }
 
@@ -48,7 +49,7 @@ export default function(config) {
 
       atRule.before(atRule.clone().nodes)
 
-      _.forEach(['group-hover', 'hover', 'focus', 'active'], variant => {
+      _.forEach(['group-hover', 'hover', 'focus', 'focus-within', 'active'], variant => {
         if (variants.includes(variant)) {
           variantGenerators[variant](atRule, unwrappedConfig)
         }