Support disabling dark mode globally (#2530)

* Support disabling dark mode globally

* Update changelog

CHANGELOG.md

@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Make `outline` configurable, `outline-none` more accessible by default, and add `outline-black` and `outline-white` ([#2460](https://github.com/tailwindlabs/tailwindcss/pull/2460))
 - Add additional small `rotate` and `skew` values ([#2528](https://github.com/tailwindlabs/tailwindcss/pull/2528))
 - Add `xl`, `2xl`, and `3xl` border radius values ([#2529](https://github.com/tailwindlabs/tailwindcss/pull/2529))
+- Support disabling dark mode variants globally ([#2530](https://github.com/tailwindlabs/tailwindcss/pull/2530))
 
 ## [1.8.12] - 2020-10-07
 

__tests__/darkMode.test.js

@@ -143,6 +143,29 @@ test('dark mode variants can be generated using the class strategy', () => {
   })
 })
 
+test('dark mode variants can be disabled', () => {
+  const input = `
+    @variants dark {
+      .text-red {
+        color: red;
+      }
+    }
+  `
+
+  const expected = `
+    .text-red {
+      color: red;
+    }
+  `
+
+  expect.assertions(2)
+
+  return run(input, { dark: false }).then(result => {
+    expect(result.css).toMatchCss(expected)
+    expect(result.warnings().length).toBe(0)
+  })
+})
+
 test('dark mode variants stack with other variants', () => {
   const input = `
     @variants responsive, dark, hover, focus {

src/flagged/darkModeVariantPlugin.js

@@ -4,6 +4,10 @@ export default function({ addVariant, config, postcss, prefix }) {
   addVariant(
     'dark',
     ({ container, separator, modifySelectors }) => {
+      if (config('dark') === false) {
+        return postcss.root()
+      }
+
       if (config('dark') === 'media') {
         const modified = modifySelectors(({ selector }) => {
           return buildSelectorVariant(selector, 'dark', separator, message => {