Support passing config object under config key

__tests__/customConfig.test.js

@@ -95,6 +95,44 @@ test('custom config path can be passed using `config` property in an object', ()
     })
 })
 
+test('custom config can be passed under the `config` property', () => {
+  return postcss([
+    tailwind({
+      config: {
+        theme: {
+          screens: {
+            mobile: '400px',
+          },
+        },
+      },
+    }),
+  ])
+    .process(
+      `
+        @responsive {
+          .foo {
+            color: blue;
+          }
+        }
+      `,
+      { from: undefined }
+    )
+    .then(result => {
+      const expected = `
+        .foo {
+          color: blue;
+        }
+        @media (min-width: 400px) {
+          .mobile\\:foo {
+            color: blue;
+          }
+        }
+      `
+
+      expect(result.css).toMatchCss(expected)
+    })
+})
+
 test('tailwind.config.js is picked up by default', () => {
   return inTempDirectory(() => {
     fs.writeFileSync(

src/index.js

@@ -13,18 +13,27 @@ import { defaultConfigFile } from './constants'
 import defaultConfig from '../stubs/defaultConfig.stub.js'
 
 function resolveConfigPath(filePath) {
+  // require('tailwindcss')({ theme: ..., variants: ... })
   if (_.isObject(filePath) && !_.has(filePath, 'config') && !_.isEmpty(filePath)) {
     return undefined
   }
 
-  if (_.isObject(filePath) && _.has(filePath, 'config')) {
+  // require('tailwindcss')({ config: 'custom-config.js' })
+  if (_.isObject(filePath) && _.has(filePath, 'config') && _.isString(filePath.config)) {
     return path.resolve(filePath.config)
   }
 
+  // require('tailwindcss')({ config: { theme: ..., variants: ... } })
+  if (_.isObject(filePath) && _.has(filePath, 'config') && _.isObject(filePath.config)) {
+    undefined
+  }
+
+  // require('tailwindcss')('custom-config.js')
   if (_.isString(filePath)) {
     return path.resolve(filePath)
   }
 
+  // require('tailwindcss')
   try {
     const defaultConfigPath = path.resolve(defaultConfigFile)
     fs.accessSync(defaultConfigPath)
@@ -43,7 +52,10 @@ const getConfigFunction = config => () => {
     delete require.cache[require.resolve(config)]
   }
 
-  return resolveConfig([_.isObject(config) ? config : require(config), defaultConfig])
+  return resolveConfig([
+    _.isObject(config) ? _.get(config, 'config', config) : require(config),
+    defaultConfig,
+  ])
 }
 
 const plugin = postcss.plugin('tailwind', config => {