Extract mergeConfigWithDefaults for easier testability

Author: adamwathan

__tests__/mergeConfigWithDefaults.test.js

@@ -0,0 +1,79 @@
+import mergeConfigWithDefaults from '../src/util/mergeConfigWithDefaults'
+
+test('missing top level keys are pulled from the default config', () => {
+  const userConfig = {
+    colors:  { red: '#ff0000' },
+    modules:  {},
+    options:  {},
+  }
+
+  const defaultConfig = {
+    colors:  { green: '#00ff00' },
+    screens: {
+      sm: '576px'
+    },
+    modules:  {},
+    options:  {},
+  }
+
+  const result = mergeConfigWithDefaults(userConfig, defaultConfig)
+
+  expect(result).toEqual({
+    colors:  { red: '#ff0000' },
+    screens: {
+      sm: '576px'
+    },
+    modules:  {},
+    options:  {},
+  })
+})
+
+test('user modules are merged with default modules', () => {
+  const userConfig = {
+    modules:  { flexbox: false },
+    options:  {},
+  }
+
+  const defaultConfig = {
+    modules:  {
+      flexbox: ['responsive'],
+      textAlign: ['responsive'],
+    },
+    options:  {},
+  }
+
+  const result = mergeConfigWithDefaults(userConfig, defaultConfig)
+
+  expect(result).toEqual({
+    modules:  {
+      flexbox: false,
+      textAlign: ['responsive'],
+    },
+    options:  {},
+  })
+})
+
+test('user options are merged with default options', () => {
+  const userConfig = {
+    modules:  {},
+    options:  { prefix: 'tw-' },
+  }
+
+  const defaultConfig = {
+    modules:  {},
+    options:  {
+      prefix: '-',
+      important: false,
+    },
+  }
+
+  const result = mergeConfigWithDefaults(userConfig, defaultConfig)
+
+  expect(result).toEqual({
+    modules:  {},
+    options:  {
+      prefix: 'tw-',
+      important: false,
+    },
+  })
+})

src/index.js

@@ -15,13 +15,7 @@ import substituteResponsiveAtRules from './lib/substituteResponsiveAtRules'
 import substituteScreenAtRules from './lib/substituteScreenAtRules'
 import substituteClassApplyAtRules from './lib/substituteClassApplyAtRules'
 
-function mergeConfigWithDefaults(config) {
-  const defaultConfig = require('../defaultConfig')()
-  _.defaults(config, defaultConfig)
-  config.options = _.defaults(config.options, defaultConfig.options)
-  config.options.modules = _.defaults(config.options.modules, defaultConfig.options.modules)
-  return config
-}
+import mergeConfigWithDefaults from './util/mergeConfigWithDefaults'
 
 const plugin = postcss.plugin('tailwind', config => {
   const plugins = []
@@ -36,7 +30,7 @@ const plugin = postcss.plugin('tailwind', config => {
     }
 
     delete require.cache[require.resolve(path.resolve(config))]
-    return mergeConfigWithDefaults(require(path.resolve(config)))
+    return mergeConfigWithDefaults(require(path.resolve(config)), require('../defaultConfig')())
   }
 
   return postcss(

src/util/mergeConfigWithDefaults.js

@@ -0,0 +1,8 @@
+import _ from 'lodash'
+
+export default function(userConfig, defaultConfig) {
+  _.defaults(userConfig, defaultConfig)
+  userConfig.modules = _.defaults(userConfig.modules, defaultConfig.modules)
+  userConfig.options = _.defaults(userConfig.options, defaultConfig.options)
+  return userConfig
+}