feat(ifUtils): add configurable ifXXX and ifNotXXX methods (#8)

closes #7

src/get-if-utils.js

@@ -31,16 +31,16 @@ export {getIfUtils}
  * This returns an object with methods to help you conditionally set values to your webpack configuration object.
  * @param  {Object|string} env This would be either the `env` object from webpack (function config API) or the value of
  * `process.env.NODE_ENV`.
+ * @param  {Array} vars A list of valid environments if utils are generated for
  * @return {IfUtils} the IfUtils object for the given environment
  */
-function getIfUtils(env) {
+function getIfUtils(env, vars = ['production', 'prod', 'test', 'development', 'dev']) {
   env = typeof env === 'string' ? {[env]: true} : env
   if (typeof env !== 'object') {
     throw new Error(
       `webpack-config-utils:getIfUtils: env passed should be a string/Object. Was ${JSON.stringify(env)}`
     )
   }
-  const vars = ['production', 'prod', 'test', 'development', 'dev']
   return vars.reduce((utils, variable) => {
     const envValue = !!env[variable]
     const capitalVariable = capitalizeWord(variable)

src/get-if-utils.test.js

@@ -15,6 +15,16 @@ test('has if and ifNot methods for the expected environment values', t => {
   const diff = difference(methods, expectedMethods)
   t.deepEqual(diff, [])
 })
+test('has ifXXX and ifNotXXX methods for the expected environment values', t => {
+  const expectedMethods = [
+    'ifFoo', 'ifNotFoo',
+    'ifBar', 'ifNotBar',
+  ]
+  const utils = getIfUtils({}, ['foo', 'bar'])
+  const methods = Object.keys(utils)
+  const diff = difference(methods, expectedMethods)
+  t.deepEqual(diff, [])
+})
 
 test('works with string values', t => {
   const {ifProduction} = getIfUtils('production')
@@ -36,3 +46,11 @@ test('returns true/false when given no arguments', t => {
   t.is(ifProd(), false)
   t.is(ifNotDev(), true)
 })
+
+test('returns true/false for custom ifXXX when given no arguments', t => {
+  const {ifWatch, ifProd, ifNotDev, ifTest} = getIfUtils('watch', ['prod', 'dev', 'watch'])
+  t.is(ifWatch(), true)
+  t.is(ifProd(), false)
+  t.is(ifNotDev(), true)
+  t.is(ifTest, undefined)
+})