Support injecting into single-param arrow functions

lib/utils.js

@@ -14,6 +14,8 @@ var OUTPUT_SUFFIX_PRIVATE = '_'
 
 var NODE_NAME_RE = /^[!?+%]?[a-zA-Z_*][-a-zA-Z0-9_]*(?:[.][a-zA-Z_][a-zA-Z0-9_]*)*(?:[._](?:[0-9]+|[*]))?$/
 
+var SINGLE_PARAM_ARROW_FN_RE = /^(\w+)\s+=>/
+
 var DYNAMIC_NODE_REF = '_dynamic'
 var INPUT_ARG_PREFIX = 'args.'
 var LAZY_ARG_PREFIX = 'lazyargs.'
@@ -549,12 +551,19 @@ function parseFnParams(fn) {
     keywordIndex = ctorMatch.index
   }
 
-  var lParenIdx = fnStr.indexOf('(', keywordIndex)
+  var arrowMatch = SINGLE_PARAM_ARROW_FN_RE.exec(fnStr)
+    , lParenIdx = fnStr.indexOf('(', keywordIndex)
     , rParenIdx = fnStr.indexOf(')', keywordIndex)
     , paramsStr
     , params
     , i
 
+  // ES6 arrow functions with a single parameter don't require parentheses
+  // around the parameter, so we must handle them separately
+  if (arrowMatch) {
+    return [arrowMatch[1]]
+  }
+
   // Check for existence of parentheses
   if (lParenIdx === -1 || rParenIdx === -1) {
     throw new Error('Invalid function')