Test for punctuator tokens in lookupBlockType. Fixes jshintgh-1856

Closes jshint#1857

src/jshint.js

@@ -4412,23 +4412,23 @@ var JSHINT = (function () {
     var i = -1;
     var bracketStack = 0;
     var ret = {};
-    if (_.contains(["[", "{"], state.tokens.curr.value))
+    if (checkPunctuators(state.tokens.curr, ["[", "{"]))
       bracketStack += 1;
     do {
       pn = (i === -1) ? state.tokens.next : peek(i);
       pn1 = peek(i + 1);
       i = i + 1;
-      if (_.contains(["[", "{"], pn.value)) {
+      if (checkPunctuators(pn, ["[", "{"])) {
         bracketStack += 1;
-      } else if (_.contains(["]", "}"], pn.value)) {
+      } else if (checkPunctuators(pn, ["]", "}"])) {
         bracketStack -= 1;
       }
       if (pn.identifier && pn.value === "for" && bracketStack === 1) {
         ret.isCompArray = true;
         ret.notJson = true;
         break;
       }
-      if (_.contains(["}", "]"], pn.value) && bracketStack === 0) {
+      if (checkPunctuators(pn, ["}", "]"]) && bracketStack === 0) {
         if (pn1.value === "=") {
           ret.isDestAssign = true;
           ret.notJson = true;
@@ -4446,6 +4446,11 @@ var JSHINT = (function () {
     return ret;
   };
 
+  // Test whether a given token is a punctuator matching one of the specified values
+  function checkPunctuators(token, values) {
+    return token.type === "(punctuator)" && _.contains(values, token.value);
+  }
+
   // Check whether this function has been reached for a destructuring assign with undeclared values
   function destructuringAssignOrJsonValue() {
     // lookup for the assignment (esnext only)

tests/unit/parser.js

@@ -2722,6 +2722,25 @@ exports["test: array comprehension"] = function (test) {
   test.done();
 };
 
+exports["gh-1856 mistakenly identified as array comprehension"] = function (test) {
+  var code = [
+    "function main(value) {",
+    "  var result = ['{'],",
+    "      key;",
+    "  for (key in value) {",
+    "    result.push(key);",
+    "  }",
+    "  return result;",
+    "}",
+    "main({abc:true});"
+  ];
+
+  TestRun(test)
+    .test(code);
+
+  test.done();
+};
+
 exports["test: moz-style array comprehension"] = function (test) {
   // example taken from https://developer.mozilla.org/en-US/docs/JavaScript/New_in_JavaScript/1.7
   var code = [