Trouble using for in loop with mocha

events.js

/* Mocha test
   to use:
     npm install mocha
     mocha <filename>
   or
     npm test
*/

var assert = require('assert');
var tzwhere = require('../lib/index');
var util = require('util');

// Expected format for locations.json: [utc_time, lat, lng, time_zone_offset]
var testLocations = require('./locations.json');

describe('Test locations', function () {
  //var startTime = Date().getTime();
  console.time('tzOffsetAt test locations');

  //var testLocation = testLocations[0];
  for(var testLocation in testLocations) {
    it('should properly determine the times on either side of daylight savings', function (done) {
      var testDate = new Date(testLocation[0])
      var testLat = testLocation[1];
      var testLng = testLocation[2];
      var testOffset = testLocation[3];

      var tzwhereOffset = tzwhere.tzOffsetAt(testLat, testLng, testDate) / 1000;

      util.debug(util.inspect(testLocation));
      util.debug(util.inspect(testOffset));
      util.debug(util.inspect(tzwhereOffset));

      assert.equal(tzwhereOffset, testOffset);
      return done();
    });
}

  //var endTime = Date().getTime();
  console.log(testLocations.length + ' locations tested');
  console.timeEnd('tzOffsetAt test locations');

  after(function () {
    console.log(util.inspect(process.memoryUsage()));
  });
});

This fails.
But if I comment out lines 21 and 37, and comment in line 20 (i.e. skip the loop of testLocations and just use the zeroth element via [0]) then it works.
It still fails when I reduce the contents of ./locations.json to a single element, so I don't believe it's an issue with extra data.

this is just a normal function scoping issue, you can try doing something like:

for (var foo ...) {
  (function(foo){

  })(foo)
}

then it becomes scoped to that function