Mocha/Promise error detection.

gistfile1.js

var falafel = require('falafel');

var fs = require('fs');
var file = process.argv[2];
var src = fs.readFileSync(file).toString();

var output = falafel(src, {loc: true}, function (node) {
  if (node.type === 'Identifier' && node.name === "it") {
    var testBody = node.parent.arguments[1].body.body
    var lastStatement = testBody[testBody.length - 1];

    if(lastStatement.type !== 'ReturnStatement') {
      console.log(file + ":" + lastStatement.loc.start.line);
    }
  }
});