old_contents: module.exports = {
    isFunc: function(f) {
      return typeof f === 'function';
    }
  };
  
new_contents: var isFunc = require('../src/util').isFunc;
  
  module.exports = {
    isFunc:     isFunc,
    isFakeFunc: function(func) {
      if (func.expectations === undefined) {
        return false;
      }
      if (func.calls === undefined) {
        return false;
      }
      if (func.expectations.length !== 0) {
        return false;
      }
      return isFunc(func.invoke);
    }
  };
  
subject: Add TestHelper.isFakeFunc