fix tests for preconditions

index.js

@@ -23,6 +23,7 @@ bitcore.util = {};
 bitcore.util.bitcoin = require('./lib/util/bitcoin');
 bitcore.util.buffer = require('./lib/util/buffer');
 bitcore.util.js = require('./lib/util/js');
+bitcore.util.preconditions = require('./lib/util/preconditions');
 
 // transport
 bitcore.transport = {};

test/util/preconditions.js

@@ -2,9 +2,10 @@
 
 var should = require('chai').should();
 
-var errors = require('../../lib/errors');
-var $ = require('../../lib/util/preconditions');
-var PrivateKey = require('../../lib/privatekey');
+var bitcore = require('../..');
+var errors = bitcore.errors;
+var $ = bitcore.util.preconditions;
+var PrivateKey = bitcore.PrivateKey;
 
 describe('preconditions', function() {