Use open() instead of file()

The later isn't supported in Python3

Change-Id: I44e9e7d21d59a82648a5a78a0ebcae8f0317bb6f

jenkins_jobs/builder.py

@@ -616,7 +616,7 @@ class CacheStorage(object):
         if flush or not os.path.isfile(self.cachefilename):
             self.data = {}
         else:
-            with file(self.cachefilename, 'r') as yfile:
+            with open(self.cachefilename, 'r') as yfile:
                 self.data = yaml.load(yfile)
         logger.debug("Using cache: '{0}'".format(self.cachefilename))
 

tests/cachestorage/test_cachestorage.py

@@ -13,6 +13,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import os
 import testtools
 
 import jenkins_jobs
@@ -32,3 +33,14 @@ class TestCaseCacheStorage(testtools.TestCase):
             with mock.patch('os.path.isfile', return_value=False):
                 jenkins_jobs.builder.CacheStorage("dummy")
             save_mock.assert_called_once_with()
+
+    @mock.patch('jenkins_jobs.builder.CacheStorage.get_cache_dir',
+                lambda x: '/bad/file')
+    def test_cache_file(self):
+        """
+        Test providing a cachefile.
+        """
+        test_file = os.path.abspath(__file__)
+        with mock.patch('os.path.join', return_value=test_file):
+            with mock.patch('yaml.load'):
+                jenkins_jobs.builder.CacheStorage("dummy").data = None