When labelnames is falsy, pass an empty tuple to __init__ (prometheus#147)

savoie · brian-brazil · commit e5e73e521dbb · 2017-03-20T22:58:20.000Z
diff --git a/prometheus_client/core.py b/prometheus_client/core.py
@@ -536,7 +536,7 @@ def init(name, documentation, labelnames=(), namespace='', subsystem='', registr
                     raise ValueError('Reserved label metric name: ' + l)
             collector = _LabelWrapper(cls, name, labelnames, **kwargs)
         else:
-            collector = cls(name, labelnames, (), **kwargs)
+            collector = cls(name, (), (), **kwargs)
 
         if not _METRIC_NAME_RE.match(full_name):
             raise ValueError('Invalid metric name: ' + full_name)
diff --git a/tests/test_core.py b/tests/test_core.py
@@ -303,6 +303,10 @@ def test_invalid_names_raise(self):
         self.assertRaises(ValueError, Counter, 'c', '', labelnames=['__reserved'])
         self.assertRaises(ValueError, Summary, 'c', '', labelnames=['quantile'])
 
+    def test_empty_labels_list(self):
+        h = Histogram('h', 'help', [], registry=self.registry)
+        self.assertEqual(0, self.registry.get_sample_value('h_sum'))
+
 
 class TestMetricFamilies(unittest.TestCase):
     def setUp(self):
