Add __repr__ method to metric objects, make them debug friendly. (#481)

* Add __repr__ method to metric objects, make them debug friendly.
* Added __str__ too, update repr to use parenthesis to be more pythonic.

Signed-off-by: Asher Foa <[email protected]>

Author: asherf

prometheus_client/metrics.py

@@ -80,6 +80,13 @@ def collect(self):
             metric.add_sample(self._name + suffix, labels, value)
         return [metric]
 
+    def __str__(self):
+        return "{0}:{1}".format(self._type, self._name)
+
+    def __repr__(self):
+        metric_type = type(self)
+        return "{0}.{1}({2})".format(metric_type.__module__, metric_type.__name__, self._name)
+
     def __init__(self,
                  name,
                  documentation,

tests/test_core.py

@@ -30,9 +30,13 @@ def test_increment(self):
         self.assertEqual(1, self.registry.get_sample_value('c_total'))
         self.counter.inc(7)
         self.assertEqual(8, self.registry.get_sample_value('c_total'))
+    
+    def test_repr(self):
+        self.assertEqual(repr(self.counter), "prometheus_client.metrics.Counter(c)")
 
     def test_negative_increment_raises(self):
         self.assertRaises(ValueError, self.counter.inc, -1)
+    
 
     def test_function_decorator(self):
         @self.counter.count_exceptions(ValueError)
@@ -83,6 +87,9 @@ class TestGauge(unittest.TestCase):
     def setUp(self):
         self.registry = CollectorRegistry()
         self.gauge = Gauge('g', 'help', registry=self.registry)
+    
+    def test_repr(self):
+        self.assertEqual(repr(self.gauge), "prometheus_client.metrics.Gauge(g)")
 
     def test_gauge(self):
         self.assertEqual(0, self.registry.get_sample_value('g'))
@@ -180,6 +187,9 @@ def setUp(self):
         self.registry = CollectorRegistry()
         self.summary = Summary('s', 'help', registry=self.registry)
 
+    def test_repr(self):
+        self.assertEqual(repr(self.summary), "prometheus_client.metrics.Summary(s)")
+
     def test_summary(self):
         self.assertEqual(0, self.registry.get_sample_value('s_count'))
         self.assertEqual(0, self.registry.get_sample_value('s_sum'))
@@ -269,6 +279,10 @@ def setUp(self):
         self.histogram = Histogram('h', 'help', registry=self.registry)
         self.labels = Histogram('hl', 'help', ['l'], registry=self.registry)
 
+    def test_repr(self):
+        self.assertEqual(repr(self.histogram), "prometheus_client.metrics.Histogram(h)")
+        self.assertEqual(repr(self.labels), "prometheus_client.metrics.Histogram(hl)")
+
     def test_histogram(self):
         self.assertEqual(0, self.registry.get_sample_value('h_bucket', {'le': '1.0'}))
         self.assertEqual(0, self.registry.get_sample_value('h_bucket', {'le': '2.5'}))
@@ -373,6 +387,10 @@ def setUp(self):
         self.info = Info('i', 'help', registry=self.registry)
         self.labels = Info('il', 'help', ['l'], registry=self.registry)
 
+    def test_repr(self):
+        self.assertEqual(repr(self.info), "prometheus_client.metrics.Info(i)")
+        self.assertEqual(repr(self.labels), "prometheus_client.metrics.Info(il)")
+
     def test_info(self):
         self.assertEqual(1, self.registry.get_sample_value('i_info', {}))
         self.info.info({'a': 'b', 'c': 'd'})