Simplify opencensus quickstart tests. (#2990)

* Simplify opencensus tests.

* Fix lint error

* Only check stdout.

* Remember this is python, not java.

opencensus/metrics_quickstart.py

@@ -62,12 +62,13 @@ def main():
     # Record 100 fake latency values between 0 and 5 seconds.
     for num in range(100):
         ms = random() * 5 * 1000
-        print("Latency {}: {}".format(num, ms))
 
         mmap = stats.stats.stats_recorder.new_measurement_map()
         mmap.measure_float_put(LATENCY_MS, ms)
         mmap.record()
 
+        print("Fake latency recorded ({}: {})".format(num, ms))
+
     # Keep the thread alive long enough for the exporter to export at least
     # once.
     time.sleep(65)

opencensus/metrics_quickstart_test.py

@@ -12,69 +12,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from unittest import mock
-import unittest
+import metrics_quickstart
 
-from opencensus.ext.stackdriver import stats_exporter
-from opencensus.stats import aggregation
-from opencensus.stats import measure
-from opencensus.stats import stats
-from opencensus.stats import view
 
-
-class TestMetricsQuickstart(unittest.TestCase):
-    """Sanity checks for the OpenCensus metrics quickstart examples.
-
-    These tests check that a few basic features of the library work as expected
-    in order for the demo to run. See the opencensus and
-    opencensus-ext-stackdriver source for actual library tests.
-    """
-    def test_measure_creation(self):
-        measure.MeasureFloat(
-            "task_latency",
-            "The task latency in milliseconds",
-            "ms")
-
-    def test_view_creation(self):
-        test_view = view.View(
-            "task_latency_distribution",
-            "The distribution of the task latencies",
-            [],
-            mock.Mock(),
-            aggregation.DistributionAggregation([1.0, 2.0, 3.0]))
-        # Check that metric descriptor conversion doesn't crash
-        test_view.get_metric_descriptor()
-
-    # Don't modify global stats
-    @mock.patch('opencensus.ext.stackdriver.stats_exporter.stats.stats',
-                stats._Stats())
-    def test_measurement_map_record(self):
-        mock_measure = mock.Mock()
-        mock_measure_name = mock.Mock()
-        mock_measure.name = mock_measure_name
-        mock_view = mock.Mock()
-        mock_view.columns = []
-        mock_view.measure = mock_measure
-
-        stats.stats.view_manager.register_view(mock_view)
-
-        mmap = stats.stats.stats_recorder.new_measurement_map()
-        mmap.measure_float_put(mock_measure, 1.0)
-        mmap.record()
-
-        # Reaching into the stats internals here to check that recording the
-        # measurement map affects view data.
-        m2vd = (stats.stats.view_manager.measure_to_view_map
-                ._measure_to_view_data_list_map)
-        self.assertIn(mock_measure_name, m2vd)
-        [view_data] = m2vd[mock_measure_name]
-        agg_data = view_data.tag_value_aggregation_data_map[tuple()]
-        agg_data.add_sample.assert_called_once()
-
-    @mock.patch('opencensus.ext.stackdriver.stats_exporter'
-                '.monitoring_v3.MetricServiceClient')
-    def test_new_stats_exporter(self, mock_client):
-        transport = stats_exporter.new_stats_exporter()
-        self.assertIsNotNone(transport)
-        self.assertIsNotNone(transport.options)
-        self.assertIsNotNone(transport.options.project_id)
+def test_quickstart_main(capsys):
+    # Run the quickstart, making sure that it runs successfully
+    metrics_quickstart.main()
+    output = capsys.readouterr()
+    assert "Fake latency recorded" in output.out