new_contents: import re
  
  from tests.helpers import BaseApplicationTest
  
  
  def load_prometheus_metrics(response_bytes):
      return dict(re.findall(rb"(\w+{.+?}) (\d+)", response_bytes))
  
  
  class TestMetrics(BaseApplicationTest):
  
      def test_metrics_page_accessible(self):
          metrics_response = self.client.get('/_metrics')
  
          assert metrics_response.status_code == 200
  
      def test_metrics_page_contents(self):
          metrics_response = self.client.get('/_metrics')
          results = load_prometheus_metrics(metrics_response.data)
          assert (
              b'http_server_requests_total{code="200",host="localhost",method="GET",path="/"}'
          ) in results
  
  
  class TestMetricsPageRegistersPageViews(BaseApplicationTest):
  
      def test_metrics_page_registers_page_views(self):
          expected_metric_name = (
              b'http_server_requests_total{code="200",host="localhost",method="GET",path="/"}'
          )
  
          res = self.client.get('/')
          assert res.status_code == 200
  
          metrics_response = self.client.get('/_metrics')
          results = load_prometheus_metrics(metrics_response.data)
          assert expected_metric_name in results
  
      def test_metrics_page_registers_multiple_page_views(self):
          expected_metric_name = (
              b'http_server_requests_total{code="200",host="localhost",method="GET",path="/"}'
          )
  
          initial_metrics_response = self.client.get('/_metrics')
          initial_results = load_prometheus_metrics(initial_metrics_response.data)
          initial_metric_value = int(initial_results.get(expected_metric_name, 0))
  
          for _ in range(3):
              res = self.client.get('/')
              assert res.status_code == 200
  
          metrics_response = self.client.get('/_metrics')
          results = load_prometheus_metrics(metrics_response.data)
          metric_value = int(results.get(expected_metric_name, 0))
  
          assert expected_metric_name in results
          assert metric_value - initial_metric_value == 3
  
subject: Add standard tests for metrics