Make unit test deterministic by mocking network connection (#17614)

Author: iliakur

datadog_checks_dev/changelog.d/17614.fixed

@@ -0,0 +1,3 @@
+CheckEndpoints lets its clients pass alternative to `urllib.requests.urlopen` which:
+1. exposes the external dependency more clearly
+2. supports deterministic testing

datadog_checks_dev/datadog_checks/dev/conditions.py

@@ -67,11 +67,13 @@ def __init__(
         timeout=1,  # type: int
         attempts=60,  # type: int
         wait=1,  # type: int
+        send_request=None,
     ):
         self.endpoints = [endpoints] if isinstance(endpoints, string_types) else endpoints
         self.timeout = timeout
         self.attempts = attempts
         self.wait = wait
+        self.send_request = urlopen if send_request is None else send_request
 
     def __call__(self):
         last_endpoint = ''
@@ -81,12 +83,12 @@ def __call__(self):
             for endpoint in self.endpoints:
                 last_endpoint = endpoint
                 try:
-                    request = urlopen(endpoint, timeout=self.timeout)
+                    response = self.send_request(endpoint, timeout=self.timeout)
                 except Exception as e:
                     last_error = str(e)
                     break
                 else:
-                    status_code = request.getcode()
+                    status_code = response.getcode()
                     if 400 <= status_code < 600:
                         last_error = 'status {}'.format(status_code)
                         break

datadog_checks_dev/tests/test_conditions.py

@@ -5,13 +5,19 @@
 import sys
 
 import pytest
+from six.moves.urllib.response import addinfourl
 
 from datadog_checks.dev.conditions import CheckCommandOutput, CheckDockerLogs, CheckEndpoints, WaitFor
 from datadog_checks.dev.errors import RetryError
 from datadog_checks.dev.subprocess import run_command
 
 from .common import not_windows_ci
 
+try:
+    from unittest import mock  # Python 3
+except ImportError:
+    import mock  # Python 2
+
 HERE = os.path.dirname(os.path.abspath(__file__))
 DOCKER_DIR = os.path.join(HERE, 'docker')
 
@@ -97,6 +103,8 @@ def test_fail(self):
             check_endpoints()
 
     def test_success(self):
-        check_endpoints = CheckEndpoints(['https://google.com', 'https://bing.com'])
+        mock_resp = mock.create_autospec(addinfourl)
+        mock_resp.getcode.return_value = 200
+        check_endpoints = CheckEndpoints(['https://test.com'], send_request=lambda *args, **kwargs: mock_resp)
 
         check_endpoints()