Allow skipping test cases that need Internet access

Mark test cases that need Internet access and allow skipping them by
setting the environment variable `NO_INTERNET`.

Forwarded: saltstack#16
Signed-off-by: Benjamin Drung <bdrung@debian.org>

src/pytestskipmarkers/utils/markers.py

@@ -137,6 +137,9 @@ def skip_if_no_remote_network() -> Optional[str]:
         str: The reason for the skip.
         None: Should not be skipped.
     """
+    if os.environ.get("NO_INTERNET"):
+        return "Environment variable NO_INTERNET is set"
+
     # We are using the google.com DNS records as numerical IPs to avoid
     # DNS look ups which could greatly slow down this check
     has_remote_network = False

tests/unit/utils/markers/test_skip_if_no_remote_network.py

@@ -4,6 +4,7 @@
 """
 Test the "skip_if_no_remote_network" marker helper.
 """
+import os
 from unittest import mock
 
 import pytestskipmarkers.utils.markers as markers
@@ -22,3 +23,12 @@ def test_no_remote_network():
         skip_reason = markers.skip_if_no_remote_network()
         assert skip_reason is not None
         assert skip_reason == "No internet network connection was detected"
+
+
+def test_remote_network_with_no_internet():
+    environ = os.environ.copy()
+    environ["NO_INTERNET"] = "1"
+    with mock.patch("os.environ", return_value=environ):
+        skip_reason = markers.skip_if_no_remote_network()
+        assert skip_reason is not None
+        assert skip_reason == "Environment variable NO_INTERNET is set"