Add ability to log warnings during pytest

datadog_checks_dev/datadog_checks/dev/warn.py

@@ -0,0 +1,28 @@
+# (C) Datadog, Inc. 2018
+# All rights reserved
+# Licensed under a 3-clause BSD style license (see LICENSE)
+import warnings
+
+from ._env import e2e_active
+
+_original_formatwarning = warnings.formatwarning
+
+
+def warning(message):
+    # We disable caching of this helper so it can be used multiple times.
+    # https://github.com/python/cpython/blob/9a4758550d96030ee7e7f7c7c68b435db1a2a825/Lib/warnings.py#L362
+    with warnings.catch_warnings():
+        warnings.warn(message, stacklevel=2)
+
+
+def _formatwarning(message, category, filename, lineno, line=None):
+    # Shorten output for occurrences during E2E to just what is necessary for a nice display.
+    if e2e_active():
+        return '{}\n'.format(message)
+
+    return _original_formatwarning(message, category, filename, lineno, line=line)
+
+
+# We can't override `showwarning` as usual because pytest already overrides that for logs.
+# https://github.com/pytest-dev/pytest/blob/b76104e722f41ce367765cd988ee8314d45b20b5/src/_pytest/warnings.py#L75
+warnings.formatwarning = _formatwarning