Add v1 future incompatibility warning

holidays/__init__.py

@@ -12,7 +12,13 @@
 
 # flake8: noqa: F403
 
+import warnings
+
 from holidays.constants import *
+from holidays.deprecation import (
+    FUTURE_INCOMPATIBILITY_WARNING_TEMPLATE,
+    FutureIncompatibilityWarning,
+)
 from holidays.holiday_base import *
 from holidays.registry import EntityLoader
 from holidays.utils import *
@@ -22,3 +28,8 @@
 
 EntityLoader.load("countries", globals())
 EntityLoader.load("financial", globals())
+
+warnings.warn(
+    FUTURE_INCOMPATIBILITY_WARNING_TEMPLATE.format(version=__version__),
+    FutureIncompatibilityWarning,
+)

holidays/deprecation.py

@@ -0,0 +1,33 @@
+#  holidays
+#  --------
+#  A fast, efficient Python library for generating country, province and state
+#  specific sets of holidays on the fly. It aims to make determining whether a
+#  specific date is a holiday as fast and flexible as possible.
+#
+#  Authors: Vacanza Team and individual contributors (see AUTHORS file)
+#           dr-prodigy <dr.prodigy.github@gmail.com> (c) 2017-2023
+#           ryanss <ryanssdev@icloud.com> (c) 2014-2017
+#  Website: https://github.com/vacanza/python-holidays
+#  License: MIT (see LICENSE file)
+
+FUTURE_INCOMPATIBILITY_WARNING_TEMPLATE = """
+
+This is a future version incompatibility warning from Python Holidays library v{version}
+to inform you about an upcoming change in our API versioning strategy that may affect your
+project's dependencies. Starting from version 1.0 onwards, we will be following a loose form of
+Semantic Versioning (SemVer) to provide clearer communication regarding any potential breaking
+changes.
+
+This means that while we strive to maintain backward compatibility, there might be occasional
+updates that introduce breaking changes to our API. To ensure the stability of your projects,
+we highly recommend pinning the version of our API that you rely on. You can pin your current
+holidays v0.x dependency (e.g., holidays=={version}) or limit it (e.g., holidays<1.0) in order to
+avoid potentially unwanted upgrade to the version 1.0 when it's released (ETA 2024Q4 - 2025Q1).
+
+If you have any questions or concerns regarding this change, please don't hesitate to reach out
+to us via https://github.com/vacanza/python-holidays/discussions/1800.
+"""
+
+
+class FutureIncompatibilityWarning(DeprecationWarning):
+    pass

pyproject.toml

@@ -71,6 +71,9 @@ disable_error_code = ["override"]
 module = "holidays.groups.*"
 disable_error_code = "attr-defined"
 
+[tool.pytest.ini_options]
+addopts = "-p no:warnings"
+
 [tool.rstcheck]
 ignore_directives = ["automodule", "autosummary"]
 ignore_languages = ["python"]

tests/countries/test_eswatini.py

@@ -110,7 +110,3 @@ def test_swaziland_deprecation_warning(self):
         warnings.simplefilter("default")
         with self.assertWarns(Warning):
             holidays.Swaziland()
-
-        warnings.simplefilter("error")
-        with self.assertRaises(Warning):
-            holidays.Swaziland()

tests/countries/test_south_korea.py

@@ -541,10 +541,6 @@ def test_korea_deprecation_warning(self):
         with self.assertWarns(Warning):
             Korea()
 
-        warnings.simplefilter("error")
-        with self.assertRaises(Warning):
-            Korea()
-
     def test_2020_all(self):
         self.assertHolidays(
             SouthKorea(categories=(BANK, PUBLIC), years=2020),

tox.ini

@@ -34,7 +34,3 @@ deps =
 commands =
     pre-commit autoupdate
     pre-commit run --all-files
-
-[pytest]
-filterwarnings =
-    ignore:The --rsyncdir .* are deprecated:DeprecationWarning