Treat deprecation warnings as errors

pyproject.toml

@@ -57,7 +57,18 @@ addopts = [
   "--tb=native",
   "--strict-markers"
 ]
-
+filterwarnings = [
+  # elevate conda's deprecated warning to an error
+  "error::PendingDeprecationWarning:conda",
+  "error::DeprecationWarning:conda",
+  # elevate conda-libmamba-solver's deprecated warning to an error
+  "error::PendingDeprecationWarning:conda_libmamba_solver",
+  "error::DeprecationWarning:conda_libmamba_solver",
+  # ignore conda-index error
+  "ignore::PendingDeprecationWarning:conda_index",
+  "ignore::DeprecationWarning:conda_index",
+  "ignore:Python 3.14 will, by default, filter extracted tar archives and reject files or modify their metadata:DeprecationWarning",
+]
 markers = [
   "integration: integration tests that usually require an internet connect",
   "slow: slow running tests",

tests/conftest.py

@@ -2,5 +2,8 @@
 # Copyright (C) 2023 conda
 # SPDX-License-Identifier: BSD-3-Clause
 
-from conda.testing import conda_cli, path_factory, tmp_env  # noqa
-from conda.testing.fixtures import clear_subdir_cache, tmpdir  # noqa
+pytest_plugins = (
+    # Add testing fixtures and internal pytest plugins here
+    "conda.testing",
+    "conda.testing.fixtures",
+)