Skip tests for optional serializer dependencies if not installed

2 files changed, 27 insertions, 6 deletions

diff --git a/tests/conftest.py b/tests/conftest.py
index 96c35a7..b242946 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -11,6 +11,7 @@ https://requests-mock.readthedocs.io/en/latest/adapter.html
 import os
 from datetime import datetime, timedelta
 from functools import wraps
+from importlib import import_module
 from logging import basicConfig, getLogger
 from pathlib import Path
 from unittest.mock import MagicMock
@@ -224,6 +225,12 @@ def get_mock_response(
     )
 
 
+def assert_delta_approx_equal(dt1: datetime, dt2: datetime, target_delta, threshold_seconds=2):
+    """Assert that the given datetimes are approximately ``target_delta`` seconds apart"""
+    diff_in_seconds = (dt2 - dt1).total_seconds()
+    assert abs(diff_in_seconds - target_delta) <= threshold_seconds
+
+
 def fail_if_no_connection(connect_timeout: float = 1.0) -> bool:
     """Decorator for testing a backend connection. This will intentionally cause a test failure if
     the wrapped function doesn't have dependencies installed, doesn't connect after a short timeout,
@@ -247,7 +254,16 @@ def fail_if_no_connection(connect_timeout: float = 1.0) -> bool:
     return decorator
 
 
-def assert_delta_approx_equal(dt1: datetime, dt2: datetime, target_delta, threshold_seconds=2):
-    """Assert that the given datetimes are approximately ``target_delta`` seconds apart"""
-    diff_in_seconds = (dt2 - dt1).total_seconds()
-    assert abs(diff_in_seconds - target_delta) <= threshold_seconds
+def is_installed(module_name: str) -> bool:
+    """Check if a given dependency is installed"""
+    try:
+        import_module(module_name)
+        return True
+    except ImportError:
+        return False
+
+
+def skip_missing_deps(module_name: str) -> pytest.Mark:
+    return pytest.mark.skipif(
+        not is_installed(module_name), reason=f'{module_name} is not installed'
+    )
diff --git a/tests/unit/test_serializers.py b/tests/unit/test_serializers.py
index 6f6f61e..9a611ab 100644
--- a/tests/unit/test_serializers.py
+++ b/tests/unit/test_serializers.py
@@ -9,8 +9,6 @@ from unittest.mock import patch
 from uuid import uuid4
 
 import pytest
-from itsdangerous import Signer
-from itsdangerous.exc import BadSignature
 
 from requests_cache import (
     CachedResponse,
@@ -21,6 +19,7 @@ from requests_cache import (
     safe_pickle_serializer,
     utf8_encoder,
 )
+from tests.conftest import skip_missing_deps
 
 
 def test_stdlib_json():
@@ -35,6 +34,7 @@ def test_stdlib_json():
     reload(requests_cache.serializers.preconf)
 
 
+@skip_missing_deps('ujson')
 def test_ujson():
     import ujson
 
@@ -43,6 +43,7 @@ def test_ujson():
     assert module_json is ujson
 
 
+@skip_missing_deps('bson')
 def test_standalone_bson():
     """Handle different method names for standalone bson codec vs pymongo"""
     import requests_cache.serializers.preconf
@@ -80,7 +81,11 @@ def test_optional_dependencies():
     reload(requests_cache.serializers.preconf)
 
 
+@skip_missing_deps('itsdangerous')
 def test_cache_signing(tempfile_path):
+    from itsdangerous import Signer
+    from itsdangerous.exc import BadSignature
+
     serializer = safe_pickle_serializer(secret_key=str(uuid4()))
     session = CachedSession(tempfile_path, serializer=serializer)
     assert isinstance(session.cache.responses.serializer.stages[-1].obj, Signer)