fix: Keep analytics events with zero context cache capacity

ldclient/impl/lru_cache.py

@@ -19,6 +19,8 @@ def get(self, key):
     '''
 
     def put(self, key, value):
+        if self.capacity <= 0:
+            return False
         found = key in self.cache
         if found:
             self.cache.move_to_end(key)

ldclient/testing/impl/events/test_async_event_processor.py

@@ -272,6 +272,31 @@ async def test_two_events_for_same_context_only_produce_one_index_event():
         assert output[3]['kind'] == 'summary'
 
 
+@pytest.mark.parametrize(
+    "event,expected_kinds",
+    [
+        pytest.param(EventInputIdentify(timestamp, context), ['identify', 'identify'], id='identify'),
+        pytest.param(EventInputCustom(timestamp, context, 'eventkey', {'thing': 'stuff'}, 1.5), ['index', 'custom', 'index', 'custom'], id='custom'),
+        pytest.param(
+            EventInputEvaluation(timestamp, context, flag.key, flag, 1, 'value', None, 'default', None, True),
+            ['index', 'feature', 'index', 'feature', 'summary'],
+            id='feature',
+        ),
+    ],
+)
+async def test_events_are_delivered_with_zero_context_keys_capacity(event, expected_kinds):
+    mock_http = MockAioHttp()
+    async with make_processor(mock_http, context_keys_capacity=0) as ep:
+        ep.send_event(event)
+        ep.send_event(event)
+
+        output = await flush_and_get_events(ep, mock_http)
+        assert [item['kind'] for item in output] == expected_kinds
+        for item in output:
+            if item['kind'] != 'summary':
+                assert item['context'] == context.to_dict()
+
+
 async def test_nontracked_events_are_summarized():
     mock_http = MockAioHttp()
     async with make_processor(mock_http) as ep:

ldclient/testing/impl/events/test_event_processor.py

@@ -384,6 +384,30 @@ def test_two_events_for_same_context_only_produce_one_index_event():
         check_summary_event(output[3])
 
 
+@pytest.mark.parametrize(
+    "event,expected_kinds",
+    [
+        pytest.param(EventInputIdentify(timestamp, context), ['identify', 'identify'], id='identify'),
+        pytest.param(EventInputCustom(timestamp, context, 'eventkey', {'thing': 'stuff'}, 1.5), ['index', 'custom', 'index', 'custom'], id='custom'),
+        pytest.param(
+            EventInputEvaluation(timestamp, context, flag.key, flag, 1, 'value', None, 'default', None, True),
+            ['index', 'feature', 'index', 'feature', 'summary'],
+            id='feature',
+        ),
+    ],
+)
+def test_events_are_delivered_with_zero_context_keys_capacity(event, expected_kinds):
+    with DefaultTestProcessor(context_keys_capacity=0) as ep:
+        ep.send_event(event)
+        ep.send_event(event)
+
+        output = flush_and_get_events(ep)
+        assert [item['kind'] for item in output] == expected_kinds
+        for item in output:
+            if item['kind'] != 'summary':
+                assert item['context'] == context.to_dict()
+
+
 def test_new_index_event_is_added_if_context_cache_has_been_cleared():
     with DefaultTestProcessor(context_keys_flush_interval=0.1) as ep:
         e0 = EventInputEvaluation(timestamp, context, flag.key, flag, 1, 'value1', None, 'default', None, True)

ldclient/testing/impl/test_lru_cache.py

@@ -1,6 +1,19 @@
+import pytest
+
 from ldclient.impl.lru_cache import SimpleLRUCache
 
 
+@pytest.mark.parametrize("capacity", [0, -1])
+def test_non_positive_capacity_does_not_retain_values(capacity):
+    lru = SimpleLRUCache(capacity)
+    assert lru.put("a", True) is False
+    assert lru.get("a") is None
+    assert lru.put("a", True) is False
+    assert lru.put("b", True) is False
+    assert lru.get("a") is None
+    assert lru.get("b") is None
+
+
 def test_retains_values_up_to_capacity():
     lru = SimpleLRUCache(3)
     assert lru.put("a", True) is False