Added unit tests for cache

Author: thewhaleking

tests/unit_tests/test_cache.py

@@ -0,0 +1,83 @@
+import asyncio
+import pytest
+from unittest import mock
+
+from async_substrate_interface.utils.cache import CachedFetcher
+
+
+@pytest.mark.asyncio
+async def test_cached_fetcher_fetches_and_caches():
+    """Tests that CachedFetcher correctly fetches and caches results."""
+    # Setup
+    mock_method = mock.AsyncMock(side_effect=lambda x: f"result_{x}")
+    fetcher = CachedFetcher(max_size=2, method=mock_method)
+
+    # First call should trigger the method
+    result1 = await fetcher.execute("key1")
+    assert result1 == "result_key1"
+    mock_method.assert_awaited_once_with("key1")
+
+    # Second call with the same key should use the cache
+    result2 = await fetcher.execute("key1")
+    assert result2 == "result_key1"
+    # Ensure the method was NOT called again
+    assert mock_method.await_count == 1
+
+    # Third call with a new key triggers a method call
+    result3 = await fetcher.execute("key2")
+    assert result3 == "result_key2"
+    assert mock_method.await_count == 2
+
+@pytest.mark.asyncio
+async def test_cached_fetcher_handles_inflight_requests():
+    """Tests that CachedFetcher waits for in-flight results instead of re-fetching."""
+    # Create an event to control when the mock returns
+    event = asyncio.Event()
+
+    async def slow_method(x):
+        await event.wait()
+        return f"slow_result_{x}"
+
+    fetcher = CachedFetcher(max_size=2, method=slow_method)
+
+    # Start first request
+    task1 = asyncio.create_task(fetcher.execute("key1"))
+    await asyncio.sleep(0.1)  # Let the task start and be inflight
+
+    # Second request for the same key while the first is in-flight
+    task2 = asyncio.create_task(fetcher.execute("key1"))
+    await asyncio.sleep(0.1)
+
+    # Release the inflight request
+    event.set()
+    result1, result2 = await asyncio.gather(task1, task2)
+    assert result1 == result2 == "slow_result_key1"
+
+@pytest.mark.asyncio
+async def test_cached_fetcher_propagates_errors():
+    """Tests that CachedFetcher correctly propagates errors."""
+    async def error_method(x):
+        raise ValueError("Boom!")
+
+    fetcher = CachedFetcher(max_size=2, method=error_method)
+
+    with pytest.raises(ValueError, match="Boom!"):
+        await fetcher.execute("key1")
+
+@pytest.mark.asyncio
+async def test_cached_fetcher_eviction():
+    """Tests that LRU eviction works in CachedFetcher."""
+    mock_method = mock.AsyncMock(side_effect=lambda x: f"val_{x}")
+    fetcher = CachedFetcher(max_size=2, method=mock_method)
+
+    # Fill cache
+    await fetcher.execute("key1")
+    await fetcher.execute("key2")
+    assert list(fetcher._cache.cache.keys()) == list(fetcher._cache.cache.keys())
+
+    # Insert a new key to trigger eviction
+    await fetcher.execute("key3")
+    # key1 should be evicted
+    assert "key1" not in fetcher._cache.cache
+    assert "key2" in fetcher._cache.cache
+    assert "key3" in fetcher._cache.cache