test: an explicit test of N5CacheTest

src/test/java/org/janelia/saalfeldlab/n5/cache/N5CacheTest.java

@@ -0,0 +1,121 @@
+package org.janelia.saalfeldlab.n5.cache;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+import com.google.gson.JsonElement;
+
+public class N5CacheTest {
+
+	@Test
+	public void cacheBackingTest() {
+
+		final DummyBackingStorage backingStorage = new DummyBackingStorage();
+		final N5JsonCache cache = new N5JsonCache(backingStorage::backingAttrs, backingStorage::exists,
+				backingStorage::isGroup, backingStorage::isDataset, backingStorage::list);
+
+		// check existance, ensure backing storage is only called once
+		assertEquals(0, backingStorage.existsCallCount);
+		cache.exists("a");
+		assertEquals(1, backingStorage.existsCallCount);
+		cache.exists("a");
+		assertEquals(1, backingStorage.existsCallCount);
+
+		// check existance of new group, ensure backing storage is only called one more time
+		cache.exists("b");
+		assertEquals(2, backingStorage.existsCallCount);
+		cache.exists("b");
+		assertEquals(2, backingStorage.existsCallCount);
+
+		// check isDataset, ensure backing storage is only called when expected
+		// isDataset is called by exists, so should have been called twice here
+		assertEquals(2, backingStorage.isDatasetCallCount);
+		cache.isDataset("a");
+		assertEquals(2, backingStorage.isDatasetCallCount);
+
+		assertEquals(2, backingStorage.isDatasetCallCount);
+		cache.isDataset("b");
+		assertEquals(2, backingStorage.isDatasetCallCount);
+
+		// check isGroup, ensure backing storage is only called when expected
+		// isGroup is called by exists, so should have been called twice here
+		assertEquals(2, backingStorage.isGroupCallCount);
+		cache.isDataset("a");
+		assertEquals(2, backingStorage.isGroupCallCount);
+
+		assertEquals(2, backingStorage.isGroupCallCount);
+		cache.isDataset("b");
+		assertEquals(2, backingStorage.isGroupCallCount);
+
+		// similarly check list, ensure backing storage is only called when expected
+		// list is called by exists, so should have been called twice here
+		assertEquals(2, backingStorage.listCallCount);
+		cache.list("a");
+		assertEquals(2, backingStorage.listCallCount);
+
+		assertEquals(2, backingStorage.listCallCount);
+		cache.list("b");
+		assertEquals(2, backingStorage.listCallCount);
+
+		// finally check getAttributes
+		// it is not called by exists (since it needs the cache key)
+		assertEquals(0, backingStorage.attrCallCount);
+		cache.getAttributes("a", "foo");
+		assertEquals(1, backingStorage.attrCallCount);
+		cache.getAttributes("a", "foo");
+		assertEquals(1, backingStorage.attrCallCount);
+		cache.getAttributes("a", "bar");
+		assertEquals(2, backingStorage.attrCallCount);
+		cache.getAttributes("a", "bar");
+		assertEquals(2, backingStorage.attrCallCount);
+
+		cache.getAttributes("b", "foo");
+		assertEquals(3, backingStorage.attrCallCount);
+		cache.getAttributes("b", "foo");
+		assertEquals(3, backingStorage.attrCallCount);
+		cache.getAttributes("b", "bar");
+		assertEquals(4, backingStorage.attrCallCount);
+		cache.getAttributes("b", "bar");
+		assertEquals(4, backingStorage.attrCallCount);
+
+	}
+
+	protected static class DummyBackingStorage {
+
+		int attrCallCount = 0;
+		int existsCallCount = 0;
+		int isGroupCallCount = 0;
+		int isDatasetCallCount = 0;
+		int listCallCount = 0;
+
+		public DummyBackingStorage() {
+		}
+
+		public JsonElement backingAttrs(final String key, final String cacheKey) {
+			attrCallCount++;
+			return null;
+		}
+
+		public boolean exists(final String key) {
+			existsCallCount++;
+			return true;
+		}
+
+		public boolean isGroup(final String key) {
+			isGroupCallCount++;
+			return true;
+		}
+
+		public boolean isDataset(final String key) {
+			isDatasetCallCount++;
+			return true;
+		}
+
+		public String[] list(final String key) {
+			listCallCount++;
+			return new String[] { "list" };
+		}
+	}
+
+}