Tests and misc fixes

Author: mikera

convex-core/src/main/java/convex/core/data/Address.java

@@ -33,7 +33,7 @@ public final class Address extends ABlobLike<CVMLong> {
 	/**
 	 * The Zero Address
 	 */
-	public static final Address ZERO = Address.create(0);
+	public static final Address ZERO = CACHE[0];
 
 	/**
 	 * The maximum possible Address

convex-core/src/test/java/convex/core/data/IndexTest.java

@@ -34,6 +34,7 @@ public void testEmpty() throws InvalidDataException {
 		assertFalse(m.containsValue(null));
 
 		assertEquals(0L, m.count());
+		assertEquals(0L, m.getDepth());
 		assertSame(m, m.dissoc(Blob.fromHex("cafe")));
 		assertSame(m, m.dissoc(Blob.fromHex("")));
 
@@ -98,7 +99,9 @@ public void testGet() throws InvalidDataException {
 		assertNull(m.get(Samples.MAX_EMBEDDED_STRING)); // needs a blob. String counts as non-existent key
 		assertCVMEquals(17L,m.get(k1));
 
-		assertNull(m.get((Object)null)); // Null counts as non-existent key when used as an Object arg
+		// Null counts as non-existent key when used as an Object arg
+		assertNull(m.get((Object)null)); 
+		assertNull(m.get((ACell)null)); 
 	}
 
 
@@ -238,6 +241,7 @@ public void testSingleEntry() throws InvalidDataException {
 		CVMLong val=RT.cvm(177777L);
 		Index<ABlob, CVMLong> m = Index.create(k, val);
 		assertEquals(1L, m.count());
+		assertEquals(4, m.getDepth());
 
 		assertEquals(val, m.get(k));