test: disjoint segment scan, closes #26

tests/tree_disjoint_iter.rs

@@ -0,0 +1,71 @@
+use lsm_tree::Config;
+use std::sync::Arc;
+
+macro_rules! iter_closed {
+    ($iter:expr) => {
+        assert!($iter.next().is_none(), "iterator should be closed (done)");
+        assert!(
+            $iter.next_back().is_none(),
+            "iterator should be closed (done)"
+        );
+    };
+}
+
+#[test]
+fn tree_disjoint_iter() -> lsm_tree::Result<()> {
+    let tempdir = tempfile::tempdir()?;
+    let tree = crate::Config::new(&tempdir).open()?;
+
+    // IMPORTANT: Purposefully mangle the order of IDs
+    // to make sure stuff is still getting read in the correct order
+    // even if written out of order
+    let ids = [["d", "e", "f"], ["a", "b", "c"]];
+
+    for batch in ids {
+        for id in batch {
+            tree.insert(id, vec![], 0);
+        }
+        tree.flush_active_memtable()?;
+    }
+
+    // NOTE: Forwards
+
+    let iter = tree.iter();
+    let mut iter = iter.into_iter();
+
+    assert_eq!(Arc::from(*b"a"), iter.next().unwrap()?.0);
+    assert_eq!(Arc::from(*b"b"), iter.next().unwrap()?.0);
+    assert_eq!(Arc::from(*b"c"), iter.next().unwrap()?.0);
+    assert_eq!(Arc::from(*b"d"), iter.next().unwrap()?.0);
+    assert_eq!(Arc::from(*b"e"), iter.next().unwrap()?.0);
+    assert_eq!(Arc::from(*b"f"), iter.next().unwrap()?.0);
+    iter_closed!(iter);
+
+    // NOTE: Reverse
+
+    let iter = tree.iter();
+    let mut iter = iter.into_iter().rev();
+
+    assert_eq!(Arc::from(*b"f"), iter.next().unwrap()?.0);
+    assert_eq!(Arc::from(*b"e"), iter.next().unwrap()?.0);
+    assert_eq!(Arc::from(*b"d"), iter.next().unwrap()?.0);
+    assert_eq!(Arc::from(*b"c"), iter.next().unwrap()?.0);
+    assert_eq!(Arc::from(*b"b"), iter.next().unwrap()?.0);
+    assert_eq!(Arc::from(*b"a"), iter.next().unwrap()?.0);
+    iter_closed!(iter);
+
+    // NOTE: Ping Pong
+
+    let iter = tree.iter();
+    let mut iter = iter.into_iter();
+
+    assert_eq!(Arc::from(*b"a"), iter.next().unwrap()?.0);
+    assert_eq!(Arc::from(*b"f"), iter.next_back().unwrap()?.0);
+    assert_eq!(Arc::from(*b"b"), iter.next().unwrap()?.0);
+    assert_eq!(Arc::from(*b"e"), iter.next_back().unwrap()?.0);
+    assert_eq!(Arc::from(*b"c"), iter.next().unwrap()?.0);
+    assert_eq!(Arc::from(*b"d"), iter.next_back().unwrap()?.0);
+    iter_closed!(iter);
+
+    Ok(())
+}