add test case

tests/segment_range_oob.rs

@@ -0,0 +1,62 @@
+use lsm_tree::{AbstractTree, Config};
+use test_log::test;
+
+const ITEM_COUNT: usize = 100;
+
+#[test]
+fn segment_range_out_of_bounds_lo() -> lsm_tree::Result<()> {
+    let folder = tempfile::tempdir()?.into_path();
+
+    let tree = Config::new(folder)
+        .data_block_size(1_024)
+        .index_block_size(1_024)
+        .open()?;
+
+    for key in ('h'..='o').map(|c| c.to_string()) {
+        let value = nanoid::nanoid!();
+        tree.insert(key, value.as_bytes(), 0);
+    }
+    tree.flush_active_memtable(0)?;
+
+    assert_eq!(4, tree.range(..="k").count());
+    assert_eq!(4, tree.range(..="k").rev().count());
+
+    assert_eq!(4, tree.range("0"..="k").count());
+    assert_eq!(4, tree.range("0"..="k").rev().count());
+
+    Ok(())
+}
+
+#[test]
+fn segment_range_out_of_bounds_hi() -> lsm_tree::Result<()> {
+    let folder = tempfile::tempdir()?.into_path();
+
+    let tree = Config::new(folder)
+        .data_block_size(1_024)
+        .index_block_size(1_024)
+        .open()?;
+
+    for x in 0..ITEM_COUNT as u64 {
+        let key = x.to_be_bytes();
+        let value = nanoid::nanoid!();
+        tree.insert(key, value.as_bytes(), 0);
+    }
+    tree.flush_active_memtable(0)?;
+
+    assert_eq!(50, tree.range((50u64.to_be_bytes())..).count());
+    assert_eq!(50, tree.range((50u64.to_be_bytes())..).rev().count());
+
+    assert_eq!(
+        50,
+        tree.range((50u64.to_be_bytes())..(150u64.to_be_bytes()))
+            .count()
+    );
+    assert_eq!(
+        50,
+        tree.range((50u64.to_be_bytes())..(150u64.to_be_bytes()))
+            .rev()
+            .count()
+    );
+
+    Ok(())
+}