--- a/src/lib.rs	Sun Jul 17 16:36:56 2016 +0200
+++ b/src/lib.rs	Sun Jul 17 16:37:14 2016 +0200
@@ -13,6 +13,7 @@
 mod filter_block;
 mod log;
 mod memtable;
+mod merging_iter;
 mod options;
 mod skipmap;
 mod snapshot;
@@ -20,6 +21,8 @@
 mod types;
 mod write_batch;
 
+mod test_util;
+
 pub use types::Comparator;
 
 #[cfg(test)]

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/test_util.rs	Sun Jul 17 16:37:14 2016 +0200
@@ -0,0 +1,69 @@
+use types::LdbIterator;
+use types::Comparator;
+use types::StandardComparator;
+
+use std::cmp::Ordering;
+
+pub struct TestLdbIter<'a> {
+    v: Vec<(&'a [u8], &'a [u8])>,
+    ix: usize,
+    init: bool,
+}
+
+impl<'a> TestLdbIter<'a> {
+    pub fn new(c: Vec<(&'a [u8], &'a [u8])>) -> TestLdbIter<'a> {
+        return TestLdbIter {
+            v: c,
+            ix: 0,
+            init: false,
+        };
+    }
+}
+
+impl<'a> Iterator for TestLdbIter<'a> {
+    type Item = (&'a [u8], &'a [u8]);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.ix == self.v.len() {
+            return None;
+        } else if !self.init {
+            self.init = true;
+            Some(self.v[self.ix])
+        } else {
+            self.ix += 1;
+            Some(self.v[self.ix - 1])
+        }
+    }
+}
+
+impl<'a> LdbIterator for TestLdbIter<'a> {
+    fn reset(&mut self) {
+        self.ix = 0;
+        self.init = false;
+    }
+    fn current(&self) -> Option<Self::Item> {
+        if self.init && self.ix < self.v.len() {
+            Some(self.v[self.ix])
+        } else {
+            None
+        }
+    }
+    fn valid(&self) -> bool {
+        self.init
+    }
+    fn seek(&mut self, k: &[u8]) {
+        self.ix = 0;
+        while self.ix < self.v.len() &&
+              StandardComparator::cmp(self.v[self.ix].0, k) == Ordering::Less {
+            self.ix += 1;
+        }
+    }
+    fn prev(&mut self) -> Option<Self::Item> {
+        if !self.init || self.ix == 0 {
+            None
+        } else {
+            self.ix -= 1;
+            Some(self.v[self.ix])
+        }
+    }
+}