diff --git a/lighthouse/db/mod.rs b/lighthouse/db/mod.rs
index 33f97cc37..c85eaf18b 100644
--- a/lighthouse/db/mod.rs
+++ b/lighthouse/db/mod.rs
@@ -1,29 +1,11 @@
 extern crate rocksdb;
 
 mod disk_db;
+mod traits;
 
 pub use self::disk_db::DiskDB;
-
-type DBValue = Vec<u8>;
-
-#[derive(Debug)]
-pub struct DBError {
-    message: String
-}
-
-impl DBError {
-    pub fn new(message: String) -> Self {
-        Self { message }
-    }
-}
-
-pub trait ClientDB: Sync + Send {
-    fn create_col(&mut self, col: &str)
-        -> Result<(), DBError>;
-
-    fn get(&self, col: &str, key: &[u8])
-        -> Result<Option<DBValue>, DBError>;
-
-    fn put(&self, col: &str, key: &[u8], val: &[u8])
-        -> Result<(), DBError>;
-}
+pub use self::traits::{
+    DBError,
+    DBValue,
+    ClientDB,
+};
diff --git a/lighthouse/db/traits.rs b/lighthouse/db/traits.rs
new file mode 100644
index 000000000..97759d3b7
--- /dev/null
+++ b/lighthouse/db/traits.rs
@@ -0,0 +1,30 @@
+pub type DBValue = Vec<u8>;
+
+#[derive(Debug)]
+pub struct DBError {
+    pub message: String
+}
+
+impl DBError {
+    pub fn new(message: String) -> Self {
+        Self { message }
+    }
+}
+
+/// A generic database to be used by the "client' (i.e.,
+/// the lighthouse blockchain client).
+///
+/// The purpose of having this generic trait is to allow the
+/// program to use a persistent on-disk database during production,
+/// but use a transient database during tests.
+pub trait ClientDB: Sync + Send {
+    fn create_col(&mut self, col: &str)
+        -> Result<(), DBError>;
+
+    fn get(&self, col: &str, key: &[u8])
+        -> Result<Option<DBValue>, DBError>;
+
+    fn put(&self, col: &str, key: &[u8], val: &[u8])
+        -> Result<(), DBError>;
+}
+