pow chain store tests added

lighthouse/db/Cargo.toml

@@ -11,3 +11,4 @@ rocksdb = "0.10.1"
 ssz = { path = "../../beacon_chain/utils/ssz" }
 ssz_helpers = { path = "../../beacon_chain/utils/ssz_helpers" }
 types = { path = "../../beacon_chain/types" }
+rand = "0.5.5"

lighthouse/db/src/stores/pow_chain_store.rs

@@ -4,6 +4,7 @@ use super::{
     DBError,
 };
 use super::POW_CHAIN_DB_COLUMN as DB_COLUMN;
+extern crate rand;
 
 pub struct PoWChainStore<T>
     where T: ClientDB
@@ -31,4 +32,42 @@ impl<T: ClientDB> PoWChainStore<T> {
     }
 }
 
-// TODO: add tests once a memory-db is implemented
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use super::super::super::MemoryDB;
+
+    #[test]
+    fn test_put_block_hash() {
+        let db = Arc::new(MemoryDB::open());
+        let store = PoWChainStore::new(db.clone());
+
+        let hash: &[u8] = &[rand::random()];
+        store.put_block_hash(hash);
+
+        assert!(db.exists(DB_COLUMN, hash).unwrap());
+    }
+
+    #[test]
+    fn test_block_hash_exists() {
+        let db = Arc::new(MemoryDB::open());
+        let store = PoWChainStore::new(db.clone());
+
+        let hash: &[u8] = &[rand::random()];
+        db.put(DB_COLUMN, hash, &[0]);
+
+        assert!(store.block_hash_exists(hash).unwrap());
+    }
+
+    #[test]
+    fn test_block_hash_does_not_exist() {
+        let db = Arc::new(MemoryDB::open());
+        let store = PoWChainStore::new(db.clone());
+
+        let hash: &[u8] = &[rand::random()];
+        let other_hash: &[u8] = &[rand::random()];
+        db.put(DB_COLUMN, hash, &[0]);
+
+        assert!(!store.block_hash_exists(other_hash).unwrap());
+    }
+}