diff --git a/contracts/Marketplace.sol b/contracts/Marketplace.sol
index 3787d51..c973851 100644
--- a/contracts/Marketplace.sol
+++ b/contracts/Marketplace.sol
@@ -11,7 +11,6 @@ import "./libs/DAL.sol";
 contract Marketplace is Collateral, Proofs {
   using DAL for DAL.Database;
   using EnumerableSet for EnumerableSet.Bytes32Set;
-  using DAL for EnumerableSet.Bytes32Set;
 
   uint256 public immutable collateral;
   MarketplaceFunds private funds;
diff --git a/contracts/libs/DAL.sol b/contracts/libs/DAL.sol
index 8cc34a4..df87d1b 100644
--- a/contracts/libs/DAL.sol
+++ b/contracts/libs/DAL.sol
@@ -84,8 +84,8 @@ library DAL {
   function insert(Database storage db,
                   RequestId requestId,
                   ClientId clientId,
-                  Ask memory ask,
-                  Content memory content,
+                  Ask calldata ask,
+                  Content calldata content,
                   uint256 expiry,
                   bytes32 nonce)
     internal
@@ -104,6 +104,18 @@ library DAL {
     r.nonce = nonce;
   }
 
+  function insert(Database storage db, Slot memory slot ) internal {
+    require(!_isDefault(slot.id), "slot id required");
+    require(!isDefault(slot.requestId), "request id required");
+    require(exists(db, slot.requestId), "request does not exist");
+    require(!exists(db, slot.id), "slot already exists");
+    require(exists(db, slot.host), "host does not exist");
+    db.slots[slot.id] = slot;
+
+    Request storage request = db.requests[slot.requestId];
+    request.slots.add(SlotId.unwrap(slot.id));
+  }
+
   function insert(Database storage db, ClientId clientId) internal {
     require (!exists(db, clientId), "client already exists");
     require (!_isDefault(clientId), "address required");
@@ -120,18 +132,6 @@ library DAL {
     // NOTE: by default db.hosts[host].slots already exists but has a default value
   }
 
-  function insert(Database storage db, Slot memory slot ) internal {
-    require(!_isDefault(slot.id), "slot id required");
-    require(!isDefault(slot.requestId), "request id required");
-    require(exists(db, slot.requestId), "request does not exist");
-    require(!exists(db, slot.id), "slot already exists");
-    require(exists(db, slot.host), "host does not exist");
-    db.slots[slot.id] = slot;
-
-    Request storage request = db.requests[slot.requestId];
-    request.slots.add(SlotId.unwrap(slot.id));
-  }
-
   function insert(Database storage db,
                   EnumerableSet.Bytes32Set storage requests,
                   RequestId requestId)
@@ -251,6 +251,17 @@ library DAL {
     delete db.requests[request.id];
   }
 
+  function remove(Database storage db, Slot storage slot) internal {
+    require(exists(db, slot.requestId), "request does not exist");
+    Host storage host = db.hosts[slot.host];
+    bytes32 bSlotId = SlotId.unwrap(slot.id);
+    require(!host.slots.contains(bSlotId), "active slot refs");
+
+    Request storage request = db.requests[slot.requestId];
+    request.slots.remove(bSlotId);
+    delete db.slots[slot.id];
+  }
+
   function remove(Database storage db, Client storage client) internal {
     require(client.requests.length() == 0, "active request refs");
 
@@ -263,17 +274,6 @@ library DAL {
     delete db.hosts[host.id];
   }
 
-  function remove(Database storage db, Slot storage slot) internal {
-    require(exists(db, slot.requestId), "request does not exist");
-    Host storage host = db.hosts[slot.host];
-    bytes32 bSlotId = SlotId.unwrap(slot.id);
-    require(!host.slots.contains(bSlotId), "active slot refs");
-
-    Request storage request = db.requests[slot.requestId];
-    request.slots.remove(bSlotId);
-    delete db.slots[slot.id];
-  }
-
   function remove(Database storage db,
                   EnumerableSet.Bytes32Set storage requests,
                   RequestId requestId)
diff --git a/contracts/libs/TestDAL.sol b/contracts/libs/TestDAL.sol
new file mode 100644
index 0000000..ebca1a1
--- /dev/null
+++ b/contracts/libs/TestDAL.sol
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+import "@openzeppelin/contracts/utils/structs/EnumerableSet.sol";
+import "./DAL.sol";
+
+// exposes public functions for testing
+contract TestDAL {
+  using DAL for DAL.Database;
+  using EnumerableSet for EnumerableSet.Bytes32Set;
+
+  event OperationResult(bool result);
+
+  DAL.Database private _db;
+
+  function insertRequest(DAL.RequestId requestId,
+                         DAL.ClientId clientId,
+                         DAL.Ask calldata ask,
+                         DAL.Content calldata content,
+                         uint256 expiry,
+                         bytes32 nonce)
+    public
+  {
+    _db.insert(requestId, clientId, ask, content, expiry, nonce);
+  }
+
+  function insertSlot(DAL.Slot memory slot) public {
+    _db.insert(slot);
+  }
+
+  function insertClient(DAL.ClientId clientId) public {
+    _db.insert(clientId);
+  }
+
+  function insertHost(DAL.HostId hostId) public {
+    _db.insert(hostId);
+  }
+
+  function insertHostRequest(DAL.HostId hostId,
+                             DAL.RequestId requestId)
+    public
+  {
+    DAL.Host storage host = _db.select(hostId);
+    _db.insert(host.requests, requestId);
+  }
+
+  function insertClientRequest(DAL.ClientId clientId,
+                               DAL.RequestId requestId)
+    public
+  {
+    DAL.Client storage client = _db.select(clientId);
+    _db.insert(client.requests, requestId);
+  }
+
+  function insertHostSlot(DAL.HostId hostId,
+                          DAL.SlotId slotId)
+    public
+  {
+    DAL.Host storage host = _db.select(hostId);
+    _db.insert(host.slots, slotId);
+  }
+
+  function selectRequest(DAL.RequestId requestId)
+    public
+    view
+    returns (DAL.RequestId,
+             DAL.ClientId,
+             DAL.Ask memory,
+             DAL.Content memory,
+             uint256,
+             bytes32,
+             bytes32[] memory)
+  {
+    DAL.Request storage request = _db.select(requestId);
+    return (request.id,
+            request.client,
+            request.ask,
+            request.content,
+            request.expiry,
+            request.nonce,
+            request.slots.values());
+  }
+
+  function selectSlot(DAL.SlotId slotId)
+    public
+    view
+    returns (DAL.SlotId, DAL.HostId, bool, DAL.RequestId)
+  {
+    DAL.Slot storage slot = _db.select(slotId);
+    return (slot.id, slot.host, slot.hostPaid, slot.requestId);
+  }
+
+  function selectClient(DAL.ClientId clientId)
+    public
+    view
+    returns (DAL.ClientId, bytes32[] memory)
+  {
+    DAL.Client storage client = _db.select(clientId);
+    return (client.id, client.requests.values());
+  }
+
+  function selectHost(DAL.HostId hostId)
+    public
+    view
+    returns (DAL.HostId, bytes32[] memory, bytes32[] memory)
+  {
+    DAL.Host storage host = _db.select(hostId);
+    return (host.id, host.slots.values(), host.requests.values());
+  }
+
+  function requestExists(DAL.RequestId requestId)
+    public
+    view
+    returns (bool)
+  {
+    return _db.exists(requestId);
+  }
+
+  function slotExists(DAL.SlotId slotId)
+    public
+    view
+    returns (bool)
+  {
+    return _db.exists(slotId);
+  }
+
+  function clientExists(DAL.ClientId clientId)
+    public
+    view
+    returns (bool)
+  {
+    return _db.exists(clientId);
+  }
+
+  function hostExists(DAL.HostId hostId)
+    public
+    view
+    returns (bool)
+  {
+    return _db.exists(hostId);
+  }
+
+  function removeRequest(DAL.RequestId requestId) public {
+    DAL.Request storage request = _db.select(requestId);
+    _db.remove(request);
+  }
+
+  function removeSlot(DAL.SlotId slotId) public {
+    DAL.Slot storage slot = _db.select(slotId);
+    _db.remove(slot);
+  }
+
+  function removeClient(DAL.ClientId clientId) public {
+    DAL.Client storage client = _db.select(clientId);
+    _db.remove(client);
+  }
+
+  function removeHost(DAL.HostId hostId) public {
+    DAL.Host storage host = _db.select(hostId);
+    _db.remove(host);
+  }
+
+  function removeClientRequest(DAL.ClientId clientId,
+                               DAL.RequestId requestId)
+    public
+  {
+    DAL.Client storage client = _db.select(clientId);
+    _db.remove(client.requests, requestId);
+  }
+
+  function removeHostRequest(DAL.HostId hostId,
+                             DAL.RequestId requestId)
+    public
+  {
+    DAL.Host storage host = _db.select(hostId);
+    _db.remove(host.requests, requestId);
+  }
+
+  function removeHostSlot(DAL.HostId hostId,
+                          DAL.SlotId slotId)
+    public
+  {
+    DAL.Host storage host = _db.select(hostId);
+    _db.remove(host.slots, slotId);
+  }
+
+  function clearSlots(DAL.HostId hostId,
+                      DAL.RequestId requestId,
+                      uint256 maxIterations)
+    public
+  {
+    DAL.Host storage host = _db.select(hostId);
+    _db.clearSlots(host, requestId, maxIterations);
+  }
+
+  function activeSlots(DAL.HostId hostId)
+    public
+    view
+    returns (DAL.SlotId[] memory)
+  {
+    DAL.Host storage host = _db.select(hostId);
+    return _db.activeSlots(host);
+  }
+
+  function toSlotId(DAL.RequestId requestId, uint256 slotIndex)
+    public
+    pure
+    returns (DAL.SlotId)
+  {
+    return toSlotId(requestId, slotIndex);
+  }
+}
diff --git a/test/DAL.test.js b/test/DAL.test.js
new file mode 100644
index 0000000..c2a9264
--- /dev/null
+++ b/test/DAL.test.js
@@ -0,0 +1,600 @@
+const { ethers } = require("hardhat")
+const { expect, Assertion } = require("chai")
+const { hexlify, randomBytes } = ethers.utils
+const { exampleAddress, exampleRequest, zeroBytesHex } = require("./examples")
+const { slotId, requestId, requestToArray, askToArray } = require("./ids")
+const { BigNumber } = ethers
+const { supportDAL } = require("./dal")
+
+supportDAL(Assertion)
+
+describe("DAL", function () {
+  let account
+  let contract
+  let request
+  let slot
+  let host
+  let client
+
+  describe("Database", function () {
+    beforeEach(async function () {
+      let DAL = await ethers.getContractFactory("TestDAL")
+      contract = await DAL.deploy()
+      ;[account] = await ethers.getSigners()
+      request = await exampleRequest()
+      request.id = requestId(request)
+      request.slots = []
+      client = {
+        id: await exampleAddress(),
+        requests: [],
+      }
+      request.client = client.id
+      host = {
+        id: await exampleAddress(),
+        requests: [],
+        slots: [],
+      }
+      slot = {
+        id: slotId({ request: request.id, index: 0 }),
+        host: host.id,
+        hostPaid: false,
+        requestId: request.id,
+      }
+    })
+
+    describe("Create: successful", function () {
+      it("inserts a request", async function () {
+        await expect(await contract.requestExists(request.id)).to.be.false
+        await contract.insertClient(client.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await expect(await contract.requestExists(request.id)).to.be.true
+      })
+
+      it("inserts a slot", async function () {
+        await expect(await contract.slotExists(slot.id)).to.be.false
+        await contract.insertClient(client.id)
+        await contract.insertHost(host.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertSlot(slot)
+        await expect(await contract.slotExists(slot.id)).to.be.true
+      })
+
+      it("inserts a client", async function () {
+        await expect(await contract.clientExists(client.id)).to.be.false
+        await contract.insertClient(client.id)
+        await expect(await contract.clientExists(client.id)).to.be.true
+      })
+
+      it("inserts a host", async function () {
+        await expect(await contract.hostExists(host.id)).to.be.false
+        await contract.insertHost(host.id)
+        await expect(await contract.hostExists(host.id)).to.be.true
+      })
+
+      it("inserts a host request", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertHost(host.id)
+        await contract.insertHostRequest(host.id, request.id)
+        let [id, slots, requests] = await contract.selectHost(host.id)
+        await expect(requests.includes(request.id)).to.be.true
+      })
+
+      it("inserts a client request", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertClientRequest(client.id, request.id)
+        let [id, requests] = await contract.selectClient(client.id)
+        await expect(requests.includes(request.id)).to.be.true
+      })
+
+      it("inserts a host slot", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertHost(host.id)
+        await contract.insertHostRequest(host.id, request.id)
+        await contract.insertSlot(slot)
+        await contract.insertHostSlot(host.id, slot.id)
+        let [id, slots, requests] = await contract.selectHost(host.id)
+        await expect(slots.includes(slot.id)).to.be.true
+      })
+    })
+
+    describe("Create: failure", function () {
+      it("fails to insert a request when request id not provided", async function () {
+        await expect(await contract.requestExists(request.id)).to.be.false
+        await expect(
+          contract.insertRequest(
+            zeroBytesHex(32),
+            request.client,
+            request.ask,
+            request.content,
+            request.expiry,
+            request.nonce
+          )
+        ).to.be.revertedWith("request id required")
+      })
+      it("fails to insert a request when client id (address) not provided", async function () {
+        await expect(await contract.requestExists(request.id)).to.be.false
+        await expect(
+          contract.insertRequest(
+            request.id,
+            zeroBytesHex(20),
+            request.ask,
+            request.content,
+            request.expiry,
+            request.nonce
+          )
+        ).to.be.revertedWith("client address required")
+      })
+      it("fails to insert a request when client doesn't exist", async function () {
+        await expect(await contract.requestExists(request.id)).to.be.false
+        await expect(
+          contract.insertRequest(
+            request.id,
+            request.client,
+            request.ask,
+            request.content,
+            request.expiry,
+            request.nonce
+          )
+        ).to.be.revertedWith("client does not exist")
+      })
+      it("fails to insert a request when request already exists", async function () {
+        await expect(await contract.requestExists(request.id)).to.be.false
+        await contract.insertClient(client.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await expect(
+          contract.insertRequest(
+            request.id,
+            request.client,
+            request.ask,
+            request.content,
+            request.expiry,
+            request.nonce
+          )
+        ).to.be.revertedWith("request already exists")
+      })
+      it("fails to insert a slot when slot id not provided", async function () {
+        await expect(await contract.requestExists(request.id)).to.be.false
+        slot.id = zeroBytesHex(32)
+        await expect(contract.insertSlot(slot)).to.be.revertedWith(
+          "slot id required"
+        )
+      })
+      it("fails to insert a slot when request id not provided", async function () {
+        await expect(await contract.requestExists(request.id)).to.be.false
+        slot.requestId = zeroBytesHex(32)
+        await expect(contract.insertSlot(slot)).to.be.revertedWith(
+          "request id required"
+        )
+      })
+      it("fails to insert a slot when request id not provided", async function () {
+        await expect(await contract.requestExists(request.id)).to.be.false
+        slot.requestId = zeroBytesHex(32)
+        await expect(contract.insertSlot(slot)).to.be.revertedWith(
+          "request id required"
+        )
+      })
+      it("fails to insert a slot when request doesn't exist", async function () {
+        await expect(await contract.requestExists(request.id)).to.be.false
+        await expect(contract.insertSlot(slot)).to.be.revertedWith(
+          "request does not exist"
+        )
+      })
+      it("fails to insert a slot when the slot already exists", async function () {
+        await expect(await contract.requestExists(request.id)).to.be.false
+        await contract.insertClient(client.id)
+        await contract.insertHost(host.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertSlot(slot)
+        await expect(contract.insertSlot(slot)).to.be.revertedWith(
+          "slot already exists"
+        )
+      })
+      it("fails to insert a slot when the host does not exist", async function () {
+        await expect(await contract.requestExists(request.id)).to.be.false
+        await contract.insertClient(client.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await expect(contract.insertSlot(slot)).to.be.revertedWith(
+          "host does not exist"
+        )
+      })
+      it("fails to insert a client when the client already exists", async function () {
+        await contract.insertClient(client.id)
+        await expect(contract.insertClient(client.id)).to.be.revertedWith(
+          "client already exists"
+        )
+      })
+      it("fails to insert a client when the address wasn't provided", async function () {
+        client.id = zeroBytesHex(20)
+        await expect(contract.insertClient(client.id)).to.be.revertedWith(
+          "address required"
+        )
+      })
+      it("fails to insert a host when the host already exists", async function () {
+        await contract.insertHost(host.id)
+        await expect(contract.insertHost(host.id)).to.be.revertedWith(
+          "host already exists"
+        )
+      })
+      it("fails to insert a host when the address wasn't provided", async function () {
+        host.id = zeroBytesHex(20)
+        await expect(contract.insertHost(host.id)).to.be.revertedWith(
+          "address required"
+        )
+      })
+      it("fails to insert a host request when request doesn't exist", async function () {
+        await contract.insertHost(host.id)
+        await expect(
+          contract.insertHostRequest(host.id, request.id)
+        ).to.be.revertedWith("request does not exist")
+      })
+      it("fails to insert a client request when request doesn't exist", async function () {
+        await contract.insertClient(client.id)
+        await expect(
+          contract.insertClientRequest(client.id, request.id)
+        ).to.be.revertedWith("request does not exist")
+      })
+
+      it("fails to insert a host slot when slot doesn't exist", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertHost(host.id)
+        await expect(
+          contract.insertHostSlot(host.id, slot.id)
+        ).to.be.revertedWith("slot does not exist")
+      })
+
+      it("fails to insert a host slot when host doesn't exist", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await expect(
+          contract.insertHostSlot(host.id, slot.id)
+        ).to.be.revertedWith("Host does not exist")
+      })
+
+      it("fails to insert a host slot when the host request doesn't exist", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertHost(host.id)
+        await contract.insertSlot(slot)
+        await expect(
+          contract.insertHostSlot(host.id, slot.id)
+        ).to.be.revertedWith("slot request not active")
+      })
+    })
+
+    describe("Read: success", function () {
+      it("selects a request", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await expect(await contract.selectRequest(request.id)).to.equalsRequest(
+          request
+        )
+      })
+      it("selects a slot", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertHost(host.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertSlot(slot)
+        await expect(await contract.selectSlot(slot.id)).to.equalsSlot(slot)
+      })
+      it("selects a client", async function () {
+        await contract.insertClient(client.id)
+        await expect(await contract.selectClient(client.id)).to.be.equalsClient(
+          client
+        )
+      })
+      it("selects a host", async function () {
+        await contract.insertHost(host.id)
+        await expect(await contract.selectHost(host.id)).to.be.equalsHost(host)
+      })
+    })
+
+    describe("Read: failure", function () {
+      it("fails to select a request when request doesn't exist", async function () {
+        await expect(contract.selectRequest(request.id)).to.be.revertedWith(
+          "Unknown request"
+        )
+      })
+      it("fails to select a slot when slot is empty", async function () {
+        await expect(contract.selectSlot(slot.id)).to.be.revertedWith(
+          "Slot empty"
+        )
+      })
+      it("fails to select a client when client doesn't exist", async function () {
+        await expect(contract.selectClient(client.id)).to.be.revertedWith(
+          "Client does not exist"
+        )
+      })
+      it("fails to select a host when host doesn't exist", async function () {
+        await expect(contract.selectHost(host.id)).to.be.revertedWith(
+          "Host does not exist"
+        )
+      })
+    })
+
+    describe("Delete: success", function () {
+      it("deletes a request", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.removeRequest(request.id)
+        await expect(contract.selectRequest(request.id)).to.be.revertedWith(
+          "Unknown request"
+        )
+      })
+      it("deletes a slot", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertHost(host.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertSlot(slot)
+        await contract.removeSlot(slot.id)
+        await expect(contract.selectSlot(slot.id)).to.be.revertedWith(
+          "Slot empty"
+        )
+      })
+      it("deletes a client", async function () {
+        await contract.insertClient(client.id)
+        await contract.removeClient(client.id)
+        await expect(contract.selectClient(client.id)).to.be.revertedWith(
+          "Client does not exist"
+        )
+      })
+      it("deletes a host", async function () {
+        await contract.insertHost(host.id)
+        await contract.removeHost(host.id)
+        await expect(contract.selectHost(host.id)).to.be.revertedWith(
+          "Host does not exist"
+        )
+      })
+      it("deletes a client request", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertClientRequest(client.id, request.id)
+        let [id, requests] = await contract.selectClient(client.id)
+        await expect(requests.length).to.equal(1)
+        await contract.removeClientRequest(client.id, request.id)
+        ;[id, requests] = await contract.selectClient(client.id)
+        await expect(requests.length).to.equal(0)
+      })
+      it("deletes a host request", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertHost(host.id)
+        await contract.insertHostRequest(host.id, request.id)
+        let [id, slots, requests] = await contract.selectHost(host.id)
+        await expect(requests.length).to.equal(1)
+        await contract.removeHostRequest(host.id, request.id)
+        ;[id, slots, requests] = await contract.selectHost(host.id)
+        await expect(requests.length).to.equal(0)
+      })
+      it("deletes a host slot", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertHost(host.id)
+        await contract.insertHostRequest(host.id, request.id)
+        await contract.insertSlot(slot)
+        await contract.insertHostSlot(host.id, slot.id)
+        let [id, slots, requests] = await contract.selectHost(host.id)
+        await expect(slots.length).to.equal(1)
+        await contract.removeHostSlot(host.id, slot.id)
+        ;[id, slots, requests] = await contract.selectHost(host.id)
+        await expect(slots.length).to.equal(0)
+      })
+    })
+
+    describe("Delete: failure", function () {
+      it("fails to delete a request when it references slots", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertHost(host.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertSlot(slot)
+        await expect(contract.removeRequest(request.id)).to.be.revertedWith(
+          "references slots"
+        )
+      })
+      it("fails to delete a request when its client has request references", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertHost(host.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertClientRequest(client.id, request.id)
+        await expect(contract.removeRequest(request.id)).to.be.revertedWith(
+          "active request refs"
+        )
+      })
+      it("fails to delete a client when it has request references", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertHost(host.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertClientRequest(client.id, request.id)
+        await expect(contract.removeClient(client.id)).to.be.revertedWith(
+          "active request refs"
+        )
+      })
+      it("fails to delete a request when its host has slot references", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertHost(host.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertSlot(slot)
+        await contract.insertHostRequest(host.id, request.id)
+        await contract.insertHostSlot(host.id, slot.id)
+        await expect(contract.removeSlot(slot.id)).to.be.revertedWith(
+          "active slot refs"
+        )
+      })
+      it("fails to delete a host when it has slot references", async function () {
+        await contract.insertClient(client.id)
+        await contract.insertHost(host.id)
+        await contract.insertRequest(
+          request.id,
+          request.client,
+          request.ask,
+          request.content,
+          request.expiry,
+          request.nonce
+        )
+        await contract.insertSlot(slot)
+        await contract.insertHostRequest(host.id, request.id)
+        await contract.insertHostSlot(host.id, slot.id)
+        await expect(contract.removeHost(host.id)).to.be.revertedWith(
+          "active slot refs"
+        )
+      })
+    })
+  })
+})
diff --git a/test/dal.js b/test/dal.js
new file mode 100644
index 0000000..085feb6
--- /dev/null
+++ b/test/dal.js
@@ -0,0 +1,111 @@
+const { BigNumber } = require("ethers")
+const { hexlify } = ethers.utils
+
+function isBigNumberish(bn) {
+  return bn._isBigNumber === true
+}
+
+function normalizeBn(bn) {
+  return isBigNumberish(bn) ? bn.toNumber() : bn
+}
+
+function supportDAL(Assertion) {
+  Assertion.addMethod("equalsRequest", function (request) {
+    const evmRequest = requestFromArray(this._obj)
+    request.content.por.u = hexlify(request.content.por.u)
+    request.content.por.publicKey = hexlify(request.content.por.publicKey)
+    request.content.por.name = hexlify(request.content.por.name)
+    new Assertion(evmRequest).to.deep.equal(request)
+  })
+  Assertion.addMethod("equalsSlot", function (slot) {
+    const evmSlot = slotFromArray(this._obj)
+    new Assertion(evmSlot).to.deep.equal(slot)
+  })
+  Assertion.addMethod("equalsClient", function (client) {
+    const evmClient = clientFromArray(this._obj)
+    new Assertion(evmClient).to.deep.equal(client)
+  })
+  Assertion.addMethod("equalsHost", function (host) {
+    const evmHost = hostFromArray(this._obj)
+    new Assertion(evmHost).to.deep.equal(host)
+  })
+}
+
+function parse(keys, object) {
+  let obj = {}
+  keys.forEach((key, i) => (obj[key] = normalizeBn(object[i])))
+  return obj
+}
+
+function porFromArray(por) {
+  return {
+    u: por.u,
+    publicKey: por.publicKey,
+    name: por.name,
+  }
+}
+
+function erasureFromArray(erasure) {
+  return {
+    totalChunks: normalizeBn(erasure.totalChunks),
+  }
+}
+
+function contentFromArray(ask) {
+  return {
+    cid: ask.cid,
+    erasure: erasureFromArray(ask.erasure),
+    por: porFromArray(ask.por),
+  }
+}
+
+function askFromArray(ask) {
+  return {
+    slots: normalizeBn(ask.slots),
+    slotSize: normalizeBn(ask.slotSize),
+    duration: normalizeBn(ask.duration),
+    proofProbability: normalizeBn(ask.proofProbability),
+    reward: normalizeBn(ask.reward),
+    maxSlotLoss: normalizeBn(ask.maxSlotLoss),
+  }
+}
+
+function requestFromArray(request) {
+  return {
+    id: request[0],
+    client: request[1],
+    ask: askFromArray(request[2]),
+    content: contentFromArray(request[3]),
+    expiry: normalizeBn(request[4]),
+    nonce: request[5],
+    slots: normalizeBn(request[6]),
+  }
+}
+
+function slotFromArray(slot) {
+  return {
+    id: slot[0],
+    host: slot[1],
+    hostPaid: slot[2],
+    requestId: slot[3],
+  }
+}
+
+function clientFromArray(client) {
+  return {
+    id: client[0],
+    requests: client[1],
+  }
+}
+
+function hostFromArray(host) {
+  return {
+    id: host[0],
+    slots: host[1],
+    requests: host[2],
+  }
+}
+
+module.exports = {
+  supportDAL,
+}
diff --git a/test/examples.js b/test/examples.js
index 50caa46..73bcf96 100644
--- a/test/examples.js
+++ b/test/examples.js
@@ -40,5 +40,12 @@ const exampleLock = async () => {
 const exampleAddress = () => {
   return getAddress(hexlify(randomBytes(20)))
 }
+const zeroBytesHex = (bytes) => {
+  let hex = "0x"
+  for (let i = 0; i < bytes; i++) {
+    hex += "00"
+  }
+  return hex
+}
 
-module.exports = { exampleRequest, exampleLock, exampleAddress }
+module.exports = { exampleRequest, exampleLock, exampleAddress, zeroBytesHex }