Improve errors in findWalletForRedemption function (#652)

Throw error when currently, there are no active wallets in the network
and when the user requested redemption for all active wallets in the
network using the same Bitcoin address - in that case, a user should use
another Bitcoin address.

typescript/src/redemption.ts

@@ -412,11 +412,12 @@ export async function getRedemptionRequest(
 }
 
 /**
- * Finds the oldest active wallet that has enough BTC to handle a redemption request.
+ * Finds the oldest live wallet that has enough BTC to handle a redemption
+ * request.
  * @param amount The amount to be redeemed in satoshis.
- * @param redeemerOutputScript The redeemer output script the redeemed funds
- *        are supposed to be locked on. Must be un-prefixed and not prepended
- *        with length.
+ * @param redeemerOutputScript The redeemer output script the redeemed funds are
+ *        supposed to be locked on. Must be un-prefixed and not prepended with
+ *        length.
  * @param bitcoinNetwork Bitcoin network.
  * @param bridge The handle to the Bridge on-chain contract.
  * @param bitcoinClient Bitcoin client used to interact with the network.
@@ -441,6 +442,7 @@ export async function findWalletForRedemption(
       }
     | undefined = undefined
   let maxAmount = BigNumber.from(0)
+  let liveWalletsCounter = 0
 
   for (const wallet of wallets) {
     const { walletPublicKeyHash } = wallet
@@ -456,6 +458,7 @@ export async function findWalletForRedemption(
       )
       continue
     }
+    liveWalletsCounter++
 
     // Wallet must have a main UTXO that can be determined.
     const mainUtxo = await determineWalletMainUtxo(
@@ -511,6 +514,18 @@ export async function findWalletForRedemption(
     )
   }
 
+  if (liveWalletsCounter === 0) {
+    throw new Error("Currently, there are no live wallets in the network.")
+  }
+
+  // Cover a corner case when the user requested redemption for all live wallets
+  // in the network using the same Bitcoin address.
+  if (!walletData && liveWalletsCounter > 0 && maxAmount.eq(0)) {
+    throw new Error(
+      "All live wallets in the network have the pending redemption for a given Bitcoin address. Please use another Bitcoin address."
+    )
+  }
+
   if (!walletData)
     throw new Error(
       `Could not find a wallet with enough funds. Maximum redemption amount is ${maxAmount} Satoshi.`

typescript/test/redemption.test.ts

@@ -1468,7 +1468,7 @@ describe("Redemption", () => {
               bitcoinClient
             )
           ).to.be.rejectedWith(
-            "Could not find a wallet with enough funds. Maximum redemption amount is 0 Satoshi."
+            "Currently, there are no live wallets in the network."
           )
         })
       }
@@ -1676,6 +1676,61 @@ describe("Redemption", () => {
           })
         }
       )
+
+      context(
+        "when all active wallets has pending redemption for a given Bitcoin address",
+        () => {
+          const amount: BigNumber = BigNumber.from("1000000") // 0.01 BTC
+          const redeemerOutputScript =
+            findWalletForRedemptionData.pendingRedemption.redeemerOutputScript
+
+          beforeEach(async () => {
+            const walletPublicKeyHash =
+              findWalletForRedemptionData.walletWithPendingRedemption.event
+                .walletPublicKeyHash
+
+            const pendingRedemptions = new Map<
+              BigNumberish,
+              RedemptionRequest
+            >()
+
+            const pendingRedemption1 = MockBridge.buildRedemptionKey(
+              walletPublicKeyHash.toString(),
+              redeemerOutputScript
+            )
+
+            const pendingRedemption2 = MockBridge.buildRedemptionKey(
+              findWalletForRedemptionData.liveWallet.event.walletPublicKeyHash.toString(),
+              redeemerOutputScript
+            )
+
+            pendingRedemptions.set(
+              pendingRedemption1,
+              findWalletForRedemptionData.pendingRedemption
+            )
+
+            pendingRedemptions.set(
+              pendingRedemption2,
+              findWalletForRedemptionData.pendingRedemption
+            )
+            bridge.setPendingRedemptions(pendingRedemptions)
+          })
+
+          it("should throw an error", async () => {
+            await expect(
+              findWalletForRedemption(
+                amount,
+                redeemerOutputScript,
+                BitcoinNetwork.Testnet,
+                bridge,
+                bitcoinClient
+              )
+            ).to.be.rejectedWith(
+              "All live wallets in the network have the pending redemption for a given Bitcoin address. Please use another Bitcoin address."
+            )
+          })
+        }
+      )
     })
   })
 })