Merge pull request #637 from bvotteler/fix-max-burnable-tokens-return…

…-zero

Fix: Return zero max burnable tokens when no liquidation vault exists

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@interlay/interbtc-api",
-  "version": "2.2.3",
+  "version": "2.2.4",
   "description": "JavaScript library to interact with interBTC",
   "main": "build/src/index.js",
   "typings": "build/src/index.d.ts",

src/parachain/redeem.ts

@@ -12,7 +12,7 @@ import {
     InterbtcPrimitivesRedeemRedeemRequest,
 } from "@polkadot/types/lookup";
 
-import { VaultsAPI } from "./vaults";
+import { NO_LIQUIDATION_VAULT_FOUND_REJECTION, VaultsAPI } from "./vaults";
 import {
     decodeBtcAddress,
     decodeFixedPointType,
@@ -27,7 +27,7 @@ import { allocateAmountsToVaults } from "../utils/issueRedeem";
 import { ElectrsAPI } from "../external";
 import { TransactionAPI } from "./transaction";
 import { OracleAPI } from "./oracle";
-import { CollateralCurrencyExt, ExtrinsicData, Redeem, WrappedCurrency } from "../types";
+import { CollateralCurrencyExt, ExtrinsicData, Redeem, SystemVaultExt, WrappedCurrency } from "../types";
 import { SystemAPI } from "./system";
 
 /**
@@ -332,7 +332,15 @@ export class DefaultRedeemAPI implements RedeemAPI {
     }
 
     async getMaxBurnableTokens(collateralCurrency: CollateralCurrencyExt): Promise<MonetaryAmount<WrappedCurrency>> {
-        const liquidationVault = await this.vaultsAPI.getLiquidationVault(collateralCurrency);
+        const liquidationVault: SystemVaultExt | null = await this.vaultsAPI.getLiquidationVault(collateralCurrency)
+            // method rejects if no vault was found, wrap as null    
+            .catch((reason) => (reason === NO_LIQUIDATION_VAULT_FOUND_REJECTION) ? null : Promise.reject(reason));
+
+        if (liquidationVault === null) {
+            // no liquidation vault exists, therefore, no burnable tokens)
+            return BitcoinAmount.zero();
+        }
+
         // This should never be below 0, but still...
         const burnableTokens = liquidationVault.issuedTokens.sub(liquidationVault.toBeRedeemedTokens);
         if (burnableTokens.lte(BitcoinAmount.zero())) {

src/parachain/vaults.ts

@@ -410,6 +410,8 @@ export interface VaultsAPI {
     ): Promise<Big | undefined>;
 }
 
+export const NO_LIQUIDATION_VAULT_FOUND_REJECTION = "No liquidation vault found";
+
 export class DefaultVaultsAPI implements VaultsAPI {
     constructor(
         private api: ApiPromise,
@@ -657,8 +659,9 @@ export class DefaultVaultsAPI implements VaultsAPI {
         const vaultCurrencyPair = newVaultCurrencyPair(this.api, collateralCurrency, this.wrappedCurrency);
         const liquidationVault = await this.api.query.vaultRegistry.liquidationVault(vaultCurrencyPair);
         if (!liquidationVault.isSome) {
-            return Promise.reject("System vault could not be fetched");
+            return Promise.reject(NO_LIQUIDATION_VAULT_FOUND_REJECTION);
         }
+
         return await parseSystemVault(
             this.api,
             liquidationVault.value as VaultRegistrySystemVault,

test/unit/parachain/redeem.test.ts

@@ -4,6 +4,7 @@ import { DefaultRedeemAPI, DefaultVaultsAPI, VaultsAPI } from "../../../src";
 import { newMonetaryAmount } from "../../../src/utils";
 import { ExchangeRate, KBtc, Kintsugi } from "@interlay/monetary-js";
 import Big from "big.js";
+import { NO_LIQUIDATION_VAULT_FOUND_REJECTION } from "../../../src/parachain/vaults";
 
 describe("DefaultRedeemAPI", () => {
     let redeemApi: DefaultRedeemAPI;
@@ -95,4 +96,26 @@ describe("DefaultRedeemAPI", () => {
             );
         });
     });
+
+    describe("getMaxBurnableTokens", () => {
+        afterEach(() => {
+            sinon.restore();
+            sinon.reset();
+        });
+
+        it("should return zero if getLiquidationVault rejects with no liquidation vault message", async () => {
+            // stub internal call to return no liquidation vault
+            stubbedVaultsApi.getLiquidationVault.withArgs(sinon.match.any).returns(Promise.reject(NO_LIQUIDATION_VAULT_FOUND_REJECTION));
+
+            const actualValue = await redeemApi.getMaxBurnableTokens(Kintsugi);
+            expect(actualValue.toBig().toNumber()).to.be.eq(0);
+        });
+
+        it("should propagate rejection if getLiquidationVault rejects with other message", async () => {
+            // stub internal call to return no liquidation vault
+            stubbedVaultsApi.getLiquidationVault.withArgs(sinon.match.any).returns(Promise.reject("foobar happened here"));
+
+            await expect(redeemApi.getMaxBurnableTokens(Kintsugi)).to.be.rejectedWith("foobar happened here");
+        });
+    });
 });