Increase unit test coverage: unit tests for Electrum.getTransaction (#…

…747)

#Refs: #714.
This PR adds a missing unit test for `Electrum.getTransaction`.

typescript/test/lib/electrum.test.ts

@@ -16,9 +16,12 @@ import {
   testnetTxHashes,
   testnetUTXO,
 } from "../data/electrum"
-import { expect } from "chai"
+import chai, { expect } from "chai"
+import chaiAsPromised from "chai-as-promised"
 import https from "https"
 
+chai.use(chaiAsPromised)
+
 const BLOCKSTREAM_TESTNET_API_URL = "https://blockstream.info/testnet/api"
 
 const testnetCredentials: ElectrumCredentials[] = [
@@ -145,7 +148,16 @@ describe("Electrum", () => {
             expect(result).to.be.eql(testnetTransaction)
           })
 
-          // TODO: Add case when transaction doesn't exist.
+          it("should throw for unknown transaction hash", async function () {
+            // Set custom timeout as the electrum server attempts to execute the
+            // function several times.
+            this.timeout(100000)
+            const unknownTransaction = BitcoinTxHash.from(
+              "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+            )
+            await expect(electrumClient.getTransaction(unknownTransaction)).to
+              .be.rejected
+          })
         })
 
         describe("getRawTransaction", () => {