introduction of chai-as-promised, modifed count down should fail test…

… to demonstrate testing of expected reverts
Dhaiwat10 · Feb 27, 2021 · c627690 · c627690
1 parent a420815
commit c627690
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Showing 3 changed files with 24 additions and 3 deletions.
diff --git a/package-lock.json b/package-lock.json
diff --git a/package.json b/package.json
@@ -26,9 +26,11 @@
     "@nomiclabs/hardhat-waffle": "^2.0.1",
     "@typechain/ethers-v5": "^5.0.0",
     "@types/chai": "^4.2.15",
+    "@types/chai-as-promised": "^7.1.3",
     "@types/mocha": "^8.2.0",
     "@types/node": "^14.14.28",
     "chai": "^4.3.0",
+    "chai-as-promised": "^7.1.1",
     "dotenv": "^8.2.0",
     "ethereum-waffle": "^3.2.2",
     "ethers": "^5.0.31",

diff --git a/test/counter.ts b/test/counter.ts
@@ -1,9 +1,11 @@
 import { ethers } from "hardhat";
 import chai from "chai";
+import chaiAsPromised from "chai-as-promised";
 import { solidity } from "ethereum-waffle";
 import { Counter__factory, Counter } from "../typechain";
 
 chai.use(solidity);
+chai.use(chaiAsPromised);
 const { expect } = chai;
 
 describe("Counter", () => {
@@ -38,9 +40,8 @@ describe("Counter", () => {
 
   describe("count down", async () => {
     // 5
-    it("should fail", async () => {
-      // this test will fail
-      await counter.countDown();
+    it("should fail due to underflow exception", () => {
+      return expect(counter.countDown()).to.eventually.be.rejectedWith(Error, 'Uint256 underflow');
     });
 
     it("should count down", async () => {