Remove Chai

Chai v5 is ESM-only which would be a really big migration. We're not
doing any complicated assertions in the tests here so I think it makes
sense to just switch to the built-in `assert` module. We get to drop a
dependency (just under 1MB) and I think assert is easier to understand
anyway.

package.json

@@ -30,7 +30,6 @@
     "@dotcom-tool-kit/mocha": "^4.0.1",
     "@dotcom-tool-kit/prettier": "^4.0.1",
     "@financial-times/eslint-config-next": "^7.1.0",
-    "chai": "^4.3.6",
     "dotcom-tool-kit": "^4.0.1",
     "mocha": "^10.0.0",
     "proxyquire": "^2.1.3",

test/aggregate.check.spec.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const expect = require('chai').expect;
+const assert = require('node:assert/strict');
 const config = require('./fixtures/config/aggregate').checks[2];
 const AggregateCheck = require('../src/checks/').aggregate;
 
@@ -34,7 +34,7 @@ describe('Aggregate Check', function () {
 			MockHealthChecks.checks[1].ok = true;
 			check.start();
 			setTimeout(function () {
-				expect(check.getStatus().ok).to.be.true;
+				assert.equal(check.getStatus().ok, true);
 				done();
 			});
 		});
@@ -44,7 +44,7 @@ describe('Aggregate Check', function () {
 			MockHealthChecks.checks[1].ok = false;
 			check.start();
 			setTimeout(function () {
-				expect(check.getStatus().ok).to.be.false;
+				assert.equal(check.getStatus().ok, false);
 				done();
 			});
 		});

test/cloudWatchAlarm.check.spec.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const expect = require('chai').expect;
+const assert = require('node:assert/strict');
 const configFixture = require('./fixtures/config/cloudWatchAlarmFixture')
 	.checks[0];
 const failedFixture = require('./fixtures/cloudWatchAlarmFailedResponse');
@@ -43,44 +43,43 @@ describe('CloudWatch Alarm Check', () => {
 		check.start();
 		await waitFor(10);
 		//
-		expect(cloudWatchSdkMock.CloudWatchClient.calledOnce).to.be.true;
-		expect(cloudWatchSdkMock.CloudWatchClient.calledWithNew()).to.be.true;
-		expect(cloudWatchSdkMock.DescribeAlarmsCommand.calledOnce).to.be.true;
-		expect(cloudWatchSdkMock.DescribeAlarmsCommand.calledWithNew()).to.be.true;
-		expect(cloudWatchClientMock.send.calledOnce).to.be.true;
+		assert.equal(cloudWatchSdkMock.CloudWatchClient.calledOnce, true);
+		assert.equal(cloudWatchSdkMock.CloudWatchClient.calledWithNew(), true);
+		assert.equal(cloudWatchSdkMock.DescribeAlarmsCommand.calledOnce, true);
+		assert.equal(cloudWatchSdkMock.DescribeAlarmsCommand.calledWithNew(), true);
+		assert.equal(cloudWatchClientMock.send.calledOnce, true);
 
 		const sendArgs = cloudWatchClientMock.send.lastCall.args[0];
-		expect(sendArgs).to.deep.equal(cloudWatchCommandMock);
+		assert.deepEqual(sendArgs, cloudWatchCommandMock);
 
 		const commandArgs =
 			cloudWatchSdkMock.DescribeAlarmsCommand.lastCall.args[0];
-		expect(commandArgs).to.have.property('AlarmNames');
-		expect(commandArgs.AlarmNames).to.be.an('Array');
-		expect(commandArgs.AlarmNames[0]).to.be.an('String');
-		expect(commandArgs.AlarmNames[0]).to.equal('test');
+		assert.ok(commandArgs.AlarmNames);
+		assert.ok(Array.isArray(commandArgs.AlarmNames));
+		assert.equal(commandArgs.AlarmNames[0], 'test');
 	});
 
 	it('Should pass if the current state of the given alarm is OK', async () => {
 		cloudWatchClientMock.send.returns(Promise.resolve(passedFixture));
 		check = new Check(configFixture);
 		check.start();
 		await waitFor(10);
-		expect(check.getStatus().ok).to.be.true;
+		assert.equal(check.getStatus().ok, true);
 	});
 
 	it('Should fail if the current state of the given alarm is ALARM', async () => {
 		cloudWatchClientMock.send.returns(Promise.resolve(failedFixture));
 		check = new Check(configFixture);
 		check.start();
 		await waitFor(10);
-		expect(check.getStatus().ok).to.be.false;
+		assert.equal(check.getStatus().ok, false);
 	});
 
 	it('Should fail if there is no data', async () => {
 		cloudWatchClientMock.send.returns(Promise.resolve(insufficentFixture));
 		check = new Check(configFixture);
 		check.start();
 		await waitFor(10);
-		expect(check.getStatus().ok).to.be.false;
+		assert.equal(check.getStatus().ok, false);
 	});
 });