[backend][nodejs] Return random choice from server

backend/nodejs/app.js

@@ -1,11 +1,11 @@
 const http = require('http');
-
+const randomDecision = require("./random-decision")
 const port = 3000;
 
 const server = http.createServer((request, response) => {
     response.statusCode = 200;
     response.setHeader('Content-Type', 'text/plain');
-    response.end('Hello World');
+    response.end(randomDecision.getRandomChoice().toString());
 });
 
 server.listen(port, () => {

backend/nodejs/package-lock.json

@@ -521,6 +521,14 @@
       "integrity": "sha512-q0M/9eZHzmr0AulXyPwNfZjtwZ/RBZlbN3K3CErVrk50T2ASYI7Bye0EvekFY3IP1Nt2DHu0re+V2ZHIpMkuWg==",
       "dev": true
     },
+    "random": {
+      "version": "3.0.3",
+      "resolved": "https://registry.npmjs.org/random/-/random-3.0.3.tgz",
+      "integrity": "sha512-Ppz8eI5oYbzC0dQKW3oSFFtyKnh7B1kN1kD7s6J545/aq+R1+YcqQEDJ5AZ0di3wYWbFV9otf5MaHJAhYH56Fw==",
+      "requires": {
+        "seedrandom": "^3.0.5"
+      }
+    },
     "randombytes": {
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/randombytes/-/randombytes-2.1.0.tgz",
@@ -551,6 +559,11 @@
       "integrity": "sha512-rp3So07KcdmmKbGvgaNxQSJr7bGVSVk5S9Eq1F+ppbRo70+YeaDxkw5Dd8NPN+GD6bjnYm2VuPuCXmpuYvmCXQ==",
       "dev": true
     },
+    "seedrandom": {
+      "version": "3.0.5",
+      "resolved": "https://registry.npmjs.org/seedrandom/-/seedrandom-3.0.5.tgz",
+      "integrity": "sha512-8OwmbklUNzwezjGInmZ+2clQmExQPvomqjL7LFqOYqtmuxRgQYqOD3mHaU+MvZn5FLUeVxVfQjwLZW/n/JFuqg=="
+    },
     "serialize-javascript": {
       "version": "5.0.1",
       "resolved": "https://registry.npmjs.org/serialize-javascript/-/serialize-javascript-5.0.1.tgz",
@@ -560,6 +573,54 @@
         "randombytes": "^2.1.0"
       }
     },
+    "should": {
+      "version": "13.2.3",
+      "resolved": "https://registry.npmjs.org/should/-/should-13.2.3.tgz",
+      "integrity": "sha512-ggLesLtu2xp+ZxI+ysJTmNjh2U0TsC+rQ/pfED9bUZZ4DKefP27D+7YJVVTvKsmjLpIi9jAa7itwDGkDDmt1GQ==",
+      "requires": {
+        "should-equal": "^2.0.0",
+        "should-format": "^3.0.3",
+        "should-type": "^1.4.0",
+        "should-type-adaptors": "^1.0.1",
+        "should-util": "^1.0.0"
+      }
+    },
+    "should-equal": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/should-equal/-/should-equal-2.0.0.tgz",
+      "integrity": "sha512-ZP36TMrK9euEuWQYBig9W55WPC7uo37qzAEmbjHz4gfyuXrEUgF8cUvQVO+w+d3OMfPvSRQJ22lSm8MQJ43LTA==",
+      "requires": {
+        "should-type": "^1.4.0"
+      }
+    },
+    "should-format": {
+      "version": "3.0.3",
+      "resolved": "https://registry.npmjs.org/should-format/-/should-format-3.0.3.tgz",
+      "integrity": "sha1-m/yPdPo5IFxT04w01xcwPidxJPE=",
+      "requires": {
+        "should-type": "^1.3.0",
+        "should-type-adaptors": "^1.0.1"
+      }
+    },
+    "should-type": {
+      "version": "1.4.0",
+      "resolved": "https://registry.npmjs.org/should-type/-/should-type-1.4.0.tgz",
+      "integrity": "sha1-B1bYzoRt/QmEOmlHcZ36DUz/XPM="
+    },
+    "should-type-adaptors": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/should-type-adaptors/-/should-type-adaptors-1.1.0.tgz",
+      "integrity": "sha512-JA4hdoLnN+kebEp2Vs8eBe9g7uy0zbRo+RMcU0EsNy+R+k049Ki+N5tT5Jagst2g7EAja+euFuoXFCa8vIklfA==",
+      "requires": {
+        "should-type": "^1.3.0",
+        "should-util": "^1.0.0"
+      }
+    },
+    "should-util": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/should-util/-/should-util-1.0.1.tgz",
+      "integrity": "sha512-oXF8tfxx5cDk8r2kYqlkUJzZpDBqVY/II2WhvU0n9Y3XYvAYRmeaf1PvvIvTgPnv4KJ+ES5M0PyDq5Jp+Ygy2g=="
+    },
     "string-width": {
       "version": "2.1.1",
       "resolved": "https://registry.npmjs.org/string-width/-/string-width-2.1.1.tgz",

backend/nodejs/package.json

@@ -11,5 +11,9 @@
   "license": "ISC",
   "devDependencies": {
     "mocha": "^8.3.2"
+  },
+  "dependencies": {
+    "random": "^3.0.3",
+    "should": "^13.2.3"
   }
 }

backend/nodejs/random-decision.js

@@ -0,0 +1,23 @@
+const random = require('random');
+
+class Choice {
+    constructor(name) {
+        this.name = name;
+    }
+
+    toString() {
+        return this.name;
+    }
+}
+
+const choices = [
+    new Choice('A'),
+    new Choice('B'),
+    new Choice('C')
+];
+
+exports.getRandomChoice = () => {
+    return choices[random.int(0, choices.length - 1)];
+}
+
+exports.choices = choices;

backend/nodejs/test/random-decision.js

@@ -0,0 +1,38 @@
+const assert = require('assert');
+const should = require('should');
+const randomDecision = require('../random-decision');
+
+describe('randomDecision', function () {
+    describe('#getRandomChoice', function () {
+        it(`should return one of available choices`, function () {
+            randomDecision.getRandomChoice().should.equalOneOf(randomDecision.choices);
+        });
+
+        it('should return the first choice sometimes', function () {
+            const expectedChoice = randomDecision.choices[0];
+            const selectedChoices = new Set();
+            for (let i = 0; i <= 1000; i++) {
+                const decision = randomDecision.getRandomChoice();
+                selectedChoices.add(decision);
+                if (decision === expectedChoice) {
+                    should.ok(decision, 'First choice was found once');
+                    return;
+                }
+            }
+            should.fail(selectedChoices, expectedChoice, 'First choice was never selected');
+        })
+        it('should return the last choice sometimes', function () {
+            const expectedChoice = randomDecision.choices[randomDecision.choices.length - 1];
+            const selectedChoices = new Set();
+            for (let i = 0; i <= 1000; i++) {
+                const decision = randomDecision.getRandomChoice();
+                selectedChoices.add(decision);
+                if (decision === expectedChoice) {
+                    should.ok(decision, 'Last choice was found once');
+                    return;
+                }
+            }
+            should.fail(selectedChoices, expectedChoice, 'Last choice was never selected');
+        })
+    })
+})

backend/nodejs/test/test.js

@@ -1,9 +0,0 @@
-var assert = require('assert');
-
-describe('Array', function () {
-    describe('#indexOf', function () {
-        it('should return -1 when the value is not present', function () {
-            assert.strictEqual([1, 2, 3].indexOf(4), -1);
-        });
-    })
-})