Unit Testing using jest

Author: learning-zone

js-unit-test-examples/jest/package.json

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+{
+  "name": "js-unit-test-examples-jest",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "jest"
+  },
+  "author": "",
+  "license": "Unlicense",
+  "devDependencies": {
+    "jest": "^18.1.0"
+  },
+  "jest": {
+    "collectCoverage": true,
+    "collectCoverageFrom": ["src/**/*.js"]
+  }
+}

js-unit-test-examples/jest/src/index.js

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+module.exports = function () {
+  this.add = function (a, b) {
+    return a + b;
+  };
+
+  this.multiply = function (a, b) {
+    return a * b;
+  };
+
+  this.fibonacci = function (length) {
+    var sequence = [0, 1];
+    for (var i = 2; i <= length; ++i) {
+      sequence[i] = sequence[i - 1] + sequence[i - 2];
+    }
+    return sequence;
+  };
+};

js-unit-test-examples/jest/test/index.test.js

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+const MathLib = require('../src');
+
+describe('MathLib', () => {
+  describe('add', () => {
+    it('adds two numbers together', () => {
+      const mathLib = new MathLib();
+      const result = mathLib.add(1, 2);
+      expect(result).toBe(3);
+    });
+  });
+
+  describe('multiply', () => {
+    it('multiply two numbers', () => {
+      const mathLib = new MathLib();
+      const result = mathLib.multiply(3, 3);
+      expect(result).toBe(9);
+    });
+  });
+
+  describe('fibonacci', () => {
+    it('generates a valid fibonacci sequence', () => {
+      const mathLib = new MathLib();
+      const result = mathLib.fibonacci(12);
+      expect(result[12]).toBe(144);
+    });
+  });
+});