created app.js & app.test.js

.gitignore

@@ -0,0 +1,2 @@
+node_modules
+package-lock.json

package.json

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+{
+  "name": "software-dev-course-unit-testing",
+  "version": "1.0.0",
+  "description": "This is the README.md file! I, as the presenter, will fill it with content!",
+  "main": "index.js",
+  "scripts": {
+    "test": "jest"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/LaunchCodeEducation/software-dev-course-unit-testing.git"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "bugs": {
+    "url": "https://github.com/LaunchCodeEducation/software-dev-course-unit-testing/issues"
+  },
+  "homepage": "https://github.com/LaunchCodeEducation/software-dev-course-unit-testing#readme",
+  "devDependencies": {
+    "jest": "^30.1.3"
+  }
+}

product-inventory/app.js

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+function calculateDiscount(price, discountRate) {
+    if (typeof price !== 'number' || typeof discountRate !== 'number') return null;
+    if (discountRate < 0 || discountRate > 1) return null;
+    // TODO: Implement logic
+    let amount = price - (price * discountRate);
+    return amount;
+}
+
+function filterProducts(products, callback) {
+    if (!Array.isArray(products) || typeof callback !== 'function') return [];
+    // TODO: Implement filtering logic
+    let filteredProducts = products.filter(callback);
+    return filteredProducts;
+}
+
+
+
+function sortInventory(inventory, key) {
+    if (!Array.isArray(inventory) || typeof key !== 'string') return [];
+    // TODO: Implement sorting logic
+    inventory.sort(function (a, b) {
+        let keyA = a[key];
+        let keyB = b[key];
+
+        if (keyA < keyB) return -1;
+        if (keyA > keyB) return 1;
+        return 0;
+    })
+    return inventory;
+}
+
+module.exports = {
+    calculateDiscount,
+    filterProducts,
+    sortInventory
+};

product-inventory/test/app.test.js

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+const store = require('../app.js');
+
+describe("The calculateDiscount () function", () => {
+    test('should return the discounted amount', () => {
+        expect(store.calculateDiscount(100, 0.1)).toEqual(90);
+    })
+    test('should return null for invalid discount rate', () => {
+        expect(store.calculateDiscount(100, 10)).toEqual(null);
+    })
+    test('should return original price when discount rate is 0', () => {
+        expect(store.calculateDiscount(100, 0)).toEqual(100);
+    });
+});
+
+describe("The filterProducts () function", () => {
+    test('should return a filtered array', () => {
+
+        let initArray = ["Pizza", "Burger", "Fries"];
+        let solutionArray = ["Pizza", "Fries"];
+        expect(store.filterProducts(initArray, function (entry) {
+            return entry !== "Burger";
+        })).toEqual(solutionArray);
+    })
+    test('should return an empty string for invalid function', () => {
+
+        let initArray = ["Pizza", "Burger", "Fries"];
+
+        expect(store.filterProducts(initArray, null)).toEqual([]);
+    })
+    test('should return an empty string for removing everything', () => {
+        let initArray = ["Pizza", "Burger", "Fries"];
+
+        expect(store.filterProducts(initArray, function () { return false })).toEqual([]);
+    })
+})
+
+describe("The sortInventor () function", () => {
+    test('should return a sorted array', () => {
+
+        let initArray = [
+            { "num": 30 },
+            { "num": 20 },
+            { "num": 32 },
+            { "num": 10 },
+        ];
+        let solutionArray = [
+            { "num": 10 },
+            { "num": 20 },
+            { "num": 30 },
+            { "num": 32 },
+        ];
+        expect(store.sortInventory(initArray, "num")).toEqual(solutionArray);
+    })
+    test('should return an empty array for no key', () => {
+
+        let initArray = [
+            { "num": 30 },
+            { "num": 20 },
+            { "num": 32 },
+            { "num": 10 },
+        ];
+
+        expect(store.sortInventory(initArray, null)).toEqual([]);
+    })
+    test('should return the same array for no change in sorting', () => {
+
+        let initArray = [
+            { "num": 30 },
+            { "num": 20 },
+            { "num": 60 },
+            { "num": 10 },
+        ];
+
+        expect(store.sortInventory(initArray, "key")).toEqual(initArray);
+    })
+})
+