Third task

README.md

@@ -36,12 +36,14 @@ It also includes config linters for `JavaScript` in the `.github` directory.
 
 📌 **Key Features:**
 - Each task has its own unit & tester file
-- All tasks have separate test suite with description text
+- All tasks are in separate test group with description text
 - Function `stringLength` returns a number for the input string length
 - Any string length outside the range of `(1 - 10)` throws an error `Value out of range!`
 - Three test cases are implemented in `stringLength.test.js` for checking valid & invalid input
-- Function `reverseString` return the input string with characters in reverse order
+- Function `reverseString` returns the input string with characters in reverse order
 - One test case was done for `reverseString` function in `reverseString.test.js`
+- Object `calculator` contains four functions (`add` / `subtract` / `multiply` / `divide`)
+- Each function inside the `calculator` object has three test cases grouped together
 
 <p align="right"><a href="#title">back to top</a></p>
 

testers/calculator.test.js

@@ -0,0 +1,48 @@
+const calculator = require('../units/calculator.js');
+
+describe('Calculator object functions test', () => {
+  describe('Testing the add function', () => {
+    test('Adding 3 + 2 should equal 5', () => {
+      expect(calculator.add(3, 2)).toEqual(5);
+    });
+    test('Adding 1000000000 + 1000000000 should equal 2000000000', () => {
+      expect(calculator.add(1000000000, 1000000000)).toEqual(2000000000);
+    });
+    test('Adding (-3) + (-2) should equal -5', () => {
+      expect(calculator.add(-3, -2)).toEqual(-5);
+    });
+  });
+  describe('Testing the subtract function', () => {
+    test('Subtracting 3 - 2 should equal 1', () => {
+      expect(calculator.subtract(3, 2)).toEqual(1);
+    });
+    test('Subtracting 1000000000 - 1000000000 should equal 0', () => {
+      expect(calculator.subtract(1000000000, 1000000000)).toEqual(0);
+    });
+    test('Subtracting (-3) - (-2) should equal -5', () => {
+      expect(calculator.subtract(-3, -2)).toEqual(-1);
+    });
+  });
+  describe('Testing the multiply function', () => {
+    test('Multiplying 3 * 2 should equal 6', () => {
+      expect(calculator.multiply(3, 2)).toEqual(6);
+    });
+    test('Multiplying 1000000000 * 1000000000 should equal 1000000000000000000', () => {
+      expect(calculator.multiply(1000000000, 1000000000)).toEqual(1000000000000000000);
+    });
+    test('Multiplying (-3) * (-2) should equal 6', () => {
+      expect(calculator.multiply(-3, -2)).toEqual(6);
+    });
+  });
+  describe('Testing the divide function', () => {
+    test('Dividing 3 / 2 should equal 1.5', () => {
+      expect(calculator.divide(3, 2)).toEqual(1.5);
+    });
+    test('Dividing 1000000000 / 1000000000 should equal 1', () => {
+      expect(calculator.divide(1000000000, 1000000000)).toEqual(1);
+    });
+    test('Dividing (-3) / (-2) should equal 1.5', () => {
+      expect(calculator.divide(-3, -2)).toEqual(1.5);
+    });
+  });
+});

testers/stringLength.test.js

@@ -1,13 +1,13 @@
 const stringLength = require('../units/stringLength.js');
 
 describe('Testing stringLength function', () => {
-  test('Testing length of "word" string which in range and equals 4', () => {
+  test('The "word" string is in range and equals 4', () => {
     expect(stringLength('word')).toEqual(4);
   });
-  test('Testing length of empty sting "" which is out of range and throws an error', () => {
+  test('An empty string "" is out of range and throws an error', () => {
     expect(() => stringLength('')).toThrow('Value out of range!');
   });
-  test('Testing length of "optimization" string which is out of range and throws an error', () => {
+  test('Word "optimization" is out of range and throws an error', () => {
     expect(() => stringLength('optimization')).toThrow('Value out of range!');
   });
 });

units/calculator.js

@@ -0,0 +1,6 @@
+module.exports = {
+  add: (x, y) => x + y,
+  subtract: (x, y) => x - y,
+  multiply: (x, y) => x * y,
+  divide: (x, y) => x / y,
+};