Basic testing

src/01-simple-tests/index.test.ts

@@ -1,32 +1,63 @@
-// Uncomment the code below and write your tests
-// import { simpleCalculator, Action } from './index';
+import { simpleCalculator, Action } from './index';
 
 describe('simpleCalculator tests', () => {
   test('should add two numbers', () => {
-    // Write your test here
+    expect(simpleCalculator({ a: 7, b: 6, action: Action.Add })).toBe(13);
+    expect(simpleCalculator({ a: -7, b: 6, action: Action.Add })).toBe(-1);
+    expect(simpleCalculator({ a: 2, b: 2, action: Action.Add })).toBe(4);
   });
 
   test('should subtract two numbers', () => {
-    // Write your test here
+    expect(simpleCalculator({ a: 7, b: 6, action: Action.Subtract })).toBe(1);
+    expect(simpleCalculator({ a: -7, b: 6, action: Action.Subtract })).toBe(
+      -13,
+    );
+    expect(simpleCalculator({ a: 2, b: 2, action: Action.Subtract })).toBe(0);
   });
 
   test('should multiply two numbers', () => {
-    // Write your test here
+    expect(simpleCalculator({ a: 7, b: 6, action: Action.Multiply })).toBe(42);
+    expect(simpleCalculator({ a: -7, b: 6, action: Action.Multiply })).toBe(
+      -42,
+    );
+    expect(simpleCalculator({ a: 0, b: 2, action: Action.Multiply })).toBe(0);
   });
 
   test('should divide two numbers', () => {
-    // Write your test here
+    expect(simpleCalculator({ a: 15, b: 3, action: Action.Divide })).toBe(5);
+    expect(simpleCalculator({ a: -15, b: 3, action: Action.Divide })).toBe(-5);
+    expect(simpleCalculator({ a: 0, b: 2, action: Action.Divide })).toBe(0);
+    expect(simpleCalculator({ a: 2, b: 0, action: Action.Divide })).toBe(
+      Infinity,
+    );
   });
 
   test('should exponentiate two numbers', () => {
-    // Write your test here
+    expect(simpleCalculator({ a: 2, b: 3, action: Action.Exponentiate })).toBe(
+      8,
+    );
+    expect(simpleCalculator({ a: -2, b: 3, action: Action.Exponentiate })).toBe(
+      -8,
+    );
+    expect(simpleCalculator({ a: 2, b: -3, action: Action.Exponentiate })).toBe(
+      0.125,
+    );
+    expect(simpleCalculator({ a: 0, b: 3, action: Action.Exponentiate })).toBe(
+      0,
+    );
   });
 
   test('should return null for invalid action', () => {
-    // Write your test here
+    expect(simpleCalculator({ a: 7, b: 6, action: '%' })).toBeNull();
   });
 
   test('should return null for invalid arguments', () => {
-    // Write your test here
+    expect(simpleCalculator({ a: '7', b: 6, action: Action.Add })).toBeNull();
+    expect(
+      simpleCalculator({ a: 7, b: '6', action: Action.Subtract }),
+    ).toBeNull();
+    expect(
+      simpleCalculator({ a: null, b: 6, action: Action.Multiply }),
+    ).toBeNull();
   });
 });

src/02-table-tests/index.test.ts

@@ -1,17 +1,36 @@
-// Uncomment the code below and write your tests
-/* import {  simpleCalculator, Action } from './index';
+import { simpleCalculator, Action } from './index';
 
 const testCases = [
-    { a: 1, b: 2, action: Action.Add, expected: 3 },
-    { a: 2, b: 2, action: Action.Add, expected: 4 },
-    { a: 3, b: 2, action: Action.Add, expected: 5 },
-    // continue cases for other actions    
-]; */
+  { a: 1, b: 2, action: Action.Add, expected: 3 },
+  { a: 2, b: 2, action: Action.Add, expected: 4 },
+  { a: 3, b: 2, action: Action.Add, expected: 5 },
+  { a: 7, b: 6, action: Action.Add, expected: 13 },
+  { a: -7, b: 6, action: Action.Add, expected: -1 },
+  { a: 7, b: 6, action: Action.Subtract, expected: 1 },
+  { a: -7, b: 6, action: Action.Subtract, expected: -13 },
+  { a: 2, b: 2, action: Action.Subtract, expected: 0 },
+  { a: 7, b: 6, action: Action.Multiply, expected: 42 },
+  { a: -7, b: 6, action: Action.Multiply, expected: -42 },
+  { a: 0, b: 2, action: Action.Multiply, expected: 0 },
+  { a: 15, b: 3, action: Action.Divide, expected: 5 },
+  { a: -15, b: 3, action: Action.Divide, expected: -5 },
+  { a: 0, b: 2, action: Action.Divide, expected: 0 },
+  { a: 2, b: 0, action: Action.Divide, expected: Infinity },
+  { a: 2, b: 3, action: Action.Exponentiate, expected: 8 },
+  { a: -2, b: 3, action: Action.Exponentiate, expected: -8 },
+  { a: 2, b: -3, action: Action.Exponentiate, expected: 0.125 },
+  { a: 0, b: 3, action: Action.Exponentiate, expected: 0 },
+  { a: 7, b: 6, action: '%', expected: null },
+  { a: '7', b: 6, action: Action.Add, expected: null },
+  { a: 7, b: '6', action: Action.Add, expected: null },
+  { a: null, b: 6, action: Action.Add, expected: null },
+];
 
 describe('simpleCalculator', () => {
-  // This test case is just to run this test suite, remove it when you write your own tests
-  test('should blah-blah', () => {
-    expect(true).toBe(true);
-  });
-  // Consider to use Jest table tests API to test all cases above
+  test.each(testCases)(
+    'should return $expected for a=$a, b=$b, action=$action',
+    ({ a, b, action, expected }) => {
+      expect(simpleCalculator({ a, b, action })).toBe(expected);
+    },
+  );
 });

src/03-error-handling-async/index.test.ts

@@ -1,30 +1,37 @@
-// Uncomment the code below and write your tests
-// import { throwError, throwCustomError, resolveValue, MyAwesomeError, rejectCustomError } from './index';
+import {
+  throwError,
+  throwCustomError,
+  resolveValue,
+  MyAwesomeError,
+  rejectCustomError,
+} from './index';
 
 describe('resolveValue', () => {
   test('should resolve provided value', async () => {
-    // Write your test here
+    const value = 'Hello, world!';
+    await expect(resolveValue(value)).resolves.toBe(value);
   });
 });
 
 describe('throwError', () => {
   test('should throw error with provided message', () => {
-    // Write your test here
+    const message = 'Error message';
+    expect(() => throwError(message)).toThrow(message);
   });
 
   test('should throw error with default message if message is not provided', () => {
-    // Write your test here
+    expect(() => throwError()).toThrow('Oops!');
   });
 });
 
 describe('throwCustomError', () => {
   test('should throw custom error', () => {
-    // Write your test here
+    expect(() => throwCustomError()).toThrow(MyAwesomeError);
   });
 });
 
 describe('rejectCustomError', () => {
   test('should reject custom error', async () => {
-    // Write your test here
+    await expect(rejectCustomError()).rejects.toThrow(MyAwesomeError);
   });
 });

src/04-test-class/index.test.ts

@@ -1,44 +1,104 @@
-// Uncomment the code below and write your tests
-// import { getBankAccount } from '.';
+import {
+  getBankAccount,
+  InsufficientFundsError,
+  TransferFailedError,
+  SynchronizationFailedError,
+} from '.';
+import { random } from 'lodash';
+
+jest.mock('lodash', () => ({
+  random: jest.fn(),
+}));
+
+const initialBalance = 1000;
+const balance = 100;
 
 describe('BankAccount', () => {
   test('should create account with initial balance', () => {
-    // Write your test here
+    const account = getBankAccount(initialBalance);
+
+    expect(account.getBalance()).toBe(initialBalance);
   });
 
   test('should throw InsufficientFundsError error when withdrawing more than balance', () => {
-    // Write your test here
+    const account = getBankAccount(initialBalance);
+
+    expect(() => account.withdraw(10000)).toThrow(InsufficientFundsError);
   });
 
   test('should throw error when transferring more than balance', () => {
-    // Write your test here
+    const account1 = getBankAccount(initialBalance);
+    const account2 = getBankAccount(initialBalance);
+
+    expect(() => account1.transfer(10000, account2)).toThrow(
+      InsufficientFundsError,
+    );
   });
 
   test('should throw error when transferring to the same account', () => {
-    // Write your test here
+    const account = getBankAccount(initialBalance);
+
+    expect(() => account.transfer(100, account)).toThrow(TransferFailedError);
   });
 
   test('should deposit money', () => {
-    // Write your test here
+    const account = getBankAccount(initialBalance);
+    const depositAmount = 100;
+
+    account.deposit(depositAmount);
+    expect(account.getBalance()).toBe(initialBalance + depositAmount);
   });
 
   test('should withdraw money', () => {
-    // Write your test here
+    const account = getBankAccount(initialBalance);
+    const withdrawAmount = 100;
+
+    account.withdraw(withdrawAmount);
+    expect(account.getBalance()).toBe(initialBalance - withdrawAmount);
   });
 
   test('should transfer money', () => {
-    // Write your test here
+    const account1 = getBankAccount(initialBalance);
+    const account2 = getBankAccount(initialBalance);
+    const transferAmount = 100;
+
+    account1.transfer(transferAmount, account2);
+    expect(account1.getBalance()).toBe(initialBalance - transferAmount);
+    expect(account2.getBalance()).toBe(initialBalance + transferAmount);
   });
 
   test('fetchBalance should return number in case if request did not failed', async () => {
-    // Write your tests here
+    const account = getBankAccount(initialBalance);
+    const balance = 100;
+    const requestSucceeded = 1;
+
+    (random as jest.Mock)
+      .mockReturnValueOnce(balance)
+      .mockReturnValueOnce(requestSucceeded);
+    await expect(account.fetchBalance()).resolves.toBe(balance);
   });
 
   test('should set new balance if fetchBalance returned number', async () => {
-    // Write your tests here
+    const account = getBankAccount(initialBalance);
+    const requestSucceeded = 1;
+
+    (random as jest.Mock)
+      .mockReturnValueOnce(balance)
+      .mockReturnValueOnce(requestSucceeded);
+    await account.synchronizeBalance();
+    expect(account.getBalance()).toBe(balance);
   });
 
   test('should throw SynchronizationFailedError if fetchBalance returned null', async () => {
-    // Write your tests here
+    const account = getBankAccount(initialBalance);
+    const requestFailed = 0;
+
+    (random as jest.Mock)
+      .mockReturnValueOnce(balance)
+      .mockReturnValueOnce(requestFailed);
+    await expect(account.synchronizeBalance()).rejects.toThrow(
+      SynchronizationFailedError,
+    );
+    expect(account.getBalance()).toBe(initialBalance);
   });
 });

src/05-partial-mocking/index.test.ts

@@ -1,20 +1,34 @@
-// Uncomment the code below and write your tests
-// import { mockOne, mockTwo, mockThree, unmockedFunction } from './index';
+import { mockOne, mockTwo, mockThree, unmockedFunction } from './index';
 
 jest.mock('./index', () => {
-  // const originalModule = jest.requireActual<typeof import('./index')>('./index');
+  const originalModule =
+    jest.requireActual<typeof import('./index')>('./index');
+
+  return {
+    ...originalModule,
+    mockOne: jest.fn(),
+    mockTwo: jest.fn(),
+    mockThree: jest.fn(),
+  };
 });
 
 describe('partial mocking', () => {
-  afterAll(() => {
-    jest.unmock('./index');
-  });
-
   test('mockOne, mockTwo, mockThree should not log into console', () => {
-    // Write your test here
+    const consoleSpy = jest.spyOn(console, 'log');
+    mockOne();
+    mockTwo();
+    mockThree();
+    expect(mockOne).toHaveBeenCalled();
+    expect(mockTwo).toHaveBeenCalled();
+    expect(mockThree).toHaveBeenCalled();
+    expect(consoleSpy).not.toHaveBeenCalled();
+    consoleSpy.mockRestore();
   });
 
   test('unmockedFunction should log into console', () => {
-    // Write your test here
+    const consoleSpy = jest.spyOn(console, 'log');
+    unmockedFunction();
+    expect(consoleSpy).toHaveBeenCalledWith('I am not mocked');
+    consoleSpy.mockRestore();
   });
 });