Basic Testing

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

@@ -1,32 +1,36 @@
 // 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: 1, b: 2, action: Action.Add })).toBe(3);
   });
 
   test('should subtract two numbers', () => {
-    // Write your test here
+    expect(simpleCalculator({ a: 5, b: 3, action: Action.Subtract })).toBe(2);
   });
 
   test('should multiply two numbers', () => {
-    // Write your test here
+    expect(simpleCalculator({ a: 4, b: 6, action: Action.Multiply })).toBe(24);
   });
 
   test('should divide two numbers', () => {
-    // Write your test here
+    expect(simpleCalculator({ a: 72, b: 8, action: Action.Divide })).toBe(9);
   });
 
   test('should exponentiate two numbers', () => {
-    // Write your test here
+    expect(simpleCalculator({ a: 2, b: 5, action: Action.Exponentiate })).toBe(
+      32,
+    );
   });
 
   test('should return null for invalid action', () => {
-    // Write your test here
+    expect(simpleCalculator({ a: 2, b: 5, action: 'string' })).toBe(null);
   });
 
   test('should return null for invalid arguments', () => {
-    // Write your test here
+    expect(simpleCalculator({ a: 'string', b: {}, action: Action.Add })).toBe(
+      null,
+    );
   });
 });

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

@@ -1,17 +1,33 @@
 // 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: 9, b: 2, action: Action.Subtract, expected: 7 },
+  { a: 8, b: 2, action: Action.Subtract, expected: 6 },
+  { a: 7, b: 2, action: Action.Subtract, expected: 5 },
+
+  { a: 42, b: 7, action: Action.Divide, expected: 6 },
+  { a: 81, b: 9, action: Action.Divide, expected: 9 },
+  { a: 15, b: 3, action: Action.Divide, expected: 5 },
+
+  { a: 4, b: 7, action: Action.Multiply, expected: 28 },
+  { a: 2, b: 5, action: Action.Multiply, expected: 10 },
+  { a: 12, b: 12, action: Action.Multiply, expected: 144 },
+
+  { a: 2, b: 3, action: Action.Exponentiate, expected: 8 },
+  { a: 3, b: 4, action: Action.Exponentiate, expected: 81 },
+  { a: 4, b: 5, action: Action.Exponentiate, expected: 1024 },
+];
 
 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 when $a $action $b',
+    ({ a, b, action, expected }) => {
+      expect(simpleCalculator({ a, b, action })).toBe(expected);
+    },
+  );
 });

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

@@ -1,30 +1,36 @@
 // 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
+    await expect(resolveValue(5)).resolves.toBe(5);
   });
 });
 
 describe('throwError', () => {
   test('should throw error with provided message', () => {
-    // Write your test here
+    expect(() => throwError('Error message')).toThrow('Error 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 +1,62 @@
 // Uncomment the code below and write your tests
-// import { getBankAccount } from '.';
+import { getBankAccount } from '.';
 
 describe('BankAccount', () => {
   test('should create account with initial balance', () => {
-    // Write your test here
+    expect(getBankAccount(100).getBalance()).toBe(100);
   });
 
   test('should throw InsufficientFundsError error when withdrawing more than balance', () => {
-    // Write your test here
+    expect(getBankAccount(100).getBalance()).toBe(100);
   });
 
   test('should throw error when transferring more than balance', () => {
-    // Write your test here
+    expect(() => getBankAccount(100).withdraw(200)).toThrow();
   });
 
   test('should throw error when transferring to the same account', () => {
-    // Write your test here
+    const account = getBankAccount(100);
+    expect(() => account.transfer(200, account)).toThrow();
   });
 
   test('should deposit money', () => {
-    // Write your test here
+    expect(getBankAccount(100).deposit(200).getBalance()).toBe(300);
   });
 
   test('should withdraw money', () => {
-    // Write your test here
+    expect(getBankAccount(300).withdraw(170).getBalance()).toBe(130);
   });
 
   test('should transfer money', () => {
-    // Write your test here
+    const firstAccount = getBankAccount(300);
+    const secondAccount = getBankAccount(100);
+
+    expect(firstAccount.transfer(150, secondAccount).getBalance()).toBe(150);
+    expect(secondAccount.getBalance()).toBe(250);
   });
 
   test('fetchBalance should return number in case if request did not failed', async () => {
-    // Write your tests here
+    const balance = await getBankAccount(100).fetchBalance();
+
+    if (balance === null) {
+      expect(balance).toBeNull();
+    } else {
+      expect(typeof balance).toBe('number');
+      expect(balance).toBeGreaterThanOrEqual(0);
+      expect(balance).toBeLessThanOrEqual(100);
+    }
   });
 
   test('should set new balance if fetchBalance returned number', async () => {
-    // Write your tests here
+    const account = getBankAccount(100);
+    jest.spyOn(account, 'fetchBalance').mockResolvedValue(200);
+    await account.synchronizeBalance();
+    expect(account.getBalance()).toBe(200);
   });
 
   test('should throw SynchronizationFailedError if fetchBalance returned null', async () => {
-    // Write your tests here
+    const account = getBankAccount(100);
+    jest.spyOn(account, 'fetchBalance').mockResolvedValue(null);
+    expect(account.synchronizeBalance).rejects.toThrow();
   });
 });

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

@@ -1,8 +1,16 @@
 // 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', () => {
@@ -11,10 +19,20 @@ describe('partial mocking', () => {
   });
 
   test('mockOne, mockTwo, mockThree should not log into console', () => {
-    // Write your test here
+    const spyLog = jest.spyOn(console, 'log');
+
+    mockOne();
+    mockTwo();
+    mockThree();
+
+    expect(spyLog).not.toHaveBeenCalled();
   });
 
   test('unmockedFunction should log into console', () => {
-    // Write your test here
+    const spyLog = jest.spyOn(console, 'log');
+
+    unmockedFunction();
+
+    expect(spyLog).toHaveBeenCalledWith('I am not mocked');
   });
 });

src/06-mocking-node-api/index.test.ts

@@ -1,5 +1,8 @@
 // Uncomment the code below and write your tests
-// import { readFileAsynchronously, doStuffByTimeout, doStuffByInterval } from '.';
+import { readFileAsynchronously, doStuffByTimeout, doStuffByInterval } from '.';
+import path from 'path';
+import fs from 'fs';
+import fsPromises from 'fs/promises';
 
 describe('doStuffByTimeout', () => {
   beforeAll(() => {
@@ -11,11 +14,22 @@ describe('doStuffByTimeout', () => {
   });
 
   test('should set timeout with provided callback and timeout', () => {
-    // Write your test here
+    const spyTimeout = jest.spyOn(global, 'setTimeout');
+    const cb = jest.fn();
+    const timeout = 1000;
+
+    doStuffByTimeout(cb, timeout);
+    expect(spyTimeout).toHaveBeenCalledWith(cb, timeout);
   });
 
   test('should call callback only after timeout', () => {
-    // Write your test here
+    const cb = jest.fn();
+    const timeout = 1000;
+
+    doStuffByTimeout(cb, timeout);
+    expect(cb).not.toHaveBeenCalled();
+    jest.advanceTimersByTime(timeout);
+    expect(cb).toHaveBeenCalled();
   });
 });
 
@@ -29,24 +43,50 @@ describe('doStuffByInterval', () => {
   });
 
   test('should set interval with provided callback and timeout', () => {
-    // Write your test here
+    const spyInterval = jest.spyOn(global, 'setInterval');
+    const cb = jest.fn();
+    const interval = 1000;
+
+    doStuffByInterval(cb, interval);
+    expect(spyInterval).toHaveBeenCalledWith(cb, interval);
   });
 
   test('should call callback multiple times after multiple intervals', () => {
-    // Write your test here
+    const cb = jest.fn();
+    const interval = 1000;
+
+    doStuffByInterval(cb, interval);
+    expect(cb).not.toHaveBeenCalled();
+    jest.advanceTimersByTime(interval * 3);
+    expect(cb).toHaveBeenCalledTimes(3);
   });
 });
 
 describe('readFileAsynchronously', () => {
   test('should call join with pathToFile', async () => {
-    // Write your test here
+    const spyJoin = jest.spyOn(path, 'join');
+    const filePath = 'test';
+
+    await readFileAsynchronously(filePath);
+    expect(spyJoin).toHaveBeenCalledWith(__dirname, filePath);
   });
 
   test('should return null if file does not exist', async () => {
-    // Write your test here
+    jest.spyOn(fs, 'existsSync').mockReturnValue(false);
+    const filePath = 'test';
+    const result = await readFileAsynchronously(filePath);
+
+    expect(result).toBeNull();
   });
 
   test('should return file content if file exists', async () => {
-    // Write your test here
+    jest.spyOn(fs, 'existsSync').mockReturnValue(true);
+    const filePath = 'test';
+    const content = 'test';
+    const bufferContent = Buffer.from(content);
+
+    jest.spyOn(fsPromises, 'readFile').mockResolvedValue(bufferContent);
+    const result = await readFileAsynchronously(filePath);
+    expect(result).toBe(content);
   });
 });