Basic testing

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

@@ -1,32 +1,49 @@
-// 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
+    const input = { a: 3, b: 5, action: Action.Add };
+    const result = simpleCalculator(input);
+    expect(result).toBe(8);
   });
 
   test('should subtract two numbers', () => {
-    // Write your test here
+    const input = { a: 10, b: 4, action: Action.Subtract };
+    const result = simpleCalculator(input);
+    expect(result).toBe(6);
   });
 
   test('should multiply two numbers', () => {
-    // Write your test here
+    const input = { a: 6, b: 7, action: Action.Multiply };
+    const result = simpleCalculator(input);
+    expect(result).toBe(42);
   });
 
   test('should divide two numbers', () => {
-    // Write your test here
+    const input = { a: 20, b: 5, action: Action.Divide };
+    const result = simpleCalculator(input);
+    expect(result).toBe(4);
   });
 
   test('should exponentiate two numbers', () => {
-    // Write your test here
+    const input = { a: 2, b: 3, action: Action.Exponentiate };
+    const result = simpleCalculator(input);
+    expect(result).toBe(8);
   });
 
   test('should return null for invalid action', () => {
-    // Write your test here
+    const input = { a: 5, b: 10, action: 'invalid_action' };
+    const result = simpleCalculator(input);
+    expect(result).toBeNull();
   });
 
   test('should return null for invalid arguments', () => {
-    // Write your test here
+    const input1 = { a: 'string', b: 10, action: Action.Add };
+    const input2 = { a: 5, b: null, action: Action.Subtract };
+    const input3 = { a: 5, b: 10, action: 123 }; // invalid action type
+
+    expect(simpleCalculator(input1)).toBeNull();
+    expect(simpleCalculator(input2)).toBeNull();
+    expect(simpleCalculator(input3)).toBeNull();
   });
 });

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

@@ -1,17 +1,35 @@
-// 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: 5, b: 3, action: Action.Subtract, expected: 2 },
+  { a: 6, b: 2, action: Action.Subtract, expected: 4 },
+  { a: 3, b: 3, action: Action.Multiply, expected: 9 },
+  { a: 8, b: 2, action: Action.Multiply, expected: 16 },
+  { a: 10, b: 2, action: Action.Divide, expected: 5 },
+  { a: 9, b: 3, action: Action.Divide, expected: 3 },
+  { a: 2, b: 3, action: Action.Exponentiate, expected: 8 },
+  { a: 5, b: 2, action: Action.Exponentiate, expected: 25 },
+];
 
 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);
+  test.each(testCases)(
+    'should calculate $a $action $b to be $expected',
+    ({ a, b, action, expected }) => {
+      const result = simpleCalculator({ a, b, action });
+      expect(result).toBe(expected);
+    },
+  );
+
+  test('should return null for invalid action', () => {
+    const result = simpleCalculator({ a: 1, b: 2, action: 'invalid' });
+    expect(result).toBeNull();
+  });
+
+  test('should return null for invalid arguments', () => {
+    const result = simpleCalculator({ a: '1', b: 2, action: Action.Add });
+    expect(result).toBeNull();
   });
-  // Consider to use Jest table tests API to test all cases above
-});
+});

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

@@ -1,30 +1,44 @@
-// 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 = 'test';
+    const result = await resolveValue(value);
+    expect(result).toBe(value);
   });
 });
 
 describe('throwError', () => {
   test('should throw error with provided message', () => {
-    // Write your test here
+    const errorMessage = 'Custom error message';
+    expect(() => throwError(errorMessage)).toThrowError(errorMessage);
   });
 
   test('should throw error with default message if message is not provided', () => {
-    // Write your test here
+    expect(() => throwError()).toThrowError('Oops!');
   });
 });
 
 describe('throwCustomError', () => {
   test('should throw custom error', () => {
-    // Write your test here
+    expect(() => throwCustomError()).toThrowError(MyAwesomeError);
+    expect(() => throwCustomError()).toThrowError(
+      'This is my awesome custom error!',
+    );
   });
 });
 
 describe('rejectCustomError', () => {
   test('should reject custom error', async () => {
-    // Write your test here
+    await expect(rejectCustomError()).rejects.toThrowError(MyAwesomeError);
+    await expect(rejectCustomError()).rejects.toThrowError(
+      'This is my awesome custom error!',
+    );
   });
 });

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

@@ -1,44 +1,84 @@
-// Uncomment the code below and write your tests
-// import { getBankAccount } from '.';
+import {
+  getBankAccount,
+  InsufficientFundsError,
+  TransferFailedError,
+  SynchronizationFailedError,
+} from './index';
+import { random } from 'lodash';
+
+jest.mock('lodash', () => ({
+  random: jest.fn(),
+}));
 
 describe('BankAccount', () => {
   test('should create account with initial balance', () => {
-    // Write your test here
+    const account = getBankAccount(100);
+    expect(account.getBalance()).toBe(100);
   });
 
   test('should throw InsufficientFundsError error when withdrawing more than balance', () => {
-    // Write your test here
+    const account = getBankAccount(50);
+    expect(() => account.withdraw(100)).toThrow(InsufficientFundsError);
+    expect(() => account.withdraw(100)).toThrow(
+      'Insufficient funds: cannot withdraw more than 50',
+    );
   });
 
   test('should throw error when transferring more than balance', () => {
-    // Write your test here
+    const account1 = getBankAccount(50);
+    const account2 = getBankAccount(100);
+
+    expect(() => account1.transfer(100, account2)).toThrow(
+      InsufficientFundsError,
+    );
   });
 
   test('should throw error when transferring to the same account', () => {
-    // Write your test here
+    const account = getBankAccount(50);
+    expect(() => account.transfer(10, account)).toThrow(TransferFailedError);
+    expect(() => account.transfer(10, account)).toThrow('Transfer failed');
   });
 
   test('should deposit money', () => {
-    // Write your test here
+    const account = getBankAccount(50);
+    account.deposit(50);
+    expect(account.getBalance()).toBe(100);
   });
 
   test('should withdraw money', () => {
-    // Write your test here
+    const account = getBankAccount(100);
+    account.withdraw(50);
+    expect(account.getBalance()).toBe(50);
   });
 
   test('should transfer money', () => {
-    // Write your test here
+    const account1 = getBankAccount(100);
+    const account2 = getBankAccount(50);
+
+    account1.transfer(50, account2);
+    expect(account1.getBalance()).toBe(50);
+    expect(account2.getBalance()).toBe(100);
   });
 
-  test('fetchBalance should return number in case if request did not failed', async () => {
-    // Write your tests here
+  test('fetchBalance should return number in case request did not fail', async () => {
+    (random as jest.Mock).mockReturnValueOnce(75).mockReturnValueOnce(1);
+    const account = getBankAccount(100);
+    const balance = await account.fetchBalance();
+    expect(balance).toBe(75);
   });
 
   test('should set new balance if fetchBalance returned number', async () => {
-    // Write your tests here
+    (random as jest.Mock).mockReturnValueOnce(75).mockReturnValueOnce(1);
+    const account = getBankAccount(100);
+    await account.synchronizeBalance();
+    expect(account.getBalance()).toBe(75);
   });
 
   test('should throw SynchronizationFailedError if fetchBalance returned null', async () => {
-    // Write your tests here
+    (random as jest.Mock).mockReturnValueOnce(50).mockReturnValueOnce(0);
+    const account = getBankAccount(100);
+    await expect(account.synchronizeBalance()).rejects.toThrow(
+      SynchronizationFailedError,
+    );
   });
 });

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

@@ -1,8 +1,12 @@
-// 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');
+  return {
+    mockOne: jest.fn(),
+    mockTwo: jest.fn(),
+    mockThree: jest.fn(),
+    unmockedFunction: jest.requireActual('./index').unmockedFunction,
+  };
 });
 
 describe('partial mocking', () => {
@@ -11,10 +15,23 @@ describe('partial mocking', () => {
   });
 
   test('mockOne, mockTwo, mockThree should not log into console', () => {
-    // Write your test here
+    const consoleSpy = jest.spyOn(console, 'log');
+
+    mockOne();
+    mockTwo();
+    mockThree();
+
+    expect(consoleSpy).not.toHaveBeenCalledWith('foo');
+    expect(consoleSpy).not.toHaveBeenCalledWith('bar');
+    expect(consoleSpy).not.toHaveBeenCalledWith('baz');
+
+    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();
   });
 });