bank-account added

exercises/practice/bank-account/.docs/instructions.md

@@ -0,0 +1,12 @@
+# Instructions
+
+Simulate a bank account supporting opening/closing, withdrawals, and deposits of money.
+Watch out for concurrent transactions!
+
+A bank account can be accessed in multiple ways.
+Clients can make deposits and withdrawals using the internet, mobile phones, etc.
+Shops can charge against the account.
+
+Create an account that can be accessed from multiple threads/processes (terminology depends on your programming language).
+
+It should be possible to close an account; operations against a closed account must fail.

exercises/practice/bank-account/.eslintignore

@@ -0,0 +1,13 @@
+!.meta
+
+# Protected or generated
+.git
+.vscode
+
+# When using npm
+node_modules/*
+
+# Configuration files
+.eslintrc.cjs
+babel.config.cjs
+jest.config.cjs

exercises/practice/bank-account/.eslintrc.cjs

@@ -0,0 +1,38 @@
+module.exports = {
+  root: true,
+  parserOptions: {
+    tsconfigRootDir: __dirname,
+    project: ['./tsconfig.json'],
+  },
+  overrides: [
+    // Student provided files
+    {
+      files: ['*.ts'],
+      excludedFiles: ['.meta/proof.ci.ts', '.meta/exemplar.ts', '*.test.ts'],
+      extends: '@exercism/eslint-config-typescript',
+    },
+    // Exercism given tests
+    {
+      files: ['*.test.ts'],
+      excludedFiles: ['custom.test.ts'],
+      env: {
+        jest: true,
+      },
+      extends: '@exercism/eslint-config-typescript/maintainers',
+    },
+    // Student provided tests
+    {
+      files: ['custom.test.ts'],
+      env: {
+        jest: true,
+      },
+      extends: '@exercism/eslint-config-typescript',
+    },
+    // Exercism provided files
+    {
+      files: ['.meta/proof.ci.ts', '.meta/exemplar.ts', '*.test.ts'],
+      excludedFiles: ['custom.test.ts'],
+      extends: '@exercism/eslint-config-typescript/maintainers',
+    },
+  ],
+}

exercises/practice/bank-account/.meta/config.json

@@ -0,0 +1,17 @@
+{
+  "authors": [
+    "therealowenrees"
+  ],
+  "files": {
+    "solution": [
+      "bank-account.ts"
+    ],
+    "test": [
+      "bank-account.test.ts"
+    ],
+    "example": [
+      ".meta/proof.ci.ts"
+    ]
+  },
+  "blurb": "Simulate a bank account supporting opening/closing, withdraws, and deposits of money. Watch out for concurrent transactions!"
+}

exercises/practice/bank-account/.meta/proof.ci.ts

@@ -0,0 +1,42 @@
+export class ValueError extends Error {
+  constructor() {
+    super('Bank account error')
+  }
+}
+
+export class BankAccount {
+  private _isOpen: boolean
+  private _balance: number
+
+  constructor() {
+    this._isOpen = false
+    this._balance = 0
+  }
+
+  open(): void {
+    if (this._isOpen) throw new ValueError()
+    this._isOpen = true
+  }
+
+  close(): void {
+    if (!this._isOpen) throw new ValueError()
+    this._isOpen = false
+    this._balance = 0
+  }
+
+  deposit(amount: number): void {
+    if (!this._isOpen || amount < 0) throw new ValueError()
+    this._balance += amount
+  }
+
+  withdraw(amount: number): void {
+    if (!this._isOpen || amount < 0 || amount > this._balance)
+      throw new ValueError()
+    this._balance -= amount
+  }
+
+  get balance(): number {
+    if (!this._isOpen) throw new ValueError()
+    return this._balance
+  }
+}

exercises/practice/bank-account/.meta/solutions/bank-account.ts

@@ -0,0 +1,41 @@
+export class ValueError extends Error {
+  constructor() {
+    super('Bank account error');
+  }
+}
+
+export class BankAccount {
+  private _isOpen: boolean
+  private _balance: number
+
+  constructor() {
+    this._isOpen = false
+    this._balance = 0
+  }
+
+  open(): void {
+    if (this._isOpen) throw new ValueError
+    this._isOpen = true
+  }
+
+  close(): void {
+    if (!this._isOpen) throw new ValueError
+    this._isOpen = false
+    this._balance = 0
+  }
+
+  deposit(amount: number): void {
+    if (!this._isOpen || amount < 0) throw new ValueError
+    this._balance += amount
+  }
+
+  withdraw(amount: number): void {
+    if (!this._isOpen || amount < 0 || amount > this._balance) throw new ValueError
+    this._balance -= amount
+  }
+
+  get balance(): number {
+    if (!this._isOpen) throw new ValueError
+    return this._balance
+  }
+}

exercises/practice/bank-account/.meta/tests.toml

@@ -0,0 +1,61 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[983a1528-4ceb-45e5-8257-8ce01aceb5ed]
+description = "Newly opened account has zero balance"
+
+[e88d4ec3-c6bf-4752-8e59-5046c44e3ba7]
+description = "Single deposit"
+
+[3d9147d4-63f4-4844-8d2b-1fee2e9a2a0d]
+description = "Multiple deposits"
+
+[08f1af07-27ae-4b38-aa19-770bde558064]
+description = "Withdraw once"
+
+[6f6d242f-8c31-4ac6-8995-a90d42cad59f]
+description = "Withdraw twice"
+
+[45161c94-a094-4c77-9cec-998b70429bda]
+description = "Can do multiple operations sequentially"
+
+[f9facfaa-d824-486e-8381-48832c4bbffd]
+description = "Cannot check balance of closed account"
+
+[7a65ba52-e35c-4fd2-8159-bda2bde6e59c]
+description = "Cannot deposit into closed account"
+
+[a0a1835d-faae-4ad4-a6f3-1fcc2121380b]
+description = "Cannot deposit into unopened account"
+
+[570dfaa5-0532-4c1f-a7d3-0f65c3265608]
+description = "Cannot withdraw from closed account"
+
+[c396d233-1c49-4272-98dc-7f502dbb9470]
+description = "Cannot close an account that was not opened"
+
+[c06f534f-bdc2-4a02-a388-1063400684de]
+description = "Cannot open an already opened account"
+
+[0722d404-6116-4f92-ba3b-da7f88f1669c]
+description = "Reopened account does not retain balance"
+
+[ec42245f-9361-4341-8231-a22e8d19c52f]
+description = "Cannot withdraw more than deposited"
+
+[4f381ef8-10ef-4507-8e1d-0631ecc8ee72]
+description = "Cannot withdraw negative"
+
+[d45df9ea-1db0-47f3-b18c-d365db49d938]
+description = "Cannot deposit negative"
+
+[ba0c1e0b-0f00-416f-8097-a7dfc97871ff]
+description = "Can handle concurrent transactions"

exercises/practice/bank-account/.yarnrc.yml

@@ -0,0 +1 @@
+yarnPath: .yarn/releases/yarn-3.6.4.cjs

exercises/practice/bank-account/babel.config.cjs

@@ -0,0 +1,4 @@
+module.exports = {
+  presets: ['@exercism/babel-preset-typescript'],
+  plugins: [],
+}

exercises/practice/bank-account/bank-account.test.ts

@@ -0,0 +1,125 @@
+import { BankAccount, ValueError } from './bank-account'
+
+describe('Bank Account', () => {
+  test('newly opened account has zero balance', () => {
+    const account = new BankAccount()
+    account.open()
+    expect(account.balance).toEqual(0)
+  })
+
+  xit('can deposit money', () => {
+    const account = new BankAccount()
+    account.open()
+    account.deposit(100)
+    expect(account.balance).toEqual(100)
+  })
+
+  xit('can deposit money sequentially', () => {
+    const account = new BankAccount()
+    account.open()
+    account.deposit(100)
+    account.deposit(50)
+    expect(account.balance).toEqual(150)
+  })
+
+  xit('can withdraw money', () => {
+    const account = new BankAccount()
+    account.open()
+    account.deposit(100)
+    account.withdraw(50)
+    expect(account.balance).toEqual(50)
+  })
+
+  xit('can withdraw money sequentially', () => {
+    const account = new BankAccount()
+    account.open()
+    account.deposit(100)
+    account.withdraw(20)
+    account.withdraw(80)
+    expect(account.balance).toEqual(0)
+  })
+
+  xit('checking balance of closed account throws error', () => {
+    const account = new BankAccount()
+    account.open()
+    account.close()
+    expect(() => account.balance).toThrow(ValueError)
+  })
+
+  xit('deposit into closed account throws error', () => {
+    const account = new BankAccount()
+    account.open()
+    account.close()
+    expect(() => {
+      account.deposit(50)
+    }).toThrow(ValueError)
+  })
+
+  xit('withdraw from closed account throws error', () => {
+    const account = new BankAccount()
+    account.open()
+    account.close()
+    expect(() => {
+      account.withdraw(50)
+    }).toThrow(ValueError)
+  })
+
+  xit('close already closed account throws error', () => {
+    const account = new BankAccount()
+    expect(() => {
+      account.close()
+    }).toThrow(ValueError)
+  })
+
+  xit('open already opened account throws error', () => {
+    const account = new BankAccount()
+    account.open()
+    expect(() => {
+      account.open()
+    }).toThrow(ValueError)
+  })
+
+  xit('reopened account does not retain balance', () => {
+    const account = new BankAccount()
+    account.open()
+    account.deposit(50)
+    account.close()
+    account.open()
+    expect(account.balance).toEqual(0)
+  })
+
+  xit('cannot withdraw more than deposited', () => {
+    const account = new BankAccount()
+    account.open()
+    account.deposit(25)
+    expect(() => {
+      account.withdraw(50)
+    }).toThrow(ValueError)
+  })
+
+  xit('cannot withdraw negative amount', () => {
+    const account = new BankAccount()
+    account.open()
+    account.deposit(100)
+    expect(() => {
+      account.withdraw(-50)
+    }).toThrow(ValueError)
+  })
+
+  xit('cannot deposit negative amount', () => {
+    const account = new BankAccount()
+    account.open()
+    expect(() => {
+      account.deposit(-50)
+    }).toThrow(ValueError)
+  })
+
+  xit('changing balance directly throws error', () => {
+    const account = new BankAccount()
+    account.open()
+    expect(() => {
+      account.balance = 100
+    }).toThrow(Error)
+  })
+})
+