Add Typescript

typescript/ExtractAndOverrideFactoryMethod/deps.ts

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+export * as testing from 'https://deno.land/std@0.103.0/testing/asserts.ts';

typescript/ExtractAndOverrideFactoryMethod/index.test.ts

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+import { testing } from './deps.ts';
+import { App } from './index.ts';
+
+const { assertEquals } = testing;
+
+namespace RunTime {
+  export class PaymentGateway extends App.PaymentGateway {
+    public getLedger(): App.PaymentLedger {
+      return this.ledger;
+    }
+  }
+
+  export class PaymentGatewayTest {
+    public regression(): void {
+      const paymentGateway = new RunTime.PaymentGateway();
+      paymentGateway.makePayment('Me', 'You', 100, 'AUD');
+      const lodgedPayment = paymentGateway.getLedger().getPayment(0);
+
+      Deno.test('must return the payer name', (): void => {
+        assertEquals('Me', lodgedPayment.getPayer().getName());
+      });
+      Deno.test('must return the payee name', (): void => {
+        assertEquals('You', lodgedPayment.getPayee().getName());
+      });
+      Deno.test('must return the cents', (): void => {
+        assertEquals(100, lodgedPayment.getCents());
+      });
+    }
+  }
+}
+
+new RunTime.PaymentGatewayTest().regression();

typescript/ExtractAndOverrideFactoryMethod/index.ts

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+export namespace App {
+  class User {
+    private name: string;
+
+    constructor(name: string) {
+      this.name = name;
+    }
+
+    public getName() {
+      return this.name;
+    }
+  }
+
+  class UserRepository {
+    constructor() {}
+
+    public findByName(name: string) {
+      return new User(name);
+    }
+  }
+
+  class Payment {
+    private payer: User;
+    private payee: User;
+    private cents: number;
+
+    constructor(payer: User, payee: User, cents: number) {
+      this.payer = payer;
+      this.payee = payee;
+      this.cents = cents;
+    }
+
+    public getPayer(): User {
+      return this.payer;
+    }
+
+    public getPayee(): User {
+      return this.payee;
+    }
+
+    public getCents(): number {
+      return this.cents;
+    }
+  }
+
+  export class PaymentLedger {
+    private ledger: Payment[] = [];
+
+    constructor(dBConnection: Library.DBConnection) {}
+
+    public lodge(payment: Payment) {
+      this.ledger.push(payment);
+    }
+
+    public getPayment(paymentNumber: number): Payment {
+      return this.ledger[paymentNumber];
+    }
+  }
+
+  export class PaymentGateway {
+    private dbConnection: Library.DBConnection;
+    private repository: UserRepository;
+    public ledger: PaymentLedger;
+
+    /**
+     * This hard-coded initialization inside the constructor is the issue we're trying to solve
+     *
+     * @memberof PaymentGateway
+     */
+    constructor() {
+      this.dbConnection = new Library.DBConnection();
+      this.repository = new UserRepository();
+      this.ledger = new PaymentLedger(this.dbConnection);
+    }
+
+    /**
+     * Challenge:
+     * - Add a currency argument to this method with an appropriate test.
+     * - Do not use the UserRepository or PaymentLedger to test this class (that would
+     *   take far too long to setup!!)
+     * - The currency in use before this change was AUD.
+     *
+     * @param {string} fromName
+     * @param {string} toName
+     * @param {number} cents
+     * @memberof PaymentGateway
+     */
+    public makePayment(fromName: string, toName: string, cents: number): void {
+      const fromUser = this.repository.findByName(fromName);
+      const toUser = this.repository.findByName(toName);
+      const payment = new Payment(fromUser, toUser, cents);
+      this.ledger.lodge(payment);
+    }
+  }
+}
+
+namespace Library {
+  export class DBConnection {
+    public executeCommand(query: string): void {
+      // ...
+    }
+    public executeQuery(query: string): any[] {
+      // ...
+      return [];
+    }
+  }
+}

typescript/README.md

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+# Extract And Override Factory Method
+
+## Install
+
+The only requirement needed to run the code is [Dene](https://deno.land/)
+
+Homebrew (Mac):
+
+```bash
+$ brew install deno
+```
+
+Other options can be found at [here](https://deno.land/manual@v1.12.1/getting_started/installation)
+
+## Run the test
+
+```bash
+# Run all tests in the current directory and all sub-directories
+deno test
+
+# Run all tests in the ExtractAndOverrideFactoryMethod directory
+deno test ./ExtractAndOverrideFactoryMethod/
+
+# Run just my_test.ts
+deno test my_test.ts
+```