✨ 【第6章 テスト不足に気づいたら】 重複コード排除のため Money クラスに equals メソッドを追加する

src/__tests__/dollar.test.ts

@@ -6,15 +6,3 @@ test('times', () => {
   expect(five.times(2)).toEqual(new Dollar(10));
   expect(five.times(3)).toEqual(new Dollar(15));
 });
-
-test('equals', () => {
-  expect(new Dollar(5).equals(new Dollar(5))).toBeTruthy();
-  expect(new Dollar(5).equals(new Dollar(6))).toBeFalsy();
-});
-
-test('null equals', () => {
-  const five = new Dollar(5);
-  const ten = five.times(2);
-
-  expect(ten.equals(null)).toBeFalsy();
-});

src/__tests__/franc.test.ts

@@ -6,15 +6,3 @@ test('times', () => {
   expect(five.times(2)).toEqual(new Franc(10));
   expect(five.times(3)).toEqual(new Franc(15));
 });
-
-test('equals', () => {
-  expect(new Franc(5).equals(new Franc(5))).toBeTruthy();
-  expect(new Franc(5).equals(new Franc(6))).toBeFalsy();
-});
-
-test('null equals', () => {
-  const five = new Franc(5);
-  const ten = five.times(2);
-
-  expect(ten.equals(null)).toBeFalsy();
-});

src/__tests__/money.test.ts

@@ -0,0 +1,12 @@
+import { Money } from '../money';
+
+test('equals', () => {
+  expect(new Money(5).equals(new Money(5))).toBeTruthy();
+  expect(new Money(5).equals(new Money(6))).toBeFalsy();
+});
+
+test('null equals', () => {
+  const five = new Money(5);
+
+  expect(five.equals(null)).toBeFalsy();
+});

src/dollar.ts

@@ -1,19 +1,11 @@
 import { Money } from "./money";
 
 export class Dollar extends Money {
-  constructor(amount: number) { 
+  constructor(amount: number) {
     super(amount);
   }
 
   times(multiplier: number) {
     return new Dollar(this.amount * multiplier)
   }
-
-  equals(dollar: Dollar | null) {
-    if (dollar === null) {
-        return false;
-    }
-
-    return this.amount === dollar.amount
-  }
 }

src/franc.ts

@@ -1,19 +1,11 @@
 import { Money } from "./money";
 
-export class Franc extends Money  {
+export class Franc extends Money {
   constructor(amount: number) {
     super(amount);
-　}
+  }
 
   times(multiplier: number) {
     return new Franc(this.amount * multiplier)
   }
-
-  equals(franc: Franc | null) {
-    if (franc === null) {
-        return false;
-    }
-
-    return this.amount === franc.amount
-  }
 }

src/money.ts

@@ -1,4 +1,12 @@
 export class Money {
   constructor(protected readonly amount: number) {
   }
+
+  equals(money: Money | null) {
+    if (money === null) {
+        return false;
+    }
+
+    return this.amount === money.amount
+  }
 }