doing step 4 demo notes

step2-04/demo/src/index.spec.ts

@@ -1,13 +1,20 @@
 import { square } from '.';
+import { multiply } from './multiply';
+
+// Mocked here by jest for the entire test module file
+jest.mock('./multiply');
 
 describe('jest example', () => {
   beforeEach(() => {
     jest.resetModules();
   });
 
-  it('should be able to give the square of two numbers', () => {
-    console.log('test');
-    expect(square(5)).toBe(25);
+  it('should be passing in the multiple two of the same number', () => {
+    square(5);
+
+    // .toBeCalledTimes() and .toBeCalledWith() only work on mocks - we mocked the multiply function from the
+    expect(multiply).toBeCalledTimes(1);
+    expect(multiply).toBeCalledWith(5, 5);
   });
 
   it('should increment counter', () => {

step2-04/demo/src/index.ts

@@ -1,3 +1,5 @@
+import { multiply } from './multiply';
+
 let counter = 0;
 
 export function getCount() {
@@ -13,5 +15,5 @@ export function decrement() {
 }
 
 export function square(x: number) {
-  return x * x;
+  return multiply(x, x);
 }

step2-04/demo/src/multiply.ts

@@ -0,0 +1,3 @@
+export function multiply(x: number, y: number) {
+  return x * y;
+}

step2-04/demo/src/store/index.ts

@@ -1,14 +0,0 @@
-export type FilterTypes = 'all' | 'active' | 'completed';
-
-export interface TodoItem {
-  label: string;
-  completed: boolean;
-}
-
-export interface Store {
-  todos: {
-    [id: string]: TodoItem;
-  };
-
-  filter: FilterTypes;
-}