Merge pull request #523 from MaoShizhong/repeat-string-builtin

02_repeatString: Add test preventing use of `String.prototype.repeat`

02_repeatString/repeatString.spec.js

@@ -13,6 +13,13 @@ describe('repeatString', () => {
   test.skip('repeats the string 0 times', () => {
     expect(repeatString('bye', 0)).toEqual('');
   });
+  test.skip('does not use the built-in String repeat method', () => {
+    /* Even though there is a built-in String repeat method,
+      in this exercise specifically, we want you to practise using loops */
+    jest.spyOn(String.prototype, 'repeat').mockName('Built-in String repeat method');
+    repeatString("don't use the built-in repeat method!", 1);
+    expect(String.prototype.repeat).not.toHaveBeenCalled();
+  });
   test.skip('returns ERROR with negative numbers', () => {
     expect(repeatString('goodbye', -1)).toEqual('ERROR');
   });

02_repeatString/solution/repeatString-solution.spec.js

@@ -13,6 +13,13 @@ describe('repeatString', () => {
   test('repeats the string 0 times', () => {
     expect(repeatString('bye', 0)).toEqual('');
   });
+  test('does not use the built-in String repeat method', () => {
+    /* Even though there is a built-in String repeat method,
+      in this exercise specifically, we want you to practise using loops */
+    jest.spyOn(String.prototype, 'repeat').mockName('Built-in String repeat method');
+    repeatString("don't use the built-in repeat method!", 1);
+    expect(String.prototype.repeat).not.toHaveBeenCalled();
+  });
   test('returns ERROR with negative numbers', () => {
     expect(repeatString('goodbye', -1)).toEqual('ERROR');
   });