Merge pull request #4061 from michaelduminy/master

Allow replacing of stories (again)

lib/core/src/client/preview/client_api.js

@@ -95,7 +95,7 @@ export default class ClientApi {
       }
 
       if (this._storyStore.hasStory(kind, storyName)) {
-        throw new Error(`Story of "${kind}" named "${storyName}" already exists`);
+        logger.warn(`Story of "${kind}" named "${storyName}" already exists`);
       }
 
       // Wrap the getStory function with each decorator. The first

lib/core/src/client/preview/client_api.test.js

@@ -344,4 +344,52 @@ describe('preview.client_api', () => {
       });
     });
   });
+
+  describe('storiesOf', () => {
+    describe('add', () => {
+      it('should replace stories when adding the same story', () => {
+        const stories = [jest.fn().mockReturnValue('story1'), jest.fn().mockReturnValue('story2')];
+        const api = new ClientAPI();
+        expect(api.getStorybook()).toEqual([]);
+
+        api.storiesOf('kind', module).add('story', stories[0]);
+        {
+          const book = api.getStorybook();
+          expect(book).toHaveLength(1);
+
+          const entry = book[0];
+          expect(entry.kind).toMatch('kind');
+          expect(entry.stories).toHaveLength(1);
+          expect(entry.stories[0].name).toBe('story');
+
+          // v3 returns the same function we passed in
+          if (jest.isMockFunction(entry.stories[0].render)) {
+            expect(entry.stories[0].render).toBe(stories[0]);
+          } else {
+            expect(entry.stories[0].render()).toBe('story1');
+          }
+        }
+
+        const warn = jest.spyOn(global.console, 'warn').mockImplementationOnce(jest.fn());
+        api.storiesOf('kind', module).add('story', stories[1]);
+        expect(warn).toHaveBeenCalled();
+        {
+          const book = api.getStorybook();
+          expect(book).toHaveLength(1);
+
+          const entry = book[0];
+          expect(entry.kind).toMatch('kind');
+          expect(entry.stories).toHaveLength(1);
+          expect(entry.stories[0].name).toBe('story');
+
+          // v3 returns the same function we passed in
+          if (jest.isMockFunction(entry.stories[0].render)) {
+            expect(entry.stories[0].render).toBe(stories[0]);
+          } else {
+            expect(entry.stories[0].render()).toBe('story2');
+          }
+        }
+      });
+    });
+  });
 });