1 files changed, 70 insertions, 0 deletions
diff --git a/spec/frontend/merge_request_tabs_spec.js b/spec/frontend/merge_request_tabs_spec.js
index 69ff5e47689..6d434d7e654 100644
--- a/spec/frontend/merge_request_tabs_spec.js
+++ b/spec/frontend/merge_request_tabs_spec.js
@@ -5,6 +5,7 @@ import initMrPage from 'helpers/init_vue_mr_page_helper';
 import { stubPerformanceWebAPI } from 'helpers/performance';
 import axios from '~/lib/utils/axios_utils';
 import MergeRequestTabs from '~/merge_request_tabs';
+import Diff from '~/diff';
 import '~/lib/utils/common_utils';
 import '~/lib/utils/url_utility';
 
@@ -389,4 +390,73 @@ describe('MergeRequestTabs', () => {
       });
     });
   });
+
+  describe('tabs <-> diff interactions', () => {
+    beforeEach(() => {
+      jest.spyOn(testContext.class, 'loadDiff').mockImplementation(() => {});
+    });
+
+    describe('switchViewType', () => {
+      it('marks the class as having not loaded diffs already', () => {
+        testContext.class.diffsLoaded = true;
+
+        testContext.class.switchViewType({});
+
+        expect(testContext.class.diffsLoaded).toBe(false);
+      });
+
+      it('reloads the diffs', () => {
+        testContext.class.switchViewType({ source: 'a new url' });
+
+        expect(testContext.class.loadDiff).toHaveBeenCalledWith({
+          endpoint: 'a new url',
+          strip: false,
+        });
+      });
+    });
+
+    describe('createDiff', () => {
+      it("creates a Diff if there isn't one", () => {
+        expect(testContext.class.diffsClass).toBe(null);
+
+        testContext.class.createDiff();
+
+        expect(testContext.class.diffsClass).toBeInstanceOf(Diff);
+      });
+
+      it("doesn't create a Diff if one already exists", () => {
+        testContext.class.diffsClass = 'truthy';
+
+        testContext.class.createDiff();
+
+        expect(testContext.class.diffsClass).toBe('truthy');
+      });
+
+      it('sets the available MR Tabs event hub to the new Diff', () => {
+        expect(testContext.class.diffsClass).toBe(null);
+
+        testContext.class.createDiff();
+
+        expect(testContext.class.diffsClass.mrHub).toBe(testContext.class.eventHub);
+      });
+    });
+
+    describe('setHubToDiff', () => {
+      it('sets the MR Tabs event hub to the child Diff', () => {
+        testContext.class.diffsClass = {};
+
+        testContext.class.setHubToDiff();
+
+        expect(testContext.class.diffsClass.mrHub).toBe(testContext.class.eventHub);
+      });
+
+      it('does not fatal if theres no child Diff', () => {
+        testContext.class.diffsClass = null;
+
+        expect(() => {
+          testContext.class.setHubToDiff();
+        }).not.toThrow();
+      });
+    });
+  });
 });