Collapse diff tree is only one file is present

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/53139

2 files changed, 65 insertions, 0 deletions

diff --git a/spec/javascripts/diffs/components/app_spec.js b/spec/javascripts/diffs/components/app_spec.js
index d81c433cca6..8d7c52a2876 100644
--- a/spec/javascripts/diffs/components/app_spec.js
+++ b/spec/javascripts/diffs/components/app_spec.js
@@ -397,4 +397,61 @@ describe('diffs/components/app', () => {
       expect(wrapper.find(TreeList).exists()).toBe(true);
     });
   });
+
+  describe('hideTreeListIfJustOneFile', () => {
+    let toggleShowTreeList;
+
+    beforeEach(() => {
+      toggleShowTreeList = jasmine.createSpy('toggleShowTreeList');
+    });
+
+    afterEach(() => {
+      localStorage.removeItem('mr_tree_show');
+    });
+
+    it('calls toggleShowTreeList when only 1 file', () => {
+      createComponent({}, ({ state }) => {
+        state.diffs.diffFiles.push({ sha: '123' });
+      });
+
+      wrapper.setMethods({
+        toggleShowTreeList,
+      });
+
+      wrapper.vm.hideTreeListIfJustOneFile();
+
+      expect(toggleShowTreeList).toHaveBeenCalledWith(false);
+    });
+
+    it('does not call toggleShowTreeList when more than 1 file', () => {
+      createComponent({}, ({ state }) => {
+        state.diffs.diffFiles.push({ sha: '123' });
+        state.diffs.diffFiles.push({ sha: '124' });
+      });
+
+      wrapper.setMethods({
+        toggleShowTreeList,
+      });
+
+      wrapper.vm.hideTreeListIfJustOneFile();
+
+      expect(toggleShowTreeList).not.toHaveBeenCalled();
+    });
+
+    it('does not call toggleShowTreeList when localStorage is set', () => {
+      localStorage.setItem('mr_tree_show', 'true');
+
+      createComponent({}, ({ state }) => {
+        state.diffs.diffFiles.push({ sha: '123' });
+      });
+
+      wrapper.setMethods({
+        toggleShowTreeList,
+      });
+
+      wrapper.vm.hideTreeListIfJustOneFile();
+
+      expect(toggleShowTreeList).not.toHaveBeenCalled();
+    });
+  });
 });
diff --git a/spec/javascripts/diffs/store/actions_spec.js b/spec/javascripts/diffs/store/actions_spec.js
index 6c637097893..bca99caa920 100644
--- a/spec/javascripts/diffs/store/actions_spec.js
+++ b/spec/javascripts/diffs/store/actions_spec.js
@@ -734,6 +734,14 @@ describe('DiffsStoreActions', () => {
 
       expect(localStorage.setItem).toHaveBeenCalledWith('mr_tree_show', true);
     });
+
+    it('does not update localStorage', () => {
+      spyOn(localStorage, 'setItem');
+
+      toggleShowTreeList({ commit() {}, state: { showTreeList: true } }, false);
+
+      expect(localStorage.setItem).not.toHaveBeenCalled();
+    });
   });
 
   describe('renderFileForDiscussionId', () => {