Collapsible Left Panel - Clicking on separator should expand to 100% when no width is available in settings (#33053)

* Expand panel to full width

* Write tests

apps/web/src/viewmodels/structures/ResizerViewModel.ts

@@ -76,7 +76,7 @@ export class ResizerViewModel
     public onSeparatorClick = (): void => {
         if (this.panelHandle?.isCollapsed()) {
             const lastSize = SettingsStore.getValue("RoomList.panelSize");
-            this.panelHandle.resize(`${lastSize}%`);
+            this.panelHandle.resize(`${lastSize ?? 100}%`);
         }
     };
 

apps/web/test/viewmodels/structures/ResizerViewModel-test.ts

@@ -68,18 +68,33 @@ describe("LeftPanelResizerViewModel", () => {
         expect(() => vm.onSeparatorClick()).not.toThrow();
     });
 
-    it("should expand panel on onSeparatorClick()", () => {
+    describe("should expand panel on onSeparatorClick()", () => {
-        const vm = new ResizerViewModel();
+        it("to last non-zero width that the user set", () => {
-        SettingsStore.setValue("RoomList.panelSize", null, SettingLevel.DEVICE, 34);
+            const vm = new ResizerViewModel();
-        const mockHandle = {
+            SettingsStore.setValue("RoomList.panelSize", null, SettingLevel.DEVICE, 34);
-            resize: jest.fn(),
+            const mockHandle = {
-            isCollapsed: jest.fn().mockReturnValue(true),
+                resize: jest.fn(),
-        } as unknown as PanelImperativeHandle;
+                isCollapsed: jest.fn().mockReturnValue(true),
-        vm.setPanelHandle(mockHandle);
+            } as unknown as PanelImperativeHandle;
+            vm.setPanelHandle(mockHandle);
 
-        vm.onSeparatorClick();
+            vm.onSeparatorClick();
 
-        expect(mockHandle.resize).toHaveBeenCalledWith("34%");
+            expect(mockHandle.resize).toHaveBeenCalledWith("34%");
+        });
+
+        it("to maximum size of the panel", () => {
+            const vm = new ResizerViewModel();
+            const mockHandle = {
+                resize: jest.fn(),
+                isCollapsed: jest.fn().mockReturnValue(true),
+            } as unknown as PanelImperativeHandle;
+            vm.setPanelHandle(mockHandle);
+
+            vm.onSeparatorClick();
+
+            expect(mockHandle.resize).toHaveBeenCalledWith("100%");
+        });
     });
 
     it("should set isFocusedViaKeyboard state correctly", () => {