test(tree-view): add more test cases

tests/TreeView/TreeView.test.svelte

@@ -7,7 +7,7 @@
   let treeview: TreeView;
   let activeId: TreeNodeId = "";
   let selectedIds: TreeNodeId[] = [];
-  let expandedIds: TreeNodeId[] = [1];
+  let expandedIds: TreeNodeId[] = [];
   let nodes: ComponentProps<TreeView>["nodes"] = [
     { id: 0, text: "AI / Machine learning", icon: Analytics },
     {
@@ -81,3 +81,12 @@
 </TreeView>
 
 <Button on:click={treeview.expandAll}>Expand all</Button>
+<Button
+  on:click={() => {
+    treeview.expandNodes((node) => {
+      return /^IBM/.test(node.text);
+    });
+  }}
+>
+  Expand some nodes
+</Button>

tests/TreeView/TreeView.test.ts

@@ -17,6 +17,16 @@ describe("TreeView", () => {
     });
   };
 
+  const noExpandedItems = () => {
+    expect(screen.queryAllByRole("treeitem", { expanded: true })).toHaveLength(
+      0,
+    );
+  };
+
+  const getAllExpandedItems = () => {
+    return screen.getAllByRole("treeitem", { expanded: true });
+  };
+
   it("can select a node", async () => {
     const consoleLog = vi.spyOn(console, "log");
 
@@ -37,4 +47,30 @@ describe("TreeView", () => {
       text: "AI / Machine learning",
     });
   });
+
+  it("can expand all nodes", async () => {
+    render(TreeView);
+
+    noExpandedItems();
+
+    const expandAllButton = screen.getByText("Expand all");
+    await user.click(expandAllButton);
+
+    expect(getAllExpandedItems()).toHaveLength(5);
+  });
+
+  it("can expand some nodes", async () => {
+    render(TreeView);
+
+    noExpandedItems();
+
+    const expandSomeNodesButton = screen.getByText("Expand some nodes");
+    await user.click(expandSomeNodesButton);
+
+    expect(getAllExpandedItems()).toHaveLength(2);
+
+    expect(
+      screen.getByText("IBM Analytics Engine").parentNode?.parentNode,
+    ).toHaveAttribute("aria-expanded", "true");
+  });
 });